Total soluble solid contents in fruit (fruit TSS), and nitrogen (N) and potassium (K) contents in leaf and fruit of ‘Shimizu-hakuto’ peach were analyzed in 23 orchards located in the south part of Okayama Prefecture during the seasons from 1997 to 1999. Significant negative correlations were obtained between fruit TSS and N contents in leaf, K contents in leaf, and N contents in fruit juice, where the correlation coefficients were −0.477, −0.677, and −0.616, respectively. The correlation coefficient between fruit TSS and leaf N contents was highest at 60 days after full bloom, and then decreased with the progression of growth season. On the other hand, the variation of correlation coefficients between fruit TSS and leaf K contents among growth seasons was small. The analysis of the relationship between annual changes of fruit TSS and nutritional status of peach trees revealed that fruit TSS increased in the trees where leaf or fruit juice N contents decreased than those in previous year.

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In foliar spray, as the solution dried up in short period, leaves can not absorb enough. We xamained water absorption through the intact leaves dipped in water. Amount of foliar absorption remarkably increased by dipping leaves in the solution as compared with spraying. Transpiration from whole and water absorption through apoplast of the intact leaves which were under water of the same plant were measured simultaneously for a whole day using salvia, cucumber and sweet potato plants. On fine day, transpiration preceded the absorption in the morning, and after the transpiration reached the maximum, followed by the absorption increase. In evening the both declined rapidly.

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To examine the effects of low temperatures on flowering of Lathyrus latifolius L. under long day conditions, various temperatures were applied to imbibed seeds or seedlings for various duration and then grown in a greenhouse kept above 15°C and under 16 h day length. Exposure of imbibed seeds to low temperature of 1°C for 30 days had no effect on flowering in ‘Pink Pearl’, ‘Red Pearl’ and ‘White Pearl’. When seedlings of ‘Pink Pearl’ were grown in a greenhouse kept at 15–25°C for 6 months then exposed to temperatures of 1, 5, 10 and 15°C for 8 weeks, days to flowering and nodes to the first flower were reduced and number of florets of the first inflorescence was increased in plants raised from seedlings exposed to 1 or 5°C. Subjecting seedlings to 5°C for more than 8 weeks was necessary to promote flowering. A growing period for more than 110 days was needed to respond to the low temperature treatment. When plants were exposed to natural low temperatures for 0, 30, 60, 90 days and then grown under four photoperiods (10, 12, 14, 16 h) in the glasshouse kept above 15°C, the flowering percentage did not change under a day length of 10 or 12 h irrespective of the length of exposure to natural low temperature. This finding indicates that the qualitative long day requirement for flowering remains unaltered even in plants that received natural low temperatures for 3 months.

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The volumetric water content (VWC) in the branches and trunks of satsuma mandarin (Citrus unshiu Marcow.) was measured using a stainless nail a sensor probe and a portable time domain reflectometry (TDR) soil moisture meter. Two treatments were set up. In one treatment, water stress was applied between May 20 and June 24, then irrigation was conducted twice weekly until July 28. The other treatment was a reverse schedule of irrigation and water stress. Since July 28, water stress was started in both treatments. The water stress was initiated by covering the soil surface with a vapor-permeable sheet. VWC in the branches and trunks changed with the seasons regardless of which treatment had been applied. The VWC increased from the beginning to mid-July and stabilized with little variance until mid-September, when it decreased. The VWC of the branches and trunks changed in accordance with the soil moisture conditions, which were influenced by irrigation, precipitation, and mulching. Variance of measurements is smaller in the trunk than in the branches. The decrease in VWC appeared in mid-July, about three weeks later than the day when the soil was covered with a vapor-permeable sheet. Until harvesting period, the VWC in the branches and trunks in trees with water stress from June 24 to July 28 was lower than that in trees with water stress from May 20 to June 24. Changes in the Brix of the juice were attributed to seasonal differences in the VWC caused by two types of treatment.

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Potted trees of 4-year-old ‘Gold Nijisseiki’ were used to compare two different training methods. The effects of 2-scaffolds and 5 or 6-scaffolds for young trees on the dry matter partitioning were studied. In addition, the trees were treated with ¹³C as a tracer in June and August to investigate how differences in training methods affected the translocation of photosynthates. Shoot growth was vigorous in the 2-scaffold trees. In contrast, multiple scaffold trees showed suppressed shoot growth, elongated older wood, and a large fruit number. Dry matter distribution ratios in different organs were compared. The ratio was high in shoots and shoot leaves of the 2-scaffold trees and in older wood and fruit of the multiple-scaffold trees. The distribution ratios of ¹³C in different organs were compared. The ratio was higher in fruit, older wood, trunks, and fine roots of multiple-scaffold trees than in those of the 2-scaffold trees; it was higher in shoots of 2-scaffold trees than in those of the multiple-scaffold trees. Consequently the multiple-scaffold training method was judged to suppress shoot growth, expand fast in the canopy of young trees, and promote an early increase in yield.

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A simple new estimation method for water status in satsuma mandarin (Citrus unshiu Marcow.) was developed, expecting to improve irrigation in the summer and early autumn seasons and increase fruit quality. As a patch test, a “Water Stress Indicator” stuck on the abaxial side of the leaf changed color depends on the water status of the satsuma mandarin tree. The indicator is based on the fact that Cobalt(II) chloride changes its color by hydration reaction; if there is sufficient moisture, the light blue turns to a light red. To determine the appropriate condition of this indicator usage, the relationship between the diurnal change of transpiration and the leaf water potential (LWP) before sunrise was investigated. There was a clear difference in the transpiration rate of satsuma mandarin leaves around midday on a comparison of satsuma mandarin trees under various water statuses. If the transpiration rate was above the cut off (3 μg·cm⁻²·s⁻¹), LWP should be −0.8 MPa or more. Together with these results, the indicator should be stuck on the abaxial side of a leaf that receives sufficient sunshine around noon. Under this condition, if the indicator color turns light red within 5 min, the satsuma mandarin tree tested is not under water stress. The "Water Stress Indicator" would facilitate visual estimation of the water state from summer to early autumn.

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This study investigated the cultivation technique for high yield with high profit in mother fern green asparagus (Asparagus officinalis L.) cultivation. Effects of standing time and size of mother fern on the yield and size of spears were investigated. Spear emergence was temporarily suppressed after the beginning of mother fern establishment. When the beginning of mother fern establishment was later, the spear yields in spring and summer became higher and lower, respectively. The highest yield throughout the whole harvesting period was given when the mother fern was established from 50 to 60 days after spear harvesting. The optimal diameter of mother fern for higher yields in summer and next spring, for total spears and for a higher rate of large (L) class spears ranged from 10 to 14 mm. As the price of spring spears is higher than that of summer spears, the highest profit was expected when the mother fern was established between 50 and 60 days after spear harvesting.

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The effects of NAA and ethychlozate on flowering ability and the concentration of endogenous nutritional elements of summer shoots in satsuma mandarin grown in an early heating plastic house and started heating in November were compared. Regarding the flowering ability, it was evident that the physiological flower bud differentiation proceeded at a more rapid pace and was completed earlier and that the number of flowers was greater with NAA treatment. In NAA treatment, the shoots and leaves contained more starch and less nitrogen. These findings suggest that plants treated with NAA will have better floral evocation and thus bear more flowers than those treated with ethychlozate.

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To clarify the correlation between the occurrence of internal browning (IB) in Raphanus root and the thermal condition, especially, during the later growth period, a logit model was established, using the severity of IB in plant grown under different covering materials along with air and/or soil temperature data. Analytical results demonstrated that independent variables of 35°C for maximum air temperature or 29°C for maximum soil temperature were the most adaptable. The percentages of correct predictions using those models were high, ranging from 80% to 90%. These observations strongly suggest that the severity of IB is closely correlated with thermal conditions during the later growth period, and could be controlled by changing these conditions.

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It is necessary to clarify the dormancy period of Budousanshou (Zanthoxylum piperitum (L.) DC. f. inerme Makino), Japanese pepper tree, to prevent unexpected bud break caused by defoliation in autumn as well as to consider early marketing from a heated greenhouse culture in order to achieve higher market price. The dormancy period of Budousanshou was investigated by the stem cutting method using stems picked regularly after October in Wakayama Prefecture. The breaking dormancy period was investigated by heating potted plants after January in Nagasaki Prefecture. It was observed that internal dormancy was deeper at the end of November when average air and soil temperature had decreased below 10°C and 15°C, respectively, and yellowing of the leaves occurred during the same period. Furthermore, breaking of the dormancy occurred at the end of January after the accumulated time below 5°C exceeded 1000 hrs and Budousanshou sprouted within 10 days with heating. Therefore, this finding can be used as a rough estimate to start heating greenhouse for early marketing.

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Involvement of phytohormones in the formation of double pistils in sweet cherry (Prunus avium L.) was investigated. 1) ‘Satohnishiki’ spurs were sprayed with naphthaleneacetic acid (NAA), abscisic acid (ABA), gibberellin A₃ (GA₃), benzyleadenine (BA) and ethephon at 100 ppm. BA and ethephon treatments increased the percentage of flowers with double pistils. However, the frequency of double pistils was low in NAA, ABA and GA₃ treatments. 2) Spurs of ‘Satohnishiki’ and ‘Napoleon’ were sprayed with 50 and 200 ppm BA. BA hastened the progression of flower differentiation and increased the occurrence of double pistils. 3) ‘Satohnishiki’ spurs were sprayed with 100 and 200 ppm ethephon. Ethephon also increased the frequency of double pistils, but delayed flower differentiation. 4) Ethylene production by spurs of the trees grown in sunlit growth chambers controlled at 20°C, 30°C, 35°C, increased with the temperature. These findings showed that BA and ethephon induce the formation of double pistils in sweet cherry. Since ethephon delayed the progression of flower differentiation similar to that due to high temperature and high temperature increased ethylene production by spurs, it is suggested that ethylene could be involved in the formation of double pistils induced by high temperature. However, BA accelerated flower differentiation in contrast to high temperature, indicating that the mechanism of pistil doubling induced by BA differs from that induced by high temperature.

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The effects of DIF (difference between day and night temperature), TD (short time temperature drop) and TR (short time temperature rising) on the growth of Delphinium grandiflorum L. cv. ‘Blue Mirror’ were investigated. Minus DIF (15°C and 25°C during the light and dark period, respectively) decreased the plant height by 42% to 49% compared to that of plants treated with plus DIF (25°C and 15°C during the light and dark period, respectively). TD down to 10°C for 4 hours started 2 hours before the end of the dark, did not influence the plant height. On the other hand, TR up to 30°C for 4 hours at the beginning of the dark period, decreased the height by 22% to 33% compared to that of +DIF. Both length and width of stem pith cells in the plants treated with −DIF, were decreased by about 20% compared to those of +DIF. Plants −DIF showed a decrease in the relative number of pith cells in the vertical direction by 26% compared to that of plants +DIF, although the number in the horizontal direction were decreased by only 5%. Endogenous gibberellins, GA₉ and GA₂₄, were identified in the shoot of D. grandiflorum. The concentration of GA₂₄ was lower in −DIF than in +DIF, indicating that DIF regulated the stem elongation through biosynthesis of gibberellin.

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Watermelon fruits were enclosed within 20 cm cube boxes to mechanically restrict the enlargement and changes in sugar concentration and cell size were investigated. Covering with a cube box from 15 to 45 days after pollination significantly restricted fruit enlargement of the watermelon. This mechanical restriction of fruit enlargement resulted in decreased sucrose accumulation at the central portion of the fruits, in contrast to increased accumulation of this element at the outer portion. Cell size in the fruits also varied according to the mechanical restriction. At the central portion of the fruits, a larger number of small cells derived from vascular bundles was detected in the restricted fruits. Conversely, meristematic cells in the outer portion increased in size due to the mechanical restriction.

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Effect of sucrose concentration on flower qualities and changes in sugar concentrations during bud development in carnations (Dianthus caryophyllus L. ‘Nora’) were investigated. Bud cut carnation flowers were treated with sucrose solutions ranging from 0% to 17% at 23°C. Sucrose concentrations had no influence on the number of days from bud to full bloom. Sucrose at high concentrations was effective in increasing the flower diameter and improved petal color pigmentation. In the calyx, leaf and stem of intact carnations, concentrations of pinitol, sucrose, glucose and fructose remained almost constant during bud development. In petals of intact carnations, concentrations of fructose and glucose increased markedly with bud development. In all organs of bud cut carnations treated with 0% sucrose, concentrations of these sugars, except for pinitol, decreased markedly and remained very low during the experimental period. Decrease in the sugar concentrations in all organs was suppressed by 5% sucrose treatment, although the concentrations were relatively low levels compared with those of the intact carnation. These findings suggest that sucrose increases sugar concentrations in petals, which may improve flower size and petal color pigmentation of bud cut carnations.

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The effect of cold treatment on sugar concentration, sweetness and decay in Ipomoea roots was studied. Storage temperature were 3, 5, 10 and 13°C. Sugar concentrations, with the exception of maltose, varied significantly with changes in storage temperatures from 3 to 13°C. The sucrose concentrations in roots stored at 3 to 5°C increased more rapidly than that at 10 to 13°C. In contrast to the change in sucrose concentration, glucose and fructose concentrations increased slightly during storage at 3 to 5°C, whereas these concentrations increased significantly during storage at 10 to 13°C. Consequently, the sweetness calculated from these sugar concentrations was higher at 5 or 10°C storage than at other temperatures. However, roots stored at 5°C exhibited decay as a result of chilling injury. These observations suggest that storage at 10°C is more effective for increasing sweetness in Ipomoea roots.

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We mixed the activated carbon, which effectively adsorbs the allelochemicals of asparagus (Asparagus officinalis L.), into the substrate during the seedling stage, and investigated its effects on the growth of asparagus. As a result, the mixture of the activated carbon with the substrate led to the production of asparagus seedlings with a high quality while reducing allelopathy. We also investigated the effects of activated carbon mixed into the substrate on the growth of 30 species of eight different families, and found that the growth of tomato (Lycopersicon esculentum Mill.), prairie gentian (Eustoma grandiflorum (Raf.) Shinn.), lettuce (Lactuca sativa L. Capitata Group.), cucumber (Cucumis sativus L.), cabbage (Brassica oleracea L. Capitata Group), broccoli (Brassica oleracea L. Italica Group) and asparagus was increased by mixing the substrate with activated carbon compared to growth in those species without activated carbon. The mixture of activated carbon into the substrate during the seedling stage would be useful for promoting the growth of certain plants, in which allelochemical activity is reported to be high.

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