WO1993017556A1

WO1993017556A1 - Methods and compositions for treating plants exposed to stresses

Info

Publication number: WO1993017556A1
Application number: PCT/US1993/001942
Authority: WO
Inventors: Charles C. Shin; Nicolai A. Favstritsky
Original assignee: Great Lakes Chemical Corporation
Priority date: 1992-03-02
Filing date: 1993-03-02
Publication date: 1993-09-16

Abstract

Methods and compositions for the protection of plant tissue from damage upon exposure to chemical, air pollution, environmental and handling stresses, and to assist plant tissue in recovering from stress injuries, include the application of an effective amount of stress-protectant compositions selected from the group consisting of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl amine and mixtures thereof. The compositions are applied as aqueous solutions containing between about 0.005 and about 25 wt% of the stress-protectant components. Surfactants may be included to improved application of the compositions to the plant tissues.

Description

METHODS AND COMPOSITIONS FOR TREATING PLANTS

EXPOSED TO STRESSES

BACKGROUND OF THE INVENTION

Field of the Invention: 5 The present invention relates to methods and compositions for the treatment of plants to reduce injury due to exposure to certain stresses, and more particularly to the application of compositions to plants to minimize or prevent stress injuries. The present invention further relates to the 10 treatment of plants which have been subjected to injury due to exposure to the identified stresses. Description of the Prior Art:

Plants are subject to exposure to a variety of stresses. Chemical stresses can result from high salt concentrations 15 resulting from brackish water, or from pesticides, herbicides and the like. A great variety of chemicals, including those to which plants are not normally exposed, or those in unusually high concentrations, can have a severe impact on the growth and productivity of plants. Air pollution can 20 significantly affect the growth of plants. Environmental and handling stresses include stresses due to water deprivation, drought and excessive heat. Adverse effects may also occur during the handling of plants or plant products, such as in transplanting, rooting cuttings, germinating seeds, and 25 preserving cut flowers.

It has been known for a lonςi time that an excessive amount of chemical in the root environment reduces the growth of plants and results in low crop yield. The response to chemical concentration differs greatly among various plant 30 species. One of the worst common chemicals affecting the growth of plants and low crop yield is NaCl. Stress resulting from exposure to NaCl substantially decreases the crop yield. It has been reported that water uptake in wheat and barley was substantially decreased by increasing salinity stress. However, whether the effect is on water deficits or on high internal electrolyte concentra ion is not yet known. Of the 14 billion hectares of available land in the world, only one-fourth of it is potentially arable. Nearly 25% of this arable land is subject to salinity. Due to rapid urban development, matters are getting worse. Salt water is creeping into fresh water, and water reservoirs are becoming contaminated with chemicals and excess salt.

Techniques have been exploited in vitro to isolate salt tolerant plants and to probe the physiological mechanism of salt tolerance. A plant hormone, abscisic acid, has been reported to accelerate the growth of rice cells exposed to ionic salt, but not to water deficits elicited by non-ionic chemicals. None of the known prior art methods has been shown to be practical in alleviating stress of plants from excess ionic or nonionic salts. The purpose of this invention is to develop a chemical agent and method to alleviate injuries of plants exposed through foliage contact and root environment to stressful concentrations of chemicals. In sufficient concentrations, air pollutants injure plant foliage, significantly alter growth and yield, and thereby can change the quality of marketable plant products. For example, exposure to ozone in concentrations of 0.05 to 0.12 ppm (by volume) for 2 to 4 hours injures leaves of the most sensitive cultivars. During the summer months, the atmosphere over some areas of the United States contains levels of ozone ranging from 0.05 to 0.10 ppm (by volume). As reported by the National Loss Assessment Network, crops such as beans, soybeans, peanuts, tobacco, and cotton suffer significant yield losses at these ozone concentrations. Ozone affects vegetation throughout the United States, impairing crops, native vegetation, and the ecosystem more than any other air pollutant. In addition to ozone, major air pollutants damaging to crops include: peroxyacetyl nitrate, oxides of nitrogen, sulfur oxide, fluoride, agricultural chemicals, and ethylene and other hydrocarbons. Ozone and sulfur dioxide account for 90% of crop damage caused by air-borne pollutants. However, the additional pollutants listed, as well as others, also contribute to crop damage and losses. It has been estimated that American farmers lose $3 billion a year in damaged crops due to air pollution alone. Although there are chemicals which have been reported to reduce injury to plants due to air pollution, none yet has been of practical utility. For example, scientists reported in 1986 that the injection of ethylene diurea (EDU) into the stem of shade trees could protect the trees from ozone damage. EDU was also determined to be a growth regulator. Test results at that time indicated that EDU altered enzyme and membrane activity within the leaf cell where the photosynthesis of the plant takes place. Under the laboratory conditions, a single soil drench of the EDU was effective in providing protection against acute exposure to ozone. However, the efficacy of the compound for field application has not been established.

It is desirable to treat plants to avoid any detrimental effects that would otherwise result under these circumstances. In order to be practically useful, a chemical composition used to treat plants against these stress injuries must be non-toxic to the plants, environmentally acceptable and relatively inexpensive. The present invention satisfies these requirements and provides for the protection of plants from chemical stresses of the types previously mentioned. SUMMARY OF THE INVENTION

In accordance with this invention, there are provided methods and compositions for protecting plants and plant products from certain stresses, and for promoting recovery of plants from stress injuries. A plant anti-stress chemical composition has been discovered which comprises an aqueous solution containing an effective amount of a chemical component selected from the group of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl amine, and mixtures thereof. The solution is applied to the plant surfaces and tissues prior to and/or after exposure to the stress. The solution preferably includes between about 0.005 and about 25 wt. % of the stress protectant.

Among the objects of this invention is the provision of compositions and methods to protect plants and plant products from damage due to certain stresses, e.g., those which occur upon exposure to excessive levels of salt and other chemicals and to air pollutants such as ozone, and also which occur due to certain environmental and handling stresses, e.g., those which occur in conjunction with excessive heat, water deprivation, drought, seed germination, transplanting, rooting cuttings and preserving cut flowers.

Another object is the provision of an effective method for treating plants and plant products injured due to exposure to such stresses.

A further object of this invention is to provide such stress protectant compositions and methods which are relatively inexpensive, non-toxic and environmen ally acceptable. These and other objects and features of this invention will be apparent from the description hereafter. DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the preferred embodiment of the invention and specific language will be used to describe the same. It will nevertheless be understood that modifications and further applications of the principles of the invention are contemplated as would normally occur to one skilled in the art to which the invention relates. Exposure of plant tissue to a varjety of chemical stresses can result in serious damage. Such forms of chemical stress which can adversely affect plant tissue include stresses due to exposure to herbicides, pesticides and the like, high salt concentrations such as resulting from brackish water, and any other stress resulting from chemicals which are of a type or are at a concentration to which plants are intolerant. As used herein, the term "chemical stress" includes each of the foregoing forms of plant stress. The term "plant tissue" is used to indicate either plants or plant products subject to damage by exposure to the identified chemical stress. The present invention is not directed to the treatment of plants which have been exposed to chilling or freezing temperatures.

The extent and nature of damage resulting from exposure to the chemical stresses is exemplified by the effect of salinity on plants. Salt stress can reduce plant growth, resulting in lower weight gain of the plant, as well as reduced crop production. The impact of plant tissue treatments in regard to salt stress is an appropriate and useful model for demonstrating the efficacy of compositions and methods on the protection of plant tissue from chemical stresses addressed by the present invention.

Exposure of plants to a variety of environmental stresses can also result in serious damage. Air pollution, for example, can detrimentally affect the growth of plants. The present invention provides effective, ecologically safe a d relatively inexpensive compositions and methods for treating plants subject to exposure to air pollutants.

Injury from air pollutants has characteristic manifestations in plants and is distinguishable from other forms of injury. By way of example, the response of bean plants to ozone exposure has been well defined. When a bean plant is exposed to ozone, an injury begins as a necrotic stippling. As the injury progresses, the foliage develops a bronze appearance on most beans. The degree of injury is revealed in terms of the area of the leaves which becomes bronzed. The present invention is focused on dealing with such air pollution stresses, and is not directed to other forms of plant stress such as that resulting from exposure to chilling or freezing temperatures.

Among the environmental stresses, exposure to air pollutants is of particular concern. As used herein, the term "air pollutants" refers to chemical agents at concentrations in the air which cause or potentially cause damage to plants and/or plant tissues. The term "polluted air" refers to air containing detrimental levels of pollutants. Air pollutants which may adversely affect plants include those discussed in the prior art, such as peroxyacetyl nitrate, oxides of nitrogen, sulfur oxide, fluorides, agricultural chemicals, ethylene and other hydrocarbons, and ozone. The present invention provides compositions and methods which reduce injuries due to air pollutants and/or assist plants in recovering from such injuries. The extent and nature of damage resulting from exposure to polluted air is exemplified by the effects of ozone on plants. At detrimental levels of ozone in the air, injury to plants leads to leaf chlorosis or necrosis, decreased photosynthetic activity, altered metabolite pools, change in enzyme activity and effects on membrane permeability. Ozone and oxidative stress often lead to damage of membrane lipids, at least partly via lipid peroxidation. Ozone stress is an appropriate and useful model for demonstrating the efficacy of compositions and methods on the protection of plants from air pollution. The present invention provides compositions and methods which can reduce injuries of plants due to polluted air, especially due to ozone.

Exposure of plant tissue to a variety of environmental and handling stresses can also result in serious damage. Many of these stresses are related to the amount of water available to the plant tissue, and the present invention is concerned in particular with stresses relating to this phenomenon. Such forms of environmental stress which can adversely affect plant tissue include stresses due to water deprivation (e.g., absence of rainfall, lack of irrigation, low humidity, etc.), drought and excessive heat. As used herein, the term "environmental stress" includes each of the foregoing forms of plant stress. Adverse effects may also occur through a similar mechanism during the handling of plants or plant products, such as in transplanting plants, rooting cuttings, germinating seeds, and preserving cut flowers. Plants a d plant products are also subjected to related stress following harvesting and during subsequent transportation. As used herein, the term "handling stress" encompasses each of the foregoing forms of stress. The term "plant tissue" is used to indicate either plants or plant products subject to damage by exposure to the identified environmental or handling stresses. The present invention is not directed to the treatment of plants which have been exposed to chilling or freezing temperatures. The extent and nature of damage resulting from exposure to the environmental and handling stresses is exemplified by the effect of water deprivation on plants. Water deprivation can reduce plant growth, resulting in lower weight gain of the plant, as well as reduced crop production. The damage is also exemplified by the effect on seed germination, with untreated seeds showing delayed and lower percentage germination. The impact of plant tissue treatments in regard to water deprivation and seed germination are appropriate and useful models for demonstrating the efficacy of compositions and methods on the protection of plant tissue from the water-related, environmental and handling stresses addressed by the present invention.

In accordance with this invention, a plant tissue, stress-protectant composition has been discovered which comprises an aqueous solution containing a stress-protectant component selected from the group consisting of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl amine, and mixtures thereof. Preferably, the composition comprises an aqueous solution comprising between about 0.005 and about 25 wt. percent of the stress-protectant component, and most preferably comprises between about 0.05 and about 5 wt. percent of the stress-protectant component. It has also been discovered that the stress-protectant composition is effective in promoting a recovery of plant tissue from the indicated stresses. Tetrahydrofurfuryl alcohol is a colorless, high boiling, primary alcohol having the following structure:

Tetrahydrofurfuryl amine is a colorless, high boiling, primary amine having the following structure:

Both tetrahydrofurfuryl alcohol and tetrahydrofurfuryl amine exhibit stress-protectant properties as against exposure to the described stresses. However, Letrahydrofurfuryl alcohol is preferred in accordance with the present invention.

Tetrahydrofurfuryl alcohol (THFA) is produced by the hydrogenation of furfuryl alcohol. As expected on the basis of its structure, tetrahydrofurfuryl alcohol exhibits behavioral characteristics of both alcohol and ethers. Due to its cyclic ether structure, tetrahydrofurfuryl alcohol possesses distinctly unique solvent properties which are desirable. THFA is low in volatility (vapor pressure is 2.3 mm Hg at 39°C), non-damaging and non-toxic, biodegradable, easily absorbable, able to penetrate membranes, considerably soluble in water, in addition to forming multiple hydrogen bonds, and able to dissolve electrolytes. Tetrahydrofurfuryl amine has similarly useful characteristics.

The resistance of plant tissues to the described chemical, air pollution, environmental and handling stresses is increased through the application of the stress-protectant compositions of this invention, such as by spraying or root drenching methods. The composition is applied at moderate, ambient temperatures, i.e., at temperatures of the air surrounding the plant tissues above a chilling temperature. Any conventional apparatus suitable for aqueous solutions may be employed for the foregoing application methods. For spraying, the plant tissues to be treated are thoroughly sprayed so that all of the plant tissue surfaces are substantially covered. Due to the size, shape and/or other characteristics (such as surface properties) of a plant, an application may require two or more sprayings. The compositions may be formulated and supplied to the user ready to apply, or in concentrated form and diluted to the desired strength prior to application to the plant tissues. No special handling or mixing steps are required. THFA and tetrahydrofurfuryl amine are stable in aqueous solution. Moreover, these compositions are stable to light and do not need to be stored in an opaque container nor prepared immediately prior to application.

Since aqueous THFA or tetrahydrofurfuryl am ne solutions, or mixtures thereof, may not completely wet the surfaces of some plant tissues, such as leaves having waxy surfaces, it is preferred for some applications that the compositions include non-ionic surfactants. Suitable surfactants operate as penetrating agents and otherwise may be inert, or at least non-interfering, components. For example, two different surfactants, polyoxyethylene sorbitan monolaurate (Tween 20) and polyoxyethylene sorbitan monooleate (Tween 80) have been found to improve the effectiveness of the compositions in appropriate circumstances. When non-ionic surfactants are used, it is preferred that the stress-protectant composition contain between about 0.005 and about 0.5 wt. percent of the non-ionic surfactant.

The stress-protectant compositions of the present invention may be applied to the plant tissues from immediately prior to 24 hours prior to exposure to the stress conditions, and preferably at least about 4 or more preferably at least about 12 hours prior to exposure. For optimal results it is preferred that the stress-protectant compositions be repeatedly applied prior to exposure to the stress. For example, it is preferred that the compositions be applied periodically about every week during the season when the stress level of air pollutants is high. For additional protection, the stress-protectant compositions may be applied immediately after the stress exposure to help the plant tissues recover from any stress injuries that are incurred. For maximum protection during extended periods of exposure to stress conditions, it may be desirable to apply the stress-protectant compositions periodically, such as weekly.

The following examples serve to further illustrate the invention, with all percentages being by weight unless otherwise indicated. It will be appreciated that these examples are demonstrative only, and the applicability of the compositions and methods described therein extends to the various other plants, as well as the differing types of chemical stresses, elsewhere described herein.

The efficacy of the present invention is readily demonstrated by the results of experiments showing reduction in plant injuries induced by salt stress. The salt solution chosen for this study was an aqueous solution of NaCl and MgCl„, which are two major components of sea water. The concentrations of NaCl and MgCl in average sea water are 0.43 mole/Kg for NaCl and 0.054 mole/Kg for MgCl . Total ionic salt concentration in sea water is 3.5%. An aqueous solution was prepared using reagent grade NaCl and MgCl_? in the approximate concentrations of average sea water, and with a total salt concentration of 3.75%.

Fifty-four uniform pepper plants (c.v. Ma Belle) in 9 oz . plastic cups were selected for the experiment. One-half of the plants (27 plants) was treated with an aqueous mixture solution of 0.25% THFA and 0.1% Tween 20, and the remaining 27 plants were treated with an aqueous solution 0.1% Tween 20. The treatment was made by foliage spraying until it started to drip.'

Twenty-four hours after the treatment, the plants underwent salt stress. AIL 54 plants were given 15 ml of the 3.75% aqueous solution of NaCl and MgCl„. The treatment and stress procedure was repeated every seven days for four weeks, after which normal greenhouse care and watering were resumed. Survival rate was determined after 14 days. Fourteen plants out of the 27 plants treated with the aqueous solution of 0.25% THFA and 0.1% Tween 20 survived, whereas only three plants out of the 27 non-treated plants survived.

All surviving plants were transplanted from the 9 oz. plastic cups to 8" plastic pots. The plants were moved from an indoor greenhouse to an outdoor vinyl top greenliouse for harvest. After the transplanting, all three of the non-treated plants a d six of lie treated plants died, leaving eight treated plants for observation.

E ample__2

5 The foregoing procedures of Example 1 are repeated for other stress-protectant compositions of the present invention. For example, the anti-stress agents include:

1. tetrahydro rfuryl alcohol dissolved in deionized (DI) water to make 0.05% and 0.5% THFA aqueous

10 solutions;

2. 0.1 parts of a surfactant, polyoxyethylene sort)itan monolaurate (Tween 20), and 0.05 - 0.5 parts tetratiydrofurfuryl alcohol dissolved in 99.40 - 99.85 parts DI water to make an aqueous 0.05 - 0.5%

15 THFA + 0.1% Tween 20 solution;

3. tetrahydrofurfuryl amine dissolved in DI water to make 0.3% tetrahydrofurfuryl amine aqueous solution;

4. 0.10 parts of a surfactant, Tween 20, and 0.3 parts of tetrahydrofurfuryl amine dissolved in 99.60 parts

20 of DI water to make an aqueous 0.3% tetrahydrofurfuryl amine + 0.10% Tween 20 solution; and

5. the foregoing solutions 2 and 4, except using Tween 80.

'25 Application of the foregoing compositions to the plant tissues, prior to exposure to the salt stresses, provides protection against stress injuries. The treated plants display better growth than the untreated plants.

Protection of the plants is also obtained upon treatment

30 with aqueous solutions containing as low as 0.005 wt.% and as high as 25 wt.% of the tetrahydrofurfuryl amine, as well as mixtures of the alcohol and the amine yielding total weight percentages as indicated. Generally, treatments with the amine and mixtures of the amine and the alcohol give comparable results to treatments with the tetrahydrofur uryl alcohol solutions alone. Treatment w th Tween 20 or Tween 80 alone has no effect on protecting plants from chemical stress injuries.

Example 3

Repetition of the foregoing procedures for other chemical stresses, including stress due to exposure to excessive concentrations of herbicides, pesticides and other ionic and non-ionic cliemicals demonstrates that protection of the plants is also obtained upon treatment with the various protectant compositions of Examples 1 and 2.

Example 4

The efficacy of the present invention is also read ly demonstrated by tLie results of experiments showing reduction in ozone-induced plant injuries. For this purpose, an ozone sensitive bean plant, c.v. Oregon 91, was used to test the effectiveness of the antipollution agents. For the first study, the pollution stress protectant comprised solutions of differing weight percentages of tetrahydrofurfuryl alcohol in water.

Bean seeds were planted in 6" diameter plastic pots containing a mixture of peat, perlite and vermiculite. The plants were germinated and grown in a clean air greenhouse. The incoming air in the greenhouse was filtered with activated charcoal to make sure that the plants would grow in an environment absolutely free of ozone contamination. When the tliird trifoliate leaves were developed on the bean plants (25 days old), 20 uniform plants, divided into sets of four, were selected for the test. Each set of four plants was treated by spraying with various concentrations of THFA solution. The control plants were treated with deionized water. Twenty-four hours after the treatment, the plants were moved to an ozone fumigation chamber. The plants were fumigated with 0.15 ppm ozone for 5.3 hours.

Two days after the ozone fumigation, the exposed plants were assessed visually for injury to two primary and two trifoliate leaves. The visible injury was estimated in terms of area on a 0 to 100% scale, in 5% increments. .The injury percents in Table 1 show that the chemical treatment significantly reduced the injury to the plants.

TABLE 1

Concentration^) Primary Primary Trifoliate Trifoliate Average

Leaf #1 Leaf #2 Leaf #1 Leaf #2 Injury %

Example 5

The same experimental procedure detailed in Example 4 was followed in this test. Twenty-one uniform plants (26 days old) , divided into seven sets of three, were selected for the test. Each of the three plants in a set was treated with a given concentration of the stress protectant.

Twenty-four tiours after the treatment, the plants were moved to an ozone fumigation chamber. The plants were fumigated with 0.15 ppm ozone for 5 hours. Four days after the ozone fumigation, the injury to each of the exposed plants was assessed visually. The average injury percentages in Table 2 stiow that treated plants had a substantially lower injury rate than the untreated plants. The effectiveness improved as the concentration of the anti-pollution agent was increased.

TABLE 2

Concentration ^) Primary Primary Trifol i ate Trifoliate Average

Leaf #1 Leaf #2 Leaf #1 Leaf #2 Injury %

0.00 0.05 0.20 0.50 1.00 2.00 4.00

Example G

In this test, all the plants tested were fumigated twice. After the results in Example 5 were tabulated, the same 21 bean plants used in Example 5 were fumigated a second time at the rate of 0.15 ppm ozone for 6 hours. Three days after the second fumigation, the plants were evaluated and data was taken. The treated plants had a much lower injury percent than the non-treated plants. The results in Table 3 show that effectiveness generally increased as the concentration of the antipollution agent was increased. TABLE 3

Concentration ( .) Primary Primary Trifoliate Trifoliate Average

Leaf #1 Leaf #2 Leaf #1 Leaf #2 Injury %

The same experimental procedure detailed in Example 4 was followed in tliis test . Eighteen uniform plants were selected and treated. Plants were fumigated at a rate of 0.15 ppm ozone for 6 hours . After 5 days , the plants were assessed to determine the injury to exposed plants and the results are listed in Table 4 , sliowing good efficacy of the treatments . For example, the average injury percentage of tlie treated plants at 2% of tlie anti-pollution agent treatment was 10% , compared with 26% for the untreated control plants . TABLE 4

Concentration^) Primnry Primary Trifoliate Trifoliate Average

Leaf #1 Leaf #2 Leaf #1 Leaf #2 Injury %

0.00 0.05 0.20 0.50 1.00 2.00

Example 8

The foregoing procedures Examples 4-7 are repeated for other stress-protectant compositions of the present invention set forth in Example 2. Application of the foregoing compositions to the plants prior to exposure to polluted air, e.g. ozone-containing air, provides protection against air pollution injuries. The treated plants display better growth than the untreated plants. Protection of the plants is also obtained upon treatment with aqueous solutions containing as low as 0.005 wt.% and as high as 25 wt.% of the tetrahydrofurfuryl amine, as well as mixtures of the alcohol and the amine yielding total weight percentages as indicated. Generally, treatments with the amine and mixtures of the amine and the alcohol give comparable results to treatments with the tetrahydrofurfuryl alcohol solutions alone. Treatment with Tween-20 alone has no effect on protecting plants from air pollution injury. Example 9

The efficacy of the present invention is also readily demonstrated by the results of experiments showing reduction in plant injuries induced by water deprivation. A set of twenty-four pepper plants (c.v. MaBelle) with similar growth development (39 days old) was selected. The average height of tlie plant was 7.5 cm. In order to achieve uniform water status, each plant was watered with a fixed amount of DI water, 15 ml, for 16 days. At 55 days old, these peppers were ttien divided into four sets (6 plants per set). For each treatment, the first set received 15 ml of water, the second set received 5 l of DI water, the third set received 5 ml of an aqueous mixture solution of 0.2% THFA and 0.1% Tween 20, and the fourth set received 5 ml of an aqueous solution of 0.5% THFA and 0.1% Tween 20. The treatment was repeated three times a week for 2 weeks and then normal watering was resumed as usual until harvest time. The harvest data of the tests are listed in Table 5, with the last column showing as a percent the number of plants which were lost as a result of the water deprivation stress. The results show that plants treated with an aqueous mixture solution of THFA and Tween 20 performed substantially better than the untreated plants.

Table 5 - Harvest Results per 6 Water Stressed Pepper Plants

Stress

Non-Stress DL Water 13 34.1 g _ .3 g 170% 0 Co trol

67% water DI Water 7 23.4 g J64 g - 63 w/held 2 wks

67% water 0.2% THFA & 9 27.8 g 250 g 52% 44 w/held 2 wks 0.1% Tween 20

67% water 0.5% THFA & 1. 34.2 g 479 g 192% 0 w/held 2 wks 0.1% Tween 20

Example 10

The experimental procedure for Example 9 was repeated. Fifteen bean plants each were treated in various ways and the stress-protectant agent was applied in two different application methods (spray and root drench). The results listed in Table 6 show that both spray and root drench applications are effective in alleviating injury of the bean plants from water deficiency. The bean plants treated with an aqueous solution of 0.5% THFA and 0.1% Tween 20 harvested as much as the non-treated, non-stressed bean plants. The ef ectiveness of root drench application indicates that if THFA is absorbed efficiently, THFA without surfactant Tween 20 is also effective in alleviating the injury of plants. Table 6 - Harvest Results per 15 Water Stressed Bean Plants

Example 11

The experimental procedure in Example 9 was followed. Each set of 5 cucumber plants was treated with aqueous solutions of DI water, 1.0% THFA plus 0.1% Tween 20 for spraying, 1.0% THFA only for root drenching. The harvest results in Table 7 show both root drenching and leaf spraying of ttie agent saved approximately 30% of the crop otherwise lost to water deficiency. Table 7 - Harvest Results per 5 Water Stressed Cucumber Plants

Stress Treatment Total Wt. of % Increase % Lost in Yiel

Harvest, g Over Control Due to Stress

67% water DI water 2399 - 29 w/held for 2 wks Root Drench

67% water 1.0% THFA 3057 24.7 8 w/held for 2 wks Root Drench

67% water 0.1% THFA 2875 19.8 14 w/held for 2 wks Root Drench 67% water DI Water 1939 - .2 w/held for 2 wks Foliage Spray

67% water 1.0% THFA & 2475 27.6 26 w/lield for 2 wks 0.1% Tween 20

Foliage Spray 67% water 0.1% THFA δ. 2974 53.4 11 w/held for 2 wks 0.1% Tween 20

Foliage Spray

Non-Stress DI water 3338 - 0 Control

Example 12

A total of ninety-two bean plants with similar physical characteristics was transplanted into forty-six 8" plastic pots (two plants per pot) . When the bean plants were 14 days old water conditioning began. It took 4 weeks to get a uniform water status before water deficiency became stressful. The first set of 23 pots was treated with an aqueous solution of THFA containing 0.25% of THFA and 0.1% Tween 20 surfactant. The second set of pots was treated with an aqueous solution of 0.1% Tween 20. The treated plants underwent water restriction for 40 days before regular greenhouse watering resumed. During this stress period the plants were treated once every seven days for five consecutive weeks. After 14 days of regular watering, the harvest results were collected as shown in Table 8. The bean plants treated with an aqueous mixture solution of 0.25% THFA and 0.1% Tween 20 produced 31% more fruit than the plauts treated with an aqueous solution of 0.1% Tween 20. The average weight of pods for the treated plants was 21% greater than for the untreated plants.

Table 8 - Harvest Results per 4G Water Stressed Bean Plants

Total Yield, g Avg.Wt. of Pod

511.7 4.0 669.6 3.3

30.9- 21.2^

Example 13

The test procedure in Example 12 was repeated. In this example, ttie stress period was shortened (21 days vs. 40 days stress). The harvest results are listed in Table 9. The test results indicate that if the bean plant receives more stress, the effectiveness of the treatment is greater. Table 9 - Harvest Results per 50 Water Stressed Bean Plants

Treatment Total # Total Yield, g Av . W of Pods of Pod

0.25% THFA & 99 361.5 g 3.65 0.1% Tween 20

Control (0.1% 90 326.3 g 3.62 Tween 20)

% Increase Over 10.0% 10.8- 0.85 Control

Example 14

The efficacy of the present invention is also demonstrated by the results of experiments showing reduction in plant injuries induced at the time of seed germination. An annual loss of as much as $60 MM (in 1980 dollars) in the cotton industry reflects the economic impact of injuries incurred immediately following field planting. Other crops that suffer stand loss, delayed maturity, and reduced yield as a result of injuries following planting include soybean, lima bean, cucumbers, tomato, pepper, eggplant, okra, and various cereal crops. Experimental evidence leads to tlie conclusion that the seeds are particularly sensitive during initial hydration. The level of seed moisture determines sensitivity of the seed to injury during inbibition. The cotton variety (Stoneville) was planted on

February 19, 1992 in 9 oz. plastic cups for germination evaluation. Prior to planting, twenty seeds each were imbibed in a 1% aqueous solution of THFA and DI water respectively, at -1°C for six hours. The seeds were germinated in an indoor greenhouse, under artificial fluorescent light, at 30°C with the lights on. The light period was 14 hours on and 10 hours off. On February 24, 1992, the emerged embryo were counted. The germination rate of the seed treated with THFA was 85% (17 emerged out of 20 seeds), compared with 35% (7 emerged out of 20 seeds) of DI water treated seed. The seed treated with aqueous THFA solution germinated earlier than ttie non-treated seed.

Example 15

The sweet corn varieties (Sweetheart, Classic, and Champ) were planted on May 8, 1991 in four 40' rows. Prior to planting, half of each seed lot from Classic and Champ was imbibed with water and with the agent (0.8% THFA and 0.2% Tween 20) for 62 hours at 34°F. The niglit temperatures for 4 days preceding the planting date for corn were cold enough (minimum temperature 0.5°C to 9.5°C) to stress germination and emergence. Actual soil temperature on the May 8 planting date was about 10°C in the top 10 cm of soil. The sweet corn was Liarvested on July 30, 1991. The combined harvest of both sweet corn varieties treated with tLie chemical agent was 41% liigher in ear number (116 vs. 82), and 56% greater in ear weigtit (64.5 vs. 41.8 lbs.) compared with the water treated check. The ears were also larger in the treated corn varieties than the non-treated checks.

Example 16

The foregoing procedures of Examples 9-15 are repeated for other stress-protectant compositions of the present invention set forth in Example 2. Application of the foregoing compositions to the plant tissues, prior to exposure to the environmental and handling stresses, provides protection against stress injuries. The treated plants display better growth than the untreated plants. Protection of the plants is also obtained upon treatment with aqueous solutions containing as low as 0.005 wt.% and as high as 25 wt.% of the tetrahydrofurfuryl amine, as well as mixtures of the alcohol and the arnine yielding total weight percentages as indicated. Generally, treatments with the amine and mixtures of the amine and the alcohol give comparable results to treatments with the tetrahydrofurfuryl alcohol solutions alone. Treatment with Tween 20 alone has no effect on protecting plants from environmental or handling stress injuries.

Exaπιple__17

Treatment with the inventive compositions of plants which have already received stress injuries also contributes to plant recovery and improved plant growth. Plants, injured from the various chemical stresses as set forth in Example 3, which are treated immediately following exposure to the injurious stresses, display better growth and development than untreated plants. Plants, injured from air pollution exposure, which are treated immediately following exposure to the injurious stresses, display better growth and development than untreated plants. Plants, injured from environmental and handling stress exposure, which are treated immediately following exposure to the injurious stresses, display better growth and development than untreated plants.

While the invention has been described in detail in the foregoing description and its specific Examples, the same is to be considered as illustrative and not restrictive in character. Only the preferred embodiments have been described, and all changes and modifications that come within the spirit of the invention are desired to be protected.

Claims

What is claimed is:

1. A method for reducing damage to plant tissue upon exposure to chemical, air pollution, environmental and handling stresses which comprises applying to the plant tissue an effective amount of a stress-protectant composition selected from the group consisting of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl amine and mixtures thereof.

2. The method of claim 1 in which said applying comprises applying an aqueous solution of the stress-protectant composition.

3. The method of claim 2 in which the aqueous solution contains between 0.005 and 25 wt% of the stress-protectant composition.

4. The method of claim 3 in which the aqueous solution contains between 0.05 and 5.0 wt% of the stress-protectant composition.

5. The metliod of claim 2 in which the stress-protectant composition consists essentially of an aqueous solution of tetrahydrofurfuryl alcohol.

6. The metliod of claim 5 in which tlie aqueous solution contains between 0.05 and 5.0 wt% of the tetrahydrofurfuryl alcohol .

7. The method of claim 2 in which the aqueous solution further contains a non-ionic surfactant.

8. The metliod of claim 7 in which the aqueous solution contains between 0.05 and 0.5 wt% of the non-ionic surfactant,

9. The method of claim 7 in which the non-ionic surfactant is selected from tlie group consisting of polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan rnonooleate.

10. The method of claim 1 in which said stress-protectant composition is applied a sufficient time prior to exposure to the stress to permit at least partial absorption of the composition by the plant tissue.

11. The method of claim 10 in which the stress-protectant composition is applied at least about 4 hours prior to exposure of the plant tissue to the stress.

12. The method of claim 10 in which the stress-protectant composition is applied at least about 12 hours prior to exposure of the plant tissue to the stress.

13. The method of claim 10 in whicLi the stress-protectant composition is applied to the plant tissue at least twice prior to exposure of the plant tissue to the stress.

14. The method of claim 10 in which the stress-protectant composition is also applied to the plant tissue after exposure of the plant tissue to the stress.

15. The metliod of claim 1 for reducing damage to plant tissue upon exposure to salt stress.

16. The method of claim 1 for reducing damage to plant tissue upon exposure to polluted air containing ozone as at least one of the air pollutants.

17. The method of claim 1 for reducing damage to plant tissue upon exposure to water deprivation stress.

18. The method of claim 1 for reducing damage to plant tissue upon seed germination.

19. A method for increasing the resistance of plant tissue to damage upon exposure to chemical, air pollution, environmental and handling stresses which comprises applying to the plant tissue an effective amount of a stress-protectant composition selected from the group consisting of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl amine and mixtures thereof.

20. The metliod of claim 19 in which said applying comprises applying an aqueous solution of the stress-protectant composition, the solution containing between 0.005 and 25 wt% of the stress-protectant composition.

21. Tlie method of claim 20 in which the stress-protectant composition is applied at least about 4 hours prior to exposure of the plant tissue to the stress.

22. The method of claim 21 in which the aqueous solution contains between 0.05 and 5.0 wt% of the stress-protectant composition.

23. The method of claim 22 in which the stress-protectant composition consists essentially of an aqueous solution of tetrahydrofurfuryl alcohol.

24. The method of claim 22 in which the aqueous solution further contains between 0.05 and 0.5 wt% of a non-ionic surfactant selected from the group consisting of polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan rnonooleate.

25. A method for the treatment of plant tissue injured due to exposure to chemj al, air pollution, environmental and handling stresses which .,;omprises applying to the plant tissue an effective amount of a stress-recovery composition selected from the gioup consisting of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl amine and mixtures thereof.

26. The method of claim 25 in which said applying comprises applying an aqueous solution of the stress-recovery composition.

27. The method of claim 26 in which the aqueous solution contains between 0.005 and 25 wt% of the stress-recovery composition.

28. The method of claim 27 in which the aqueous solution contains between 0.05 and 5.0 wt% of tlie stress-recovery composition.

29. The method of claim 28 in which the stress-recovery composition consists essentially of an aqueous solution of tetrahydrofurfuryl alcohol.

30. The method of claim 29 in which the aqueous solution contains between 0.05 and 5.0 wt% of the tetrahydrofurfuryl alcohol.

31. The method of claim 26 in which the aqueous solution further contains a non-ionic surfactant.

32. The method of claim 31 in which the aqueous solution contains between 0.05 and 0.5 wt% of the non-ionic surfactant. 33. The method of claim 31 in which the non-ionic surfactant is selected from the group consisting of polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate.

5 34. An aqueous plant tissue chemical, air pollution, environmental and handling stress protectant solution comprising between about 0.05 and 0.5 wt % of a non-ionic surfactant selected from the group consisting of polyoxyethylene sorbitan monolaurate and polyoxyethylene 0 sorbitan monooleate and between about 0.005 and 25 wt % of a stress protectant component selected from the group consisting of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl amine and mixtures thereof.

35. An aqueous plant tissue chemical, air pollution, 5 environmental and handling stress protectant solution comprising between about 0.05 and 0.5 wt % of a non-ionic surfactant selected from the group consisting of polyoxyetliylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate and between about 0.005 and 25 wt % of a o stress protectant component tetrahydrofurfuryl alcohol.

36. An aqueous plant tissue chemical, air pollution, environmental and handling stress protectant solution consisting of polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate and between about 0.005 5 and 25 wt % of a stress protectant component selected from the group consisting of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl amine and mixtures thereof. AMENDED CLAIMS

[received by the International Bureau on 12 July 1993 (12.07.93); original claims 15-24 cancelled; original claims 1-5, 10-14, 25-29 and 34-36 amended; other claims unchanged (5 pages)]

1. A method for increasing the resistance of plant tissue to damage upon exposure to NaCl, MgCl, ozone, and water deprivation thereby reducing damage to plant tissue

5 upon exposure to NaCl, MgCl, ozone, and water deprivation which comprises applying to the plant tissue an effective amount of a NaCl, MgCl, ozone, and water deprivation stress-protectant composition selected from the group consisting of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl 0 amine and mixtures thereof.

2. The method of claim 1 in which said applying comprises applying an aqueous solution of the NaCl, MgCl, ozone, and water deprivation stress-protectant ^omposj. XoτrX^

3. The method of claim 2 in which the aqueous

!5 solution contains between 0.005 and 25 wt% of the NaCl, MgCl, ozone, and water deprivation stress-protectant composition.

4. The method of claim 3 in which the aqueous solution contains between 0.05 and 5.0 wt% of the NaCl, MgCl, ozone, and water deprivation stress-protectant composition.

0 5. The method of claim 2 in which the NaCl, MgCl, ozone, and water deprivation stress-protectant composition consists essentially of an aqueous solution of tetrahydrofurfuryl alcohol. 6. The method of claim 5 in which the aqueous solution contains between 0.05 and 5.0 wt% of the tetrahydrofurfuryl alcohol.

7. The method of claim 2 in which the aqueous 5 solution further contains a non-ionic surfactant.

8. The method of claim 7 in which the aqueous solution contains between 0.05 and 0.5 wt% of the non-ionic surfactant.

9. The method of claim 7 in which the non-ionic 10 surfactant is selected from the group consisting of

^^~ _=_-g lyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate.

10. The method of claim 1 in which said NaCl, MgCl, ozone, and water deprivation stress-protectant composition is

15 applied a sufficient time prior to exposure to the stress to permit at least partial absorption of the composition by the plant tissue.

11. The method of claim 10 in which the NaCl, MgCl, ozone, and water deprivation stress-protectant composition is

20 applied at least about 4 hours prior to exposure of the plant tissue to the stress. 12. The method of claim 10 in which the NaCl, MgCl, ozone, and water deprivation stress-protectant composition is applied at least about 12 hours prior to exposure of the plant tissue to the stress.

13. The method of claim 10 in which the NaCl, MgCl, ozone, and water deprivation stress-protectant composition is applied to the plant tissue at least twice prior to exposure of the plant tissue to the stress.

14. The method of claim 10 in which the NaCl, MgCl, ozone, and water deprivation stress-protectant composition is also applied to the plant tissue after exposure of the plant tissue to the stress.

25. A method for the treatment of plant tissue injured due to exposure to NaCl, MgCl, ozone, and water deprivation which comprises applying to the plant tissue an effective amount of a stress-recovery composition selected from the group consisting of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl amine and mixtures thereof.

26. The method of claim 25 in which said applying comprises applying an aqueous solution of the NaCl, MgCl, ozone, and water deprivation stress-recovery composition.

27. The method of claim 26 in which the aqueous solution contains between 0.005 and 25 wt% of the NaCl, MgCl, ozone, and water deprivation stress-recovery composition. 28. The method of claim 27 in which the aqueous solution contains between 0.05 and 5.0 wt% of the NaCl, MgCl, ozone, and water deprivation stress-recovery composition.

29. The method of claim 28 in which the NaCl, MgCl, ozone, and water deprivation stress-recovery composition consists essentially of an aqueous solution of tetrahydrofurfuryl alcohol.

32. The method of claim 31 in which the aqueous solution contains between 0.05 and 0.5 wt% of the non-ionic surfactant.

33. The method of claim 31 in which the non-ionic surfactant is selected from the group consisting of polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate.

34. An aqueous plant tissue NaCl, MgCl, ozone, and water deprivation stress protectant solution comprising between about 0.05 and 0.5 wt % of a non-ionic surfactant selected from the group consisting of polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate and between about 0.005 and 25 wt % of a NaCl, MgCl, ozone, and water deprivation stress protectant component selected from the group consisting of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl amine and mixtures thereof.

35. An aqueous plant tissue NaCl, MgCl, ozone, and water deprivation stress protectant solution comprising between about 0.05 and 0.5 wt % of a non-ionic surfactant selected from the group consisting of polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate and between about 0.005 and 25 wt % of a NaCl, MgCl, ozone, and water deprivation stress protectant component tetrahydrofurfuryl alcohol.

36. An aqueous plant tissue NaCl, MgCl, ozone, and water deprivation stress protectant solution consisting of polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate and between about 0.005 and 25 wt % of a NaCl, MgCl, ozone, and water deprivation stress protectant component selected from the group consisting of tetrahydrofurfuryl alcohol, tetrahydrofurfuryl amine and mixtures thereof.