CA1243237A - Application of specific lighting treatments for promotion of anthocyanin in economically important crops - Google Patents

Abstract

APPLICATION OF SPECIFIC LIGHTING TREATMENTS FOR PROMOTION
OF ANTHOCYANIN IN ECONOMICALLY IMPORTANT CROPS

Abstract of the Disclosure Anthocyanin formation in fruit and crop including apples, grapes, cranberries, and poinsettia can be improved by a night-break treatment, prior to harvest, of both blue and red lights having a maximum emission peaks centered around 448 nm and 660 nm, respectively.
Following harvest, apples in cold storage can be subjected to continuous red light.

Description

3~37 APPLïCA~rl~N OF spE~:rE~c IIGilTIMG TREATr~ENTS FOR PRO~OTION
_ ANTHOCY~NIM I~ ECOMOMTC~LLY IMPORT~NT CROPS

This invention relates to the use of specific lighting treatments for improving anthocyanin formation in economically important fruit and ornamental crops, without affecting other produce quality features, and crop growth and development. Accordingly, it is a general object oF
this invention to provide new and improved methods of such character.
rrhe anthocyanins are water-soluble pigments which are responsible for the attract:ive colors of flowers, leaves and fruits. Apart from their biological role, they are important aesthetically and economically, since their formation and stability are of significance in the marketability of p3ant products.
In the past, red color improvement of agricultural produce in fields and greenhouses has been accomplished by spraying or treating the crops and~or speci-fic crop parts with chemical regul~tors. In some instances, geretic selection and breeding methods have been used for color improvement.
Chemical regulators that have been used by growers for timely development of red color in certain ornamental and fruit crops teilded to produce undesirable side effec-ts (de~oliation, reduction in storac~e-life~ root inhibi~ion, etc.~ and often e~hibited a pronounced variability in responses. Cenetic selection and breeding approaches are abor intensive and time-consuming.
It is kno-.Jn that anthocyanin s~nthesis in a wide range of tissues ant1 plant species is promoted by ligh~.
The light promotion appears -to be mediated by at least iwo photochemical reactions: 1~ a low energy, red/far-red reversible, phytochrome-controlled reaction; and 2~ a hitfh irradiante reac~ion (HIR~, mos~ effective at the blue and far-red region oE the visible light spectrum. rrhe HIR of tr~

~ 3~7 anthocyanin accum~llation, in -the past, has been u~ually investigated and interpretec1 either in terms o~
phytoehrome or of another, yet unknown, photoreeeptor.

The timely development of red color in certain ornamental and fruit erops has importan~ economic bearing in the produetion and marke-~ing of agricultural produce.
There are manv faetors which affeet anthoeyanin formation, one of whieh is the influence of light. The influenee of light on fruit and ornamental erops was investigated using various approaehes. They are as follows: Whole green mature apples and/or cranberries held in regular cold storage were exposed to a combined treatment of blue (0.82mW/cm2~ and red {0.30mW/em2) lights with maximum emission peaks eentered around 448nm and 6~0nm, respectively, at different time intervals. The results showed a signi ieant improvement in anthoeyanin formation (46% more on the average relative to either blue or red light treatm~nt alone). Similarly, anthoeyanin formation in s~;ins of mature apples by post-harvest irradiation with red and blue lights at 10C was substantially improved (35% more on the average relative to unlighted eontrol groups).
Aeeordingly, the present invention provides a method of improving anthocyanin formation in a product seleetecl from the group eonsisting of fruit and crop eomprising expos~ng said prod~et to a eombined treatment o~ blue and red lights.
The cro2s ean be exposed up to 40 days prior to harvest by high intensity discharge and/or VHO narrowband fluoreseent lamps, having an intensity range of 1 to .. ...

-' ~2~2~
~3-3-015 C~l --3~

200 ~/cm2 for a period oE one to four hours per day.
Apples prior to harves-t, preferabl~, are exposed to both blue and red lights, while poinsettia should he exposed to red light only. Following harvestl apples in cold st.orage can be continuously exposed to red or red and blue lights for a period of four days.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. l is an action spectrum for anthocyanin formation in selected model crops in which disks were - incubated in 0.1 molar sucrose and in light of various wavelengths;
FIG. 2 is a chart illustrating the effect of light intensity on anthocyanin formation in cranberry (C) and apple fruit (A) disks;
FIG. 3 is a chart illustrating the effect of light intensity on anthocyanin forma~ion in poinsetti.a leaf disks;
FIG. 4 is a time course for anthocyanin synthesis in poinsettia leaf disks; and FIG. 5 is a time course of anthocyanin synthesls in apple fruit disks.

E~periments, both in the field with various crops, and studies using in vitro systems, have shown that red color development can be enhanced through effective light exposure.

.. , _ .... . .. . ., .. . . . , . . . . .. .~ , ,, 83-3-015 C~ ~4-Laborator~ S udies 1. _ntroduction Study oE anthocyanin formation was undertaken using in vitro systems of selected model crops such as cranberry, apple and poinset-tia in order to investigate:
a) the relative effectiveness of different spectral regions and diLferent irradiance levels, b3 the - red/far red reversibility and the reciprocity relationship, and c) the involvement of phytochrome and the probable contribution of photosynthesis to the red-light mediated HIR response.

2. Materials and Method The plant material included: cranberries, Vaccinium macrocarpon AIT ~obtained from Ocean Spray Company, Middleboro, Mass.); poinsettia, Euphorbia pulcherrima V-1 (obtained from Ecke Nurseries, Encinatas, CA); and a~ples ~ cIntosh," Malus domestica (obtained from the University of Massachusetts Horticultural Research Center, - -Belchertown, MA and Standard Orchards, Hudson, MA). In most cases, apple skin and poinsettia leaf tissue used for experimental purposes were cut into uniform disks (0.5 cm diameter) using a spring-loaded plunger. Disks cut from each group of tissue were put directly into 0.1% HC1 in me.hanol and were immediately frozen in liquid nitrogen, and stored in a freezer.
Experiments were conducted in an environmental cha~er (Con rolled Environments LTD., Winnipeg, Canada) divided into five light--tight modules. Lamps were placed across the top of each module and lighi intensities were controlled by adjusting the distances between the lamps and tissues. The tissues were maintained at 25C to 27C, ancl exposed separately to narrowband liyht at nine wavelengths between 371 nm and 740 nm (irradiance ranqe:
0.01mWtcm to 2mW/cm ) continuously each day.
Narrowband width-emitting fluorescent lamps, having maxima at one of the following wavelengths: 371, 420, . .

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83-3-0]5 CN -5~

44~, 467, 504, 550, 590, 660 and 740 nm (supplied by GTE
Svlvania Ligh~ing L~roducts, Danvers, ~1~), were covered ~in all but the 371 nm lamp) with a 5-mil thickness of Weatherable polyester film (Martin Processing Co., Martinville, VA)~ In addition, plastic filters surrounding the UV prefilter were used to absvrb visible mercury lines not~ in the immediate spectral region of the narrowband emissions. The bandwidths and filters used for each lamp source are known in the art. Anthocyanin was extracted from all tissue using methanol-EIC1 (99:1 v/v).
The extracts were clarified by filtration, and dilutions of the extracts were made within each set of plant tissue with methanol-HCl until the absorbance of the solution could be read in a spectrophotometer at 530 nm and 657 nm.
( 530 0.33 A657) was used to eliminate the contribuiion of chlorophyll and its degradation products in acid solution to the absorbance value at 530 nm.

- 3. Results ~", The action spectra for anthocyanin formation were measured with disks obtained from cranberry -and apple fruit skins, and modified poinsettia leaves. The measurements of the action spectrum were made during the linear period of anthocyanin formation. Representative results obtained in several action-spectr~lm experiments are shown in Fig. 1 which depicts an action spectrum for anthocyanin formation in selected model crops.
Disks were incubated in 0.1 molar sucrose and light of ~ifferent waveleng-ths. Anthocyanin formation is plotted as a function of the wavelength of light used for each incubation. Each point in this plot represents an avera~e OI 15 samples. Each sample consists of 50 disks.
Cranberry skin disks cultured in 0.1 molar sucrose and in 'ight of different wavelengths showed two distinct peaks of anthocyanin biosynthesis, a lower peak at 44~ nm and a higher peak at 660 nm. The action spectrum for anthocyanin formation in poinsetticl leaf and apple fruit ~. _ . .. . . . .. . .. . . ... . . . . .. ..... .. . . . . .. .

~ 37 83-3-015 C~ -6~

skin disks was esserltially the same as the ac-tion spec-trum for cranberry. The most effective light ~avelength for anthocyanin formation in apple disks, however, was blue light with maximum emission peak at 448 nm.
The spectral sensitivity of anthocyanin formation in selected plant species exposed to continuous blue or red radiation depended upon the irradiance and length of exposure.~ In cranberry and apple fruit skin disks, anthocyanin synthesis was fully saturated at an irradiance of 0.82 mW/cm2 under blue, and 1.19 mW/cm2 under red light (Fig. 2). Fig. 2 depicts the effect of light intensity on anthocyanin formation in cranberry (C) and apple fruit (A) disks. Disks cut from fruit skin were immediately transferred to 'che incubation medium and exposed to red tl) and blue (2) radiation at various intensities for 14 hr. The value for each point is an average of five separate experiments done in triplicate ~ statistical - error.
In poinsettia leaf disks, the blue light intensity - 20 required for saturation of anthocyanin was the same as for apple s~in disks. The saturation of red light intensity for anthocyanin formation, however, was almost one-quarter of that required in apple fruit skin disks, as indicated in Fig. 3 which depicts the e~fec-t of light intensity on anthocyanin formation in poinsettia leaf disks. Disks cut from mod~fied leaves were immediately transferred to the incubation medium and exposed to red and blue radiation at various i~tensities separately for 120 hr. The value for each point is an average of five separate experiments done in triplicate ~ statistical error.
'~ith respect to the time courses of anthocyanin synthesis under saturating blue and red radiation in poinsettia leaf disks, it showed an initial lag phase of about 12 hour during which practically no anthocyanin was synthesized. Formation of anthocyanin be~an at the end o~
lag phase and reached steady state by 120 hours and 216 . . .

3~37 83-'-015 CN -7-hours ur-der red and blue radiation, respectively, as shown in Fig. 4, which depicts a time course for an-thoc~anln synthesis in poinsettia leaf disks. Disks cut from modified poinsettia leaves were immediately transferred to the incubation medium and exposed to red (660 nm: 0.30 mW/cm2) and blue (~48 nm: O.S2 mW/cm ) radiation separately at 0 hr, and harvested at indicated times for estimation of anthocyanin content. The value for each point is an average of five separate experiments done in triplicate + statistical error.
In apple skin disks, anthocyanin synthesis showed an initial iag phase of about 24 hours reaching a steady state by about 1~4 hours and 196 hours under saturating blue and red radiation, respectively, as indicated in Fig~
5 which depi~ts a time course of anthocyanin synthesis in apple fruit disks Disks cut from fruit skin were immediately transferred to an incubation medium and exposed to blue (448 nm: 0.82 mW/cm2) and red (660 nm:
1.19 ~W/cm2) radiation separately at 0 hr and harvested at indicated times for estimation of anthocyanin content.
The value for each point is an average of five separate experiments done in triplicate + statistical Standard error.
Since the action spectrum for anthocyanin formation in apple and poinsettia showed the maxima around 448 nm and 660 nm l ght wavelengths, the relative roles of thesP
wavelenyths in anthocyanin synthesis were examined. Data in ~able 1 show the interactive effects of blue and red radiation on apple anthocyanin synthesis. Apple fruit skin disks exposed to continuous blue radiation at ~aturating light intensity formed more anthocyanin than continuous red radiation. Continuous blue light, however, when supplied simultaneously with continuous red radiation formed about 36~ more anthocyanin than continuous blue radiation alone. A similar effect was obser~Ted with continuous b]ue radiation when it was provided with low , .. . . . . . ... . .. . .. . . . . .

12~3~3~

f].uxes of red radiation throughout the irradiation period.
These resul.ts indicate that red ligh-t serves as a trigger for the blue radiation actiny through the "Hiyh Irradiance Reaction" rather vice versa since the pulses of blue light superimposed on continuous red radiation were no-t equally effective.

EFFECT OF RED (660 nm) AND BLUE (448 nm) LIG~IT
TREATMENTS ON ANTHOCYANIN FOR~ATION IN APP~E
. (VAR. "McINTOSH'1) SKIN DISKS
. _ __ _ TREATMENT AMOUNT OF ANTHOCYANIN* .
. (A530 - ' 33A657~
. 72 hr 144 hr Continuous Red (1.19mW/cm2) 0.054+0.003 0.126+0.006 Continuous Blue (0.82mW/cm2) Q.088+0.004 0.197+0.011 Continuous Red (1.19m~/cm2)+ 0.118+0.005 0.269"0.012 20 Continuous Blue (0.82mW/cm2)~ : ~ --Continuous Red (1.19mW/cm2)+ ~0.056+0.002 0~163+0.006 10 min. Blue (0.82mW/cm2) , given every 4 hr ~.
Continuous Blue (0.82mW/cm2)t 0.112+0.006 0.264+0.013 1:0 min. ~ed ~1.19mW/cm2) -given every 4 hr .
*Values are means of five separate experiments done in tri~licate + statistical Standard error.
.. , The interaction of two light wavelengths on anthoc~anin formation in poinsettia leaf disks was somewhat different. As shown in Table 2, the most effective narrowband region was red light peaking at 660 nm. Over si.Y-ty percent increase in anthocyanin formation in leaf disks was observed when continuous blue radiation was supplied wi-th continuous red light. Providing short exposures of blue radiation with cont:inuous red radiation - 1~43~37 83-3-0~5 CN -9-result~d in a formation of an-thocyanin equal to that of continuous blue plus red radiation.

-- - .

. , .
EFFECT OF RED (660 nm) AND BLUR (448 nm) LIGHT
TREATMENTS ON ANTHOCYANIN FORMATION IN
POINSETTIA LEAF DISKS
. _ TREATl~ENT AMOUNT OF ANTHOCYANIN*
. (A530 - O 33A657 ~ 60 hr 120 hr Continuous Red (0.30mW/cm2) 0O119+0.006 0.262+0.01 l Continuous Blue ~0.82mW/cm2) 0.065+0.004 0.15~+0.00 ¦
Continuous Red (0.30mW/cm2~+ 0.187+0.012 0.422-~0.02 Continuous Blue (0.82mW/cm2) ~
Continuous Red ~0.30mW/cm~)+ 0.166+0.011 0.410-~0.028 10 min Blue (0.82m~/cm2) 20 given every 4 hr Continuous Blue (0.S2mW/cm2)+ 0.088+0.006 0.186~0.010 10 min Red (0.30mWtcm2) ~iven every 4 hr *Values are means of five sepz rate experiments done in triplicate + statistical Standard error.

The difference in a mode of action of red light and blue light on anthocyanin appears to be related to the stability of photoreceptor, possibly phytochrome. In apple disks, photoreceptor seems to be relatively unstable, since brief exposures to red radiation were required throughout the blue radiation period. Red radiation alone both activates phytochrome necessary Eor the blue "High Irradiance Reaction" (HIR) and renders possible, at a low level of efficiency, the HIR. In poinsettia disks r the effect of blue radiation on .

.. .. . . ... . . . ... .

~ z~3~
83-3-Ol5 CN -10-anthocyanin fc,rmation, prohably, provides some precursors required for anthocyanln foxmation. It is believed that blue radiation reduces the level of certain speciic inhibitors which interfere with phenylalanine ammonia-lyase, a key enzyme involved with anthocyanin biosynthesis Well-establishea criteria should be satisfied, however t before it can be claimed that phytochrome is involved in a plant system. The fulfillment of these criteria for anthocyanin formation is described in Table 3.

_ I
EFFECT OF BRIEF IRRADIATION OF RED AND FAR-RED
LIGHT ON ANTHOCYANIN FORMATION IN POINSETTIA
LEAF DISKS
_ ~MOUNT OF ANTHOCYANIN*
TREATMENT (A530 ~ 0-33A657 D~rk Control 0.001 10 min R/Day 0.02~
10 min FR/Day 0.001 10 min R -~ 10 min FR/Day 0.001 -10 min FR + 10 min R/Day - 0.023 *Ext-action or anthocyanin was performed five days after the first irradiation. Conventional induction-reversion e~periments demonstrate the involvement of phytochrome in light-mediated anthocyanin formation in poinsettia leaf disks. Values are means of eight separate experimen~s done in triplicate.

The formation of anthocyanin was induced by a brief 10 min exposure to red (R) light given every day and this effect was completely counteracted by immediate and subsequent exposures to 10 min of far-red (FR) li~hts. The induction by a sinyle, hrief, low irrad ance treatment and re-l/far-red reversi~le reaction provided ~vidence that ~3~
83-3-0l5 CN -11-phytochrom~ was at least one of the pho-toreceptors involved in an-thocyanin formation~
As indicated iII Table 4, by reciprocal changes of the .irradiance and duration of irradiance, it is demonstxated that anthocyanin formation in poinsettia disks obeys the reciprocity relationships and this response is a function of the dose lIxt~ rather than that of the irradiance alone. The validity of khe reciprocity relationships indicates the involvement of only one photoreceptor in photocontrol of anthocyanin synthesis.

TABLE 4 _ _ RELATI~NSHIP BETWEEN IRRADIANCE AND TIME REQUIRED
FOR PHOTOPROMOTION OF ANTHOCYANIN FORMATION IN
POINSETTIA LEAF DISKS
.
RED LIGHT AMOUNT OF ANTHOCYANIN*
IRRADIAN~E (I) (A530 ~ A-33A657 .. AFTER IRRADIATION FOR:
. _ 20_______. 240 hr 120 hr 60 hr 600 0.256 + 0.013- - 0.268 + 0.015~ 0.262 + 0 014 300 ~ 0 249 ~ O.0~5 ~ O.265 + 0.011 -0.119 + 0 006-~

150 -~ O 251 + 0 012 ~0.123 + 0.005 ~ 0.062 + 0.00~
~*Values enclosed in dashed lines represent equal light doses, i.e., Ixt = constant, where I is irradiance and t is time. Values are means of five separate exper.iments done in triplicate + s.e. _ The quantity of anthocyanin formed in response to a brief irradiance is relatively sma]l and maximum production requires prolonged exposure to red light .... . . .. . ... . , . . .... . . . . . , . ... .~ . .. .

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(Table 5). The former response was identified as the low enerqy red/far-red reversible phytochrome reaction, while the latter was considexed as the high energy reaction, also called high irradiance reaction system of plant photomorphogenesis. The latter response suggested light duration dependence of phytochrome interaction or the possible existence of a secon.d photochemical system besides phytochrome, particularly photosynthesi.s.

EFFECT OF DURATION OF RED LIGHT EXPOSURE ON
ANT~OCYANIN FOR~TION IN POINSETTIA LEAF DISKS
.
TREATMENT : ~OUNT OF ANTHOCYANIN*
_ - - (A530 ~ 0'33A657 10 min R/Day** 0.024 + 0.001 (660 nm: 0.30 mW/cm2) 120 hr R 0.265 + 0.010 20 (660 nm: 0.30 mW/cm2) .
*Values are means of eigh : separate experiments done in triplicate T statistical Standard error.
**E~traction of anthocyanin was performed five days after the first irradiation treatment.

In order to determine if photosynthesis contributes to reQ-light mediated HIR response in the enhancement of a~thocyanin formation in poinsettia di.sks, studies were conducted using various inhibitors of photosynthetic photophosphorylation and chlorophyll synthesis. Table 6 shows the effect of cyclic and noncyclic photosynthetic inhibitors on anthocyanin syn-hesis. Poinsettia leaf disks were incubated with four inhibi-ors separately over a period of ti~e under 660 nm light. None of the inhibitors, such as 3- (3, -4 dichlorophenyl) -1, dimethylurea (DC~IU), ammonium sulphate (N~l~)2SO4 of 1 ~ 7 noncycl,ic photophospho:rylation and dinitrophenol lDMP) arld antimycirl-A (ANT-A) inhlhited the light-medi.atecl anthocyanin formation.
TABLE 6 _~
. _ __ EFFECT OF PHOTOSYNTHETIC INHIBITORS ON ANTHOCYANIN
. FO~TION IN POINSETTIA LEAF DISKS

T~EATMENT - ¦ - AMOUNT OF ANTHOCYANIN8 CONCENTRATION¦ (A530 ~ O33A657 _ (M) ¦ DCMU (NH4)2SO4 DNP ANT-A .

O 0... 26Ba o.261a 0.249a 0.253a 10-5 0.261a 0.267a 0.256a 0.254a 10 3 0.264a 0.259a 0.252a 0.249' *DCMU, 3-(3, -4 ~chlorophenyl)-1, DimethyIurea; DNP, Di'nitrophenol; (NH 7 2SO~, A~onium sulfate; ANT-A, Antimycin A.
Di,sks were exposed to red light at 660 nm (0.30 mW/cm2) for five days. Controls kept in 0.lM sucrose solution.
Va~lues are means of five separate experiments done in triplicate. Me~ns followed by identical postscripts within each column are not significantly different for .¦ nthocyan,in values.p,'~0'.05. - - - ~ .

Similarly, streptomycin (STM) and chloramphenicol iCHP), inhibitors of chloroplast development and chlorophyll syn'hesis at two different (10 ppm and 100 ppml concentrations had no effect on anthocyanin synthesis (Table 7).

, . ... . . . .. . . . .. . . . ... . .. ... . .. .. .. .. .

83~3-015 CN -:l4-¦ TAB].E 7 ACTION OF STREPTOMYCIN (STM) AND CHLOR~MPHENICOL (CHP) ANTIBIOTICS ON
ANTHOCYANIN SYNTHESIS IN POINSETTIA LEAF DISKS
; AMOUNT OF ~NTHOCYANIN*
TREATMENT - : (A530 ~ 0-33A657 CONCENTRATION : .. :
STP~ ~._ .
. 0 0.265a 0.258a 0~ 259a O. 267a , 100 0.268a 0.2S2a *Disks were exposed to red light at 660 nm (0.30 mW/cm2 for five days. Control disks were incubated in 0.1M
sucrose solution. Values are means of five separate experiments done in triplicate. Means followed by idelltical postscripts within each column are not sig-.. nif.icantl.y..different.for anthocyanin values, p<0.05.

The basic features of phytochrome response such as the relative eEfectiveness of different irradiance levels, red/far-red reversibility and the validity of the reciprocit~ relationships of the response were not affected by antibiotics. The ratios of the levels of anthocyanin produced after a ten minute red, and a ten minute redilO minute far-red treatment were the same in the incubation medium containing inhibitors as was observed with the control (Table 8). These findings indicate that photosynthesis does not play any role in red-light dependent anthocyanin formation, and the effect of red radiation on anthocyanin synthesis and photosynthetic development are independent of each other.

"

. . . ~ - . -- . . . . .

~1.2~ 37 TABL~ 8 ______ _ _ . __ INFLUENCE OF STREPTOMYCIN (STM) AND CHLOP~MPHENICOI, (CHP) ON THE R-FR REVERSIBILITY OF ANTHOCYANIN
FORMATION IM POINSETTIA LEAF DISKS
_ AMOUNT OF ANTHOCYANIN*
TREATMENT (A530 ~ 0-33A657~
Control STP CHP
(0.lM sucrose) (100 ppm) (100 ppm) Dark Control 0.001 0.001a 0.001 10 min R/Day 0.024b 0.025b 0.024b 10 min FR/Day 0.001 0.001a 0.001a 10 min R + 10 min 0.001 0.001a 0.001 FR/Day 10 min FR + 10 min 0.023b 0.024b 0.023b R/Day *Extraction of anthoc~ anin was performed five days after the first irradiation. Values are means of three separate experiments done in triplicate. Means followed by nonidentical postscripts within each column differ significantly for anthocyanin values, p~0.05.

4. Discussion The action spectra for anthocyanin formation in cranberry, apple fruit skin and poinsettia leaf disks shows two m~xima, one in the blue and the other in the red region of the visible spectrum (Fig. 1). The spectral sensitivity and -the irradiance dependence of anthocyani synthesis in tissues exposed to continuous irradiation depends upon the length of exposure (Figs. 2 through 5).
Thus, anthocyanin synthesis is controlled by high irradiance reactions, operated throu~h the interactions of phytochrome with other HIR photoreceptors.
Red light was effective in stimulating anthocyanin formation and this effec-t was nullified when red light was - - - . .

followed i.l~nedi.ately by far-red light. Such reversibility was obtained with short ligh-t periods clearly indicati.ny the involvement of phytochrome (Table 3) Field Studies 1. Apples a. Night-break liyht treatment Apples tvar. "~cIntosh", "Red delicious") on trees exposed to night-break light treatment (high intensity discharge and/or VHO narrowband fluorescent lamps: 1~/cm2 to 200~W/cm2, one quarter hour per day) for 40 days prior to harvest show improvement in anthocyanin formation as compared to control (not receiving nigh-t-break exposure) groups.
Referring to Table I, which tabulates the effect of night-break light treatment on apple red coIor development at the time of harvest, there is listed various data comparing control vs. lighted crops for McIntosh apples for t.he years 1977 and 1978, Red delicious apples for 1978-1980 for Washington State and California. Note that in 1977/ with trees exposed to night-break lighting for 30 days prior to harvest, the percent red color for the apples showed an improvement, from 73.8 percent to 78.3 percent (a 4.5 percent increase). In 1978, with a 30 day exposure, the lighted group showed an improvement over control of 62.8 percent vs. 53 percent (a 9.8 percent increase).
The disparity among annual data is due, in part, to the fact that two annual seasons are not identical, as to temperature, humidity, rainfall, insect infiltration, and the like.
The light applied was a combination of continuous blue and continuous red lights having maximum emission peaks centered around 448 nm and 660 nm, respectivPly.
The Red delicious apples were in Wenatchee, Washington in 1978 and in Linden, California in 1979 were exposed over a 45 day period, one-quar-ter hour per night, . . - - : . .

. lL29~3~3~7 showing an improvement, over control, of 9.2 and 7 percent, resp-ectively. The tests were repeated the followins year, with 40 day exposure showing an improvement of 9.2 percent and 12.5 percent, respecti~Tely.

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The eEfec-ts oE night-break treatment on apple (var.
"Red Delicious") harvest growth and quality in 1979 at Wenatchee, Washington is tabulated in Tab].e II below.
Comparison is shown among control, apples treated with alar, and night~break treatment at two different dosage values.
In particular, the results show that night-break lighting improves percentage red color over both control and alar groups. The percentage of total solids, and the dry weight of the apples, also showed improvement.

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3~37 Ethrel, a chemical growth regulator which is commercially us2cl for red coloration of apples, produce~
apples having poor storage characteris-tics. In contrast, apples exposed to night~break light treatment of blue and red lights yield good storage quality characteristics, as shown in Table III below:

TABLE III
_ , EFFECT OF NIGHT-BREAX LIGHT TREATMENT ON HAP~VEST APPI,E
FRUIT (VAR. "RED DELICIOUS" - TOP RED) QUALITY
~ (LINDEN, CA) 198Q
_ l Treatment Av. Color Avo Firmness Av.% Storage ~uality (%)(lbs.) ¦Solids Characteristicc ., Control 47O5 18.70 11.93 Good Lighted 60 18.79 11.5~ Good 20 Ethrel* 50 17.04 13.77 Poor California Apple grower's 18 to 19 11 to 12 "Standards *Ethrel is a chemical growth regul ator, us ed commercially or red coloration of apples.

Night-break light treatment of apples (var. "Red Delici~us") prior to harvest had VàriOI1S benefits compared to "control" app]es which were not provided with night-break lights. The lighted apples, as shown in Table IV were more likely to be of consumer grade, (U.S. Extra Fancy or Fancy)have a higher percentage of solids, be heavier, longer, have a higher percentage of red color, and have an increase in tree trunk growth.

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~3-3-015 C~' -23-The night break light treated apples retained the firmness of "control" apples, retained the good storage characteristics of control apples, had a higher percentage of solids than control apples, and had a higher percentage of red color. In contrast, ethrel treated apples were less firm, less solid, and had poor` storage characteristics, as shown in Table V.

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83-3-015 ~N -25-b. After harves-t con-tinuous lighting Table VI tabulates the percentaye of red color of "Red delicious" apples at Linden, Cali~ornia in 1979 under control conditions and lighted conditions.
Prior to harvest, the lighted apples were exposed to four hours (from 10 pm to 2 am) of continuous red (peak emission at 660 nm) and blue (peak emission at 448 nm) at about 100~W/cm2. After harvest the lighted apples were continuously exposed to 660 nm light (about 100~W/cm2) for four days, while the apples were held in cold storage.

¦ _ TABLE VI _ _ ¦EFFECT OF NIGHT-BREAK LIGHT TREATMENT ON APPLE RED COI.OR
- DEVELOPMENT, "RED DELICIOUS", LINDEN, CA., 1979 PERCENT RED COLOR
-28 35 HARVEST ~AFTER H~RVEST 4 DAYS

~ ~ STORAGE*

- Night-~ ,reak treatment was co mmenced on July 3, 1979 Trees were exposed to red (660 nm) and blue (448 nm) iights (-100~W/cm2) for 4 hrs (10 p.m. to 2 a.m.) per nigh,.
*After harvest, fruits were held in regular cold l10C) storage. The lighted group were exposed immediately to con-tinuous 660 nm light t~l00~W/cm 2) for four days. Fruits were graded for color after four days.

2. Grapes Grapes (var. "Emperor") on vines were exposed to night-break light treatment (HID and naxrowband fluorescent lamps: l~W/cm2 to 200~W/cm2 for one to four hours yer clay ror 40 clays prior to harvest. Impro~jremen-t in anthocyanin format.ion was shown, as compared to contro:L
(not receiving night-break treatment), as shown in Table VII.
Fruit growth (si~e) and quality (flesh firmness, solids and storage-life) at the time of harvest were not affected adversely by night-break light treatment.
Similarly, the terminal shoot growth and fruit bud development was normal.

-TABLE VII
EFFECT O~ NIGHT-BREAK LIGHTING TREATMENrT ON SUGAR :
ACCUMULATION AND ANTHOCYANIN FORMATION IN GRAPES
(VAR. "EMPEROR") _ : AVERAGE .
TREA~MENT PERCENTAGE ANTHOCYANIN .

_ SUGAR IN~ENSITY
Control 14 +
Ethrel : 15.~ ~++~+_ Red Light 15.9 . ++~
Blue Light 15.4 ++
Red & Blue Light 15.3 +++
Red Light & Ethrel 16.93 : ++++_ ~lue Lisht & Ethrel 16.23 ++++_ Red & ~lue Light & Ethrel 16.30 +~++-_________________________ _______________ _____________.
Data Collection - two weeks prior to harvest -~ Indicates (10-20%) pink colo.r of berries ++ Indicaces (30-45%) pink color of berries +++ Indicates t50-75%) pink color of berries ++++ Indicates (S0-99%) pink color of berries 30- Indicates softening and deep brown red coloration .of berries (not corNmercially desirable features~
. I . . ~ ~ ..... .. . . . ........ ... .. ..... . .
. ~

.

~3~37 Conclusions ~ se oE a specific lighting system should help considerably in improvement of color of fruit and ornamental crops (either exposure of produce under s-torage or yreenhouse and field conditions) without causing either any phytotoxicity or adverse effects on normal growth and development of trees.
Through the practice of this invention, color of fruits under regular cold storage greenhouse, and field conditions can be improved using specific light treatments without causing any adverse effects on plant grow-th and development. The integrity of fruit storage quality features can be maintained, and the environment kept free from hazardous chemical residues. APP1QS taken from regular cold storage can be light-treated at any time before and after harvest with no subsequent fading of color.

! i

Claims (3)

THE EMBODIMENT OF THE INVENTION FOR WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED IS DEFINED AS FOLLOWS:

1. A method of improving anthocyanin formation in apples that have been harvested comprising continuously exposing said apples, while said apples are in a regular cold storage, with red light having a maximum emission peak centered around 660 nm.

2, The method as recited in claim 1 wherein said apples are continuously exposed for a period of four days.

3. The method as recited in claim 1 wherein the temperature of said regular cold storage is about 10°C.