JP5076114B2 - Citrus moisture control cultivation method and citrus moisture stress measuring instrument - Google Patents

Description

  The present invention relates to a citrus moisture control cultivation method and a citrus moisture stress measuring instrument that can be used therefor.

  Conventionally, in the cultivation of citrus fruits such as Wenzhou mandarin orange, it is known that water management such as irrigation and draining (restriction of irrigation) is effective in order to produce fruits with a high sugar content. Specifically, it has been proposed to restrict irrigation from the latter half of the fruit growth to the maturation period and to give a moderate water stress to the tree.

  As a method for artificially restricting irrigation, a method of cultivating in a greenhouse is known. However, house cultivation is not so popular because it requires considerable labor for temperature management and moisture management in the house in addition to the high construction cost of the greenhouse.

  On the other hand, it is impossible to control rainfall in outdoor cultivation. Therefore, fruit quality was influenced by the pre-harvest weather.

  Then, the cultivation method as described in patent document 1 (Unexamined-Japanese-Patent No. 5-15262) etc. is proposed. Specifically, it is a cultivation method in which soil moisture is managed by covering the soil surface from the latter half of the fruit growth to the maturity stage with a waterproof film having air permeability.

  However, even if soil moisture is managed by the cultivation method described in Patent Document 1, the producer must determine whether or not moderate moisture stress is applied to the tree body. And when an excessive water stress is given to a tree, the momentum of a tree will be reduced. As a result, fruit growth is inhibited, and growth of new branches and shoots in the following year is inhibited. In the worst case, the tree itself may die. Therefore, the determination of whether or not water stress is appropriate is extremely important.

  In this regard, as an indicator of moisture stress, changes in appearance such as the degree of leaf winding, leaf color, and fruit enlargement can be mentioned. And conventionally, the producer judged the water stress from such changes in appearance, and determined the irrigation time and irrigation amount.

  However, such a method for determining moisture stress requires skill and cannot be performed by anyone. In addition, it is necessary to appropriately correct the judgment in consideration of the influence of actual weather, and it tends to depend on intuition and experience. Therefore, there were variations and uncertainties in judgment.

  Patent Document 2 (Japanese Patent Laid-Open No. 2005-308733) discloses a method for quantitatively measuring water stress of agricultural products such as mandarin oranges by spectral analysis from the color of the leaves. However, there is a problem that the apparatus used for measurement is complicated and expensive, and it is difficult to easily measure moisture stress.

JP-A-5-15262 JP 2005-308733 A

  Here, the present invention has been made in the background as described above, and the problem to be solved is to provide an appropriate water stress to improve the quality of the fruit. It is providing the moisture control cultivation method of a citrus fruit, and the water stress measuring instrument of a citrus fruit.

  Hereinafter, the aspect of this invention made | formed in order to solve such a subject is described. In addition, the component employ | adopted in each aspect as described below is employable by arbitrary combinations as much as possible.

  The present invention relating to a citrus moisture control cultivation method is a citrus moisture control cultivation method in which the surface of farmland is covered with a breathable waterproof sheet and an irrigation system is provided, and the soil moisture is controlled and cultivated. , By touching the hardness of the fruit with fingers, using a synthetic resin fruit model that imitates the fruit, comparing the feel of the hardness in the fruit and fruit model to determine the suitability of moisture stress in the fruit tree, It is characterized by controlling soil moisture based on the judgment result.

  According to such a citrus moisture control cultivation method according to the present invention, the suitability of moisture stress in fruit trees can be determined by a very simple method of comparing the feel of the fruit model and the hardness of the fruit. This makes it possible to easily determine whether water stress is appropriate.

  Therefore, in the water control cultivation method of citrus fruits according to the present invention, appropriate water stress is applied to fruit trees by accurately determining the appropriateness of water stress in fruit trees, such as by frequently determining the appropriateness of water stress. It becomes possible to give. As a result, the fruit quality can be improved.

  In the present invention relating to the moisture control cultivation method of citrus fruits, a system comprising various conventionally known facilities can be adopted as the “irrigation system”. For example, a drip method (drip method) described in JP-A-2005-204662, etc. The irrigation system of formula) is preferably employed, but is not limited thereto. For example, in addition to laying a water pipe for irrigation on the ground surface, the water pipe for irrigation is buried in the ground and a liquid outlet is installed in the ground, or a water pipe for irrigation is installed above the ground in the air. The liquid outlet can also be installed in the air. In addition to an irrigation system that discharges water or the like from an outlet of a water pipe, it is possible to employ an irrigation system that uses a sprinkler or the like to spray. Furthermore, the adjustment of the irrigation amount in such an irrigation system can be freely set under various conditions and is not limited. For example, as described in JP-A-2002-300818, etc. In addition to adjusting the irrigation accordingly, it is also possible to adjust the irrigation based on the detection signal using a sensor that detects the moisture and temperature of the soil. Moreover, when irrigating with an irrigation system, not only water but liquid fertilizer etc. can be given suitably.

  Further, in the present invention relating to a citrus moisture control cultivation method, when “controlling soil moisture”, irrigation with the irrigation system described above, irrigation with the irrigation system is stopped, or the amount of irrigation with the irrigation system is adjusted. It is not limited to doing. For example, soil moisture may be controlled by specially irrigating with a means (for example, a bucket or a hose) separate from the irrigation system. In addition, soil moisture may be controlled by rolling rain-proof waterproof sheets and applying rainwater.

  Furthermore, in the present invention relating to the moisture control cultivation method for citrus fruits, the fruit model that imitates the fruit is made to have substantially the same conditions that affect the feel when comparing the feel of the fruit and the hardness of the fruit model. Because. Therefore, elements that do not affect the feel of hardness, specifically, color, water content, material, etc. may differ from the fruit, and the fruit model in which they differ also mimics the fruit in the present invention. is there. It should be noted that in the fruit and the fruit model, the mass does not necessarily directly affect the tactile sensation of hardness, and therefore it is not necessarily required to be substantially the same.

  Then, in the moisture control cultivation method of citrus fruits according to the present invention, fruit models are prepared by preparing a plurality of fruit models with different hardnesses, and comparing the hardness of the plurality of kinds of fruit models and the fruit according to the tactile sensation. The mode of determining the suitability of moisture stress in is preferably employed.

  According to this aspect, it is possible to set a plurality of criteria for comparing hardness by tactile sensation. Thereby, it becomes possible to compare the hardness of a fruit with some evaluation criteria. As a result, it is possible to improve the accuracy of determination as to whether or not moderate moisture stress is applied to the fruit tree. That is, as compared with the work of using only one fruit model of a single hardness and judging whether or not the hardness of the fruit is equal, a plurality of fruit models are prepared and any fruit model is The work of judging whether the hardness is the closest is easy and quick because of the characteristics of human touch, and can be judged accurately.

  Further, in the moisture control cultivation method of citrus fruits according to the present invention, a mode in which the judgment of the suitability of moisture stress in fruit trees based on a comparison of the hardness due to the tactile sensation between the fruit model and the fruit is suitably employed after sunset. The According to this aspect, the difference in the hardness appearing in the fruit is easily made depending on the degree of moisture stress. As a result, it is possible to further improve the reliability of determining whether water stress is appropriate in fruit trees.

  On the other hand, the present invention relating to a citrus moisture stress measuring device is composed of a combination of a plurality of types of fruit models each formed of a synthetic resin material, imitating fruits in the citrus vacuole development stage, and having different hardnesses. It is characterized by the fact that the hardness of these multiple types of fruit models is set to simulate the hardness that appears in the fruit according to the degree of moisture stress applied to the fruit tree during fruit cultivation.

  In such a citrus moisture stress measuring device structured according to the present invention, it is possible to judge the suitability of moisture stress in fruit trees by a very simple method of comparing the feel of the fruit model and the hardness of the fruit. . As a result, it is possible to easily determine the suitability of moisture stress in fruit trees.

  Accordingly, in the citrus moisture stress measuring instrument according to the present invention, a plurality of fruit models are provided, and the plurality of fruit models have different hardnesses. Thereby, it becomes possible to compare the hardness of a fruit with several fruit models. As a result, it is possible to improve the accuracy of determination as to whether or not an appropriate moisture stress is applied to the fruit tree.

  Each fruit model is shaped like a fruit. Thereby, it becomes possible to make the conditions in the hardness comparison by the touch of a fruit model and a fruit substantially the same. As a result, the reliability with respect to the accuracy of judgment can be further enhanced.

  In the present invention relating to a citrus moisture stress measuring instrument, “simulating fruit” is defined in the same manner as “simulating fruit” in the present invention relating to the above-described water-controlled cultivation method of citrus fruits.

  Furthermore, in the citrus water stress measuring instrument according to the present invention, the plurality of fruit models include a reference fruit model simulating the hardness that appears in the fruit under an appropriate water stress, and a reference fruit model. Includes at least two of a high-standard fruit model that mimics the hardness that appears in fruits when moisture stress is strong, and a low-standard fruit model that simulates the hardness that appears in fruits when moisture stress is weaker than the standard fruit model It is desirable that This makes it easy to determine whether or not irrigation is necessary. That is, it is easier to determine which of the hardnesses of a plurality of fruit models is easier than the determination of hardness using only one fruit model of a single hardness. In particular, by selecting at least two fruit models from among three types of moderate water stress, excessive water stress, and insufficient water stress, it is possible to make such a determination more easily and quickly. It becomes possible. More preferably, all three types of fruit models with hardness are combined and adopted as a set, and the tactile sensations with the fruits are compared with each other.

  Furthermore, in the citrus moisture stress measuring device according to the present invention, it is desirable that a hardness identifying means for identifying the hardness of a plurality of fruit models from the appearance is provided. Thereby, an appropriate fruit model can be selected easily.

  Therefore, it is desirable that the hardness identifying means is configured by coloring a plurality of fruit models in different colors. Thereby, discrimination power can be given to each fruit model, without affecting the hardness, shape, size, etc. of the fruit model.

  Moreover, in this invention, it is desirable that the connection member which connects a some fruit model is provided. Thereby, a some fruit model can be handled collectively.

  Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a citrus moisture stress measuring instrument 10 as one embodiment of the present invention. The moisture stress measuring device 10 includes a plurality (three in the present embodiment) of fruit models 12.

  More specifically, each fruit model 12 has a shape imitating a fruit in a citrus vacuole development period, and is formed of a synthetic resin material. In addition, as a synthetic resin material, what has elasticity is employ | adopted suitably. For example, silicone or the like can be employed. Moreover, in this embodiment, each fruit model 12 was shape | molded using the shaping | molding die made from the actual fruit. In addition, each fruit model 12 may have a spherical shape having an outer diameter dimension substantially the same as the outer diameter dimension of the equatorial plane of the fruit in the citrus vacuole development period.

  There, each fruit model 12 has different hardness. The difference in the hardness of each fruit model 12 is set to such an extent that a person can understand it by grasping it by hand. Specifically, the hardness of each fruit model 12 is set by imitating the hardness that appears in the fruit according to the degree of moisture stress given to the fruit tree during the cultivation of the fruit. In particular, in the present embodiment, one of the three fruit models 12 is the reference fruit model 14 that simulates the hardness that appears in the fruit in a state where an appropriate moisture stress is applied. The hardness of the reference fruit model 14 is preferably set to 68 ° to 75 °, more preferably 70 ° to 73 ° when the equatorial plane is measured with a durometer ESE type (conforming to JIS K 6253 type E). Has been. In addition, one of the remaining two fruit models 12 is a high standard fruit model 16 simulating the hardness that appears in the fruit in a state where moisture stress is stronger than the standard fruit model 14. The hardness of the high reference fruit model 16 is preferably set to 58 ° to 65 °, more preferably 60 ° to 63 °, when the equator plane is measured with a durometer ESE type. Furthermore, the other is a low standard fruit model 18 simulating the hardness that appears in the fruit when the water stress is weaker than the standard fruit model 14. The hardness of the low standard fruit model 18 is preferably set to 78 ° to 85 °, more preferably 80 ° to 83 °, when the equatorial plane is measured with a durometer ESE type. That is, the three fruit models 14, 16, and 18 show different water stress states. Therefore, as for the three fruit models 14, 16, and 18 employ | adopted, it is desirable for the difference of the hardness between each other to be set in the range of 5 degrees-15 degrees. That is, the hardness difference between the standard fruit model 14 and the high standard fruit model 16 is in the range of 5 ° to 15 °, and the hardness difference between the standard fruit model 14 and the low standard fruit model 18 is in the range of 5 ° to 15 °. It is desirable to make it. This is because a hardness difference of less than 5 ° may be difficult to immediately discriminate due to a direct human touch, whereas a hardness difference of more than 15 ° may reduce the determination accuracy.

  In addition, although it is not clear on drawing, in this embodiment, the mutually different coloring is given with respect to the three fruit models 14,16,18. Thereby, discriminating power is given to each fruit model 14,16,18. That is, in this embodiment, the hardness identification means is comprised by giving different coloring with respect to the three fruit models 14,16,18.

  Moreover, in this embodiment, the three fruit models 14, 16, and 18 are connected by the connection tube 20 as a connection member. The connecting tube 20 is made of a plastic material and extends straight with a substantially constant cross-sectional shape. In this embodiment, polyethylene is adopted as a material for forming the connection tube 20. Further, the connecting tube 20 has an outer diameter dimension that does not affect the hardness of the fruit models 14, 16, 18.

  Such a connection tube 20 is assembled to the three fruit models 14, 16, 18 so that the three fruit models 14, 16, 18 are skewered. As a result, the three fruit models 14, 16, and 18 are connected by the connecting tube 20. As a result, the three fruit models 14, 16, 18 can be handled together.

  Therefore, in this embodiment, the three fruit models 14, 16, and 18 connected by the connecting tube 20 are the low reference fruit model 18, the reference fruit model 14, and the high reference fruit model 16 in this order. They are arranged from one end side in the longitudinal direction to the other end side. That is, the three fruit models 14, 16, and 18 indicate that the moisture stress increases as going from one end in the longitudinal direction of the connecting tube 20 to the other end.

  In the present embodiment, a locking ring 22 as a ring-shaped member is provided at the other end in the longitudinal direction of the connecting tube 20. Thereby, the moisture stress measuring tool 10 can be suspended and stored.

  In the moisture stress measuring device 10 having such a structure, the hardness of the fruit models 14, 16, and 18 corresponds to the moisture stress in the fruit tree. Therefore, by grasping and comparing the fruit and the fruit models 14, 16, 18, it is possible to determine the suitability of moisture stress in the fruit tree.

  In particular, in this embodiment, since three fruit models 14, 16, 18 set to different hardnesses are provided, three different levels are shown as the degree of moisture stress in fruit trees. Become. Therefore, it is possible to improve the reliability for determining whether water stress is appropriate.

  In the present embodiment, the three fruit models 14, 16, and 18 can be identified by giving different coloring to the three fruit models 14, 16, and 18, respectively. Therefore, discriminating power can be imparted to each fruit model 14, 16, 18 while avoiding the influence on the shape, size, and hardness.

  And the water stress measuring instrument 10 made into the above structures can be used for the cultivation method of citrus fruits which controls irrigation. For example, the surface of farmland can be covered with a breathable waterproof sheet, and an appropriate irrigation system such as a drip type (drip type) can be provided to control the soil moisture for cultivation.

  Specifically, in the citrus vacuole development period, the fruit models 14, 16, 18 are compared with the feel of the hardness of the fruit to determine whether water stress is appropriate in the fruit tree. For example, if the fruit is softer than the irrigation reference fruit model 14 and if it is determined that the water stress in the fruit tree is appropriate, the fruit and the irrigation reference fruit model 14 are grasped and compared, and the hardness of the fruit is compared with the irrigation reference fruit model. If it is softer than the model 14, it is determined that the water stress in the fruit tree is appropriate.

  At that time, the accuracy of judgment can be increased by comparing the hardness of the fruit with the other fruit models 16 and 18. Specifically, when the determination criteria for moisture stress are set as described above, it is understood that the hardness of the fruit is softer than that of the reference fruit model 14 by comparing the fruit with the high reference fruit model 16. It becomes easy. Further, if the fruit and the low standard fruit model 18 are grasped and compared, it becomes easy to understand that the hardness of the fruit is harder than that of the standard fruit model 14.

  It should be noted that the criterion for determining water stress may be set between the two fruit models 12, for example, between the reference fruit model 14 and the low reference fruit model 18, or between the reference fruit model 14 and the high reference fruit model 16. . Also in this case, the accuracy of judgment can be increased by gripping and comparing the fruit with the two fruit models 12.

  And based on this judgment result, soil moisture is controlled. For example, if the water stress is appropriate or excessive, the fruit tree is irrigated by the irrigation system, and if the water stress is insufficient, the fruit tree is not irrigated and waits until the water stress becomes appropriate.

  In such a citrus moisture control cultivation method, it is possible to accurately determine the suitability of moisture stress in the fruit by an easy method of comparing the fruit model 14, 16, 18 and the feel of the fruit hardness, Soil moisture can be controlled accurately. As a result, it is possible to improve the quality of the fruit by applying an appropriate moisture stress.

  Further, when the moisture stress measuring instrument 10 as described above is used, since the plurality of fruit models 14, 16, 18 have different hardnesses, when comparing the grip between the fruit and the fruit models 14, 16, 18, The fruit hardness can be compared with several fruit models 12. As a result, it is possible to improve the reliability of determining whether water stress is appropriate.

  Furthermore, if the determination of the suitability of the water stress is made after sunset, the difference in the tactile sensation of the fruit due to the water stress becomes clear, so that the reliability for judging the suitability of the water stress can be further improved.

  First, it was examined whether or not there was a correlation between the hardness felt by the hand and the measurement result by the durometer. Specifically, fruits were collected from each of the 24 fruit trees, and the firmness of the fruits was examined indoors by hand feel and durometer. The survey was conducted from August to mid-September 2007 (August 2, 8, 9, 14, 15, 21, 22, 22, 30, September 5, and 13 , 19) at around 5 o'clock (early morning), around 13 o'clock (daytime) corresponding to sunrise, and around 18:30 (after sunset) when direct sunlight was no longer applied. Moreover, the measurement by a durometer was performed by measuring the equatorial plane of a fruit with a durometer ESE type. On the other hand, the hardness felt by the hand of the fruit was evaluated in five levels by gripping the fruit with the hand and feeling with the fingertip. Specifically, “5” indicates that the object is hard and hardly dents even if it is gripped, “3” indicates that it is slightly soft and slightly different from “5”, and “3” indicates that the difference is slightly soft. It was set to “1”. FIG. 2 shows the correlation between the hardness felt by the hand and the measurement result by the durometer, obtained by such investigation. Moreover, the change in the hardness of the fruit was measured from August 21 to 22, 2007. The result is shown in FIG.

  As is clear from FIG. 2, a high correlation is seen between the hardness felt by the hand and the measurement result by the durometer. Further, as is apparent from FIG. 3, even when the change from early morning to after sunset is observed, the hardness felt by the hand and the measurement result by the durometer show a similar transition.

  Next, we examined the best time to use fruit hardness as an indicator of water stress. Specifically, three fruits were collected from three of the fruit trees that had been subjected to moisture management, and the hardness, coloring ratio, and flesh color of the fruits were measured indoors. This survey was conducted from August to mid-September 2007 (August 2, 8, 9, 14, 15, 21, 21, 22, 30, September 5, 13, 19 Day) at around 5 o'clock (early morning) corresponding to sunrise. Wet management was performed by irrigating 50 liters per fruit tree at intervals of 1-2 days. The hardness of the fruit was measured by measuring the equatorial plane of the fruit with a durometer ESE type. The hardness felt by the hand of the fruit was evaluated based on the hardness of the fruit held by the hand and felt by the fingertips in five levels. The evaluation criteria are the same as in the previous test. The results obtained from this investigation are shown in FIGS. In addition, FIG. 4 has shown the survey result in the very early-growth Wenzhou, and FIG.

  As is clear from the results of FIG. 4, in the wet-managed fruit trees of the very early-growth Wenzhou, the fruit hardness was almost flat until the end of August, but in September, the fruit coloring and flesh color changed. As it progressed, it softened rapidly. In other words, in the very early Wenzhou, the fruit hardness is hard and stable until the end of August. Therefore, in the extremely early-growth Wenzhou, fruit hardness can be used as an indicator of moisture stress until late August.

  In addition, as is clear from the results of FIG. 5, in the wet management fruit trees of early-growth Wenzhou, the fruit hardness was almost flat until the beginning of September, but the flesh color progressed in the middle of September. It suddenly softened. In other words, in early-season Wenzhou, the fruit is hard and stable until early September. Therefore, in early-growth Wenzhou, fruit hardness can be used as an indicator of moisture stress until early September.

  Next, the relationship between fruit firmness and water potential was investigated. Regarding the hardness of the fruit, it was collected at around 5 o'clock (early morning) corresponding to the sunrise, around 13 o'clock (daytime), and around 18:30 (after sunset) when it was no longer exposed to direct sunlight. The hardness of Wenzhou fruit was examined indoors with hand feeling and durometer. The water potential was measured early in the morning in the field. The survey was conducted from August to mid-September 2007 (August 2, 8, 9, 14, 15, 21, 22, 22, 30, September 5, and 13 , 19). The measurement of fruit firmness is carried out only in the early morning. Moreover, the measurement by a durometer was performed by measuring the equatorial plane of a fruit with a durometer ESE type. On the other hand, the hardness felt by the hand of the fruit was evaluated in five levels by gripping the fruit with the hand and feeling with the fingertip. The evaluation criteria are the same as in the previous test. The water potential was measured by the pressure chamber method.

  In the present invention, “sunset” refers to the time when the trees are no longer exposed to direct sunlight. In the present invention, the term “after sunset” preferably refers to the range from sunset to 2 hours, more preferably from 10 minutes to 1 hour after sunset. Immediately after being covered and exposed to direct sunlight, there is an influence of heat etc. due to the direct irradiation of sunlight until then, after 2 hours from sunset, time has passed too much, This is because the measurement accuracy also tends to decrease. Incidentally, 18:30 is the time when the tree is no longer exposed to direct sunlight.

  And based on the result of the above-mentioned investigation, the relationship between the water potential and fruit hardness according to the investigation period was examined. The results are shown in Table 1. In addition, the relationship between the maximum water potential in the early morning of the following day and the measurement time of fruit hardness was examined. The results are shown in FIGS.

  As is clear from Table 1, a high relationship was observed between water potential and fruit hardness until the end of August. Therefore, for the extremely early-growth Wenzhou, the fruit hardness can be used for investigation of water stress until the end of August. As is clear from FIG. 6 and FIG. 7, the relationship between the maximum water potential in the early morning, which is an index of water stress, and the hardness of the fruit is determined after sunset in both the hand feel and the durometer measurement. The highest relationship is seen. That is, if the hardness of the fruit is examined after sunset, the maximum water potential in the next morning can be estimated.

  Then, the manufacturing method of the fruit model 12 which comprises the moisture stress measuring tool 10 of this embodiment is demonstrated. In early August, a model was made from a 43 mm-wide fruit of Wenzhou, and four kinds of fruit models with different hardnesses were produced using four kinds of commercially available silicones. For reference, a spherical fruit model having a diameter of 43 mm was also produced in the same manner. And the hardness of these fruit models was measured with the durometer. Specifically, the equatorial plane of the fruit model was measured with a durometer ESE type. The measurement results are shown in Table 2.

  The reason why the lateral diameter of 43 mm is adopted as the size of the fruit model 12 is that the lateral diameter of 43 mm is the most common appearance shape at the time when the fruit model 12 and the fruit are gripped.

  In addition, the hardness of the tangerine-shaped fruit model is plotted against the graph of the fruit hardness after sunset and the maximum water potential of the next morning investigated in another test. I examined whether it was true. The result is shown in FIG.

  As shown in Table 2, the variation in hardness is relatively small in both the tangerine fruit model and the spherical fruit model. In addition, as shown in FIG. 8, the citrus fruit model formed of silicone rubber having a hardness level A showed a maximum water potential in the vicinity of -1.3 to -1.6 Mpa. In the mandarin orange-shaped fruit model formed with silicone rubber having a hardness level B, the maximum water potential was around -0.8 to -1.0 Mpa. In the mandarin orange-shaped fruit model formed with silicone rubber having a hardness level C, the maximum water potential was around -0.3 to -0.4 Mpa.

  That is, the hardness of these three kinds of fruit models 12 is distributed in the fluctuation range of the actual fruit hardness. In addition, when the relationship between the hardness of the fruit after sunset and the maximum water potential in the next morning is applied, the fruit model 12 formed of silicone rubber having a hardness level A is in a state where a strong water stress is given to the fruit tree. It shows the hardness of the fruit, and the fruit model 12 formed of silicone rubber of hardness level B shows the hardness of the fruit in a state where water stress that generally requires watering is given to the fruit tree. The fruit model 12 formed of silicone rubber having a hardness level C indicates the hardness of the fruit in a state where there is almost no moisture stress in the fruit tree.

  And based on this result, the fruit model 12 formed with the silicone rubber of the hardness level A is converted into the high standard fruit model 16 of the hardness index level 2 and the fruit model 12 formed of the silicone rubber of the hardness level B. A standard fruit model 14 having a hardness index level 3 and a fruit model 12 formed of silicone rubber having a hardness level C were designated as a low standard fruit model 18 having a hardness index level 4.

  Subsequently, using the water stress measuring tool 10 of the present embodiment, the suitability of the water stress in the fruit tree was determined, and the quality of the fruit cultivated by the cultivation method for controlling the soil moisture was examined based on the determination result. This survey was conducted in six areas with different irrigation standards (see Table 3). In addition, each area is considered to be a gentle slope facing north, and its area is 36 square meters and the number of trees planted is 6.

  In the area A, an irrigation standard was set such that irrigation occurs when the fruit hardness is less than an index level of around 8 in the morning. In the area B, an irrigation standard was set such that irrigation occurs when the fruit hardness is less than the index level 3 at around 18:30 after sunset. In the area C, an irrigation standard was set such that irrigation was performed when the fruit hardness was less than an index level of about 4:30 pm after sunset. In the area D, an irrigation standard for irrigating when the index level was about 2 around 13:00 noon was set. In these areas A, B, C, and D, 50 liters were irrigated for each fruit tree when the irrigation standard was reached. In Zone E, irrigation was performed every 1-2 days without setting special irrigation standards. In Zone F, no special irrigation standards were set and left in the natural state. In areas A, B, C, and D, a breathable waterproof sheet (so-called mulch) was laid under the crown from July 30, 2007 to the end of harvest. In areas E and F, no mulch was used. The irrigation standards were checked three times after morning, noon, and sunset on a daily basis from August 2 to 2. When the standard was reached, irrigation was carried out by the drip irrigation facility. In addition, irrigation according to the irrigation standard was performed until September 1, and thereafter, irrigation was performed when the clear sky continued for three days. Specifically, on September 5th and 11th, 50 liters of water was irrigated for each fruit tree in all the multi-treatment areas (zones A, B, C, and D).

  Moreover, about the quality of the fruit, it investigated for the three fruit extract | collected from one fruit tree at intervals of 10 days. On September 21 and October 1, seven fruits collected from one fruit tree were investigated.

  Changes in the index level for each survey time are shown in FIGS. Moreover, transition of fruit quality is shown in FIGS. Furthermore, Table 4 shows the quality of the fruits examined on September 21, 2007.

  As is apparent from FIGS. 9 to 11, the hardness check after sunset has the largest difference due to the difference in area, and it is easy to catch the difference in moisture stress. Further, as is apparent from Table 4 and FIG. 12, in the multi-processing areas (areas A, B, C, and D), the sugar content at the time of harvest was 10.5 or more. In addition, since the drying was intense this year, the sugar content became 10 or more also in the area F. Further, as is apparent from Table 4 and FIG. 13, the citric acid was 1.0% in the area C as of September 21. The other multi-treatment areas (areas A, B, D) were about 0.2% higher than area C.

  As is clear from these results, it can be seen that high-quality fruits can be produced by determining the suitability of moisture stress in fruit trees using the moisture stress measuring device 10 of the present embodiment.

  As mentioned above, although one embodiment and some examples of the present invention have been described in detail, these are merely examples, and the present invention is not limited in any way by specific descriptions in such embodiments and examples. Is not to be interpreted.

  For example, the number of fruit models in the moisture stress measuring device may be two, or four or more. Moreover, the fruit model does not need to be connected by the connecting member.

  Furthermore, the connection member does not need to be disposed so as to penetrate each of the plurality of fruit models. For example, in each fruit model, an upper recess that opens upward and a lower recess that opens downward are formed, and one end of a rod-shaped connecting member is fitted into the lower recess of one fruit model. A plurality of fruit models may be connected by a connecting member by fitting the other end into the upper recess of the other fruit model. Or you may connect a some fruit model with the fishing line which penetrates a some fruit model. In this case, the connecting member is constituted by the fishing line. In addition, when connecting a some fruit model with a fishing line, you may extrapolate the tube made from a synthetic resin (for example, polyethylene) to the part exposed to the outside in a fishing line. Thereby, the distance between fruit models can be set to a suitable length.

  Furthermore, the hardness identifying means may display characters, symbols, etc. on the surface of the fruit model. Moreover, you may comprise a hardness identification means with the character, symbol, etc. which were displayed on the surface of the connection member. Furthermore, when a plurality of fruit models are connected to each other by a chain, a string, or the like with respect to a ring-shaped member for suspending a moisture stress measuring instrument on a wall or the like, the fruit model is used as a ring-shaped member. You may comprise a hardness identification means by making the length of the chain | strand for connecting, a string, etc. mutually differ.

  Moreover, in the said embodiment, the some fruit model 12 may be comprised by the two fruit models 12. FIG. For example, a combination of the standard fruit model 14 and the high standard fruit model 16 may be used, or a combination of the standard fruit model 14 and the low standard fruit model 18 may be used. The low standard fruit model 18 and the high standard fruit model 18 may be used. There may be 16 combinations.

  Furthermore, in the said embodiment, you may compare hardness using a suitable pincer. For example, when a person with weak force or a person with a disability compares hardness, or when more accurate hardness comparison is required, use a pinch that can be used easily and based on the reaction force You may compare hardness.

  Moreover, the fruit model which imitated the fruit may differ in the "simulated concrete shape" according to the method of touching the hardness of a fruit with a finger. For example, if a force is applied only in the lateral direction of the fruit and touched and compared with the fruit model, for example, a cylindrical fruit model having at least approximately the same outer diameter as the equatorial plane of the fruit, etc. Can also be adopted as a fruit model imitating fruit. In addition, since the fruit which a fruit model imitates is a fruit as a natural product cultivated, the magnitude | size and shape of a fruit model differ according to the kind, pattern, etc. of the fruit.

  Furthermore, even after the vacuole development period, the suitability of water stress may be determined by comparing the hardness. Also, because the fruit is green in the vacuole development period, when the fruit matures and its color becomes light green or yellowish, the vacuole development period has passed. I understand. Therefore, based on the color of the fruit, it may be determined whether or not the hardness comparison for determining the suitability of moisture stress should be performed.

  In addition, although not listed one by one, the present invention can be carried out in a mode to which various changes, modifications, improvements and the like are added based on the knowledge of those skilled in the art. It goes without saying that all are included in the scope of the present invention without departing from the spirit of the present invention.

The front view which shows the moisture stress measuring tool as one Embodiment of this invention. The graph which shows the correlation with the hardness felt with a hand, and the measurement result by a durometer. The graph which shows the change of the hardness of the fruit in one day. The graph which shows transition of the hardness of the fruit in Wenzhou very early growth under wet management. The graph which shows transition of the hardness of the fruit in early-growth Wenzhou under wet management. The graph which shows the relationship between the maximum water potential of the early morning of the next day, and the measurement time of the fruit hardness by durometer. The graph which shows the relationship between the maximum water potential of the early morning of the next day, and the measurement time of the hardness of the fruit by a hand touch. The graph which shows the positional relationship of the hardness and maximum potential of a mandarin-fruit model. The graph which shows transition of the index level measured in the morning. The graph which shows transition of the index level measured at noon. The graph which shows transition of the index level measured after sunset. The graph which shows transition of the sugar content of a fruit. The graph which shows transition of the citric acid of a fruit.

Explanation of symbols

10: Water stress measuring instrument, 12: Fruit model, 14: Irrigation standard model, 16: High standard fruit model, 18: Low standard fruit model, 20: Connection tube

Claims (8)

It is a moisture control cultivation method for citrus fruits that covers the surface of farmland with a breathable waterproof sheet and provides a irrigation system to control and cultivate soil moisture,
In the vacuole development stage, touch the hardness of the fruit with your fingers and compare the feel of the fruit with the fruit model using a synthetic resin-like fruit model that mimics the fruit. A moisture control cultivation method for citrus fruits, wherein the suitability of moisture stress is determined, and soil moisture is controlled based on the determination result.   The said fruit model prepares multiple types by mutually different hardness, The suitability of the water stress in a fruit tree is judged by comparing the hardness by the tactile sensation of these multiple types of fruit models and the said fruit. Citrus moisture control cultivation method.   The water control cultivation method of the citrus fruit of Claim 1 or 2 which judges the suitability of the water stress in the fruit tree based on the comparison of the hardness by the tactile sensation of the said fruit model and the said fruit after sunset.   It is composed of a combination of multiple types of fruit models that are formed of synthetic resin materials, imitating the fruits of the citrus vacuole development stage, and the hardness of these multiple types of fruit models. Is set to simulate the hardness that appears in the fruit according to the degree of water stress given to the fruit tree during cultivation of the fruit.   The plurality of fruit models include a reference fruit model simulating the hardness that appears in the fruit under a moderate water stress, and a hardness that appears in the fruit in a state where the water stress is stronger than the reference fruit model. The at least two of the high standard fruit model which imitated and the low standard fruit model which imitated the hardness which appears in the fruit in a state where water stress is weaker than the standard fruit model is included. Citrus moisture stress measuring instrument.   The citrus moisture stress measuring device according to claim 4 or 5, wherein hardness identifying means for identifying the hardness of the plurality of fruit models from the appearance is provided.   The citrus moisture stress measuring device according to claim 6, wherein the hardness identifying means is configured by coloring the plurality of fruit models in mutually different colors.   The citrus moisture stress measuring device according to any one of claims 4 to 7, wherein a connecting member for connecting the plurality of fruit models is provided.