To facilitate efficient breeding of table grape (Vitis spp.) cultivars with cracking resistance, we estimated the proportion of offspring with cracking resistance in a cross using data from 1373 individuals in 46 families. To estimate the proportions, we conducted logistic regression analyses using the mid-parental values (MPs) of cracking, flesh texture, and berry weight, and type of cross (interspecific hybrid × interspecific hybrid, interspecific hybrid × Vitis vinifera, and V. vinifera × V. vinifera) as explanatory variables. The proportion of offspring with cracking resistance in a cross decreased as MP of cracking increased, and as MP of flesh texture (from 0 = easy to masticate to 2 = difficult to masticate) decreased. MP of berry weight and type of cross were not effective as explanatory variables. Multiple logistic regression revealed that the most accurate model used MPs of cracking and flesh texture. The proportions of offspring in a cross with cracking resistance in which MP of cracking = 0 were estimated to be 52％ when MP of flesh texture = 0 and 91％ when MP of flesh texture = 2.0.

Chestnut trees in a new orchard, which have been transplanted from mountain hills and rice fields, are showing an increased number of freezing injuries. A combination of high ridge cultivation and black sheet mulching has become popular to reduce freezing injuries. In this study, we investigated the effects of soil hardness and microclimate around trees on the freezing temperature of shoots. We also studied factors responsible for reducing freezing injuries when high ridge cultivation and black sheet mulching were used. Soil hardness increased with depth on the flat ridge, while no such change was noted on the high ridge. Tree vigor on the high ridge was stronger than that of trees on the normal flat ridge. Regardless of the surface color of sheet mulching, it reduced the soil moisture content in the high ridge more than the soil in the non-mulched high and flat ridge. However no effect of any treatments were observed on the water content of shoots from February to April. The freezing temperature of the current shoot buds, in mid-February, was decreased on black mulching, but did not decrease on white mulching compared with the normal flat ridge. On the normal flat ridge, 25％ of trees died due to freezing injuries whereas no trees died on the high ridge, regardless of mulching. These results indicate that the popular solution to freezing injuries ameliorated physical conditions of the soil and kept it dryer than with other treatments. Consequently, high ridge cultivation and black mulching ensure a higher freezing tolerance than the conventional flat ridge.

In Japan, seedless grapes are obtained by applications of plant growth regulators such as gibberellic acid (GA₃) and 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU). To analyze the effect of these chemicals on the palatability of the texture of unpeeled ‘Shine Muscat’ grape berries in the mature stage, we treated plants with GA₃ plus CPPU on 1 day after full bloom and GA₃ at 10–12 days after full bloom (GA₃ 10DAFB). Then, we investigated the rheological properties and plant cell wall components. For texture analysis, mechanical properties were examined using a puncture test, and the peeling ability as a skin property was determined a tensile test. To assay cell wall components, berries were divided into three parts (central part of mesocarp, pericarp around skin, and skin). CPPU treatment of more than 5 ppm at full bloom led to inferior mechanical properties of berries. Furthermore, CPPU treatment of more than 5 ppm at full bloom increased cellulose contents of the skin and pericarp around the skin. GA₃ treatment increased berry firmness and strengthened adhesive forces between the skin and pulp. Simultaneously, uronic acid contents in the 0.05 N sodium carbonate solution-soluble fraction and total sugar contents in the 4 M KOH soluble fraction of the pericarp around the skin on GA₃ treatment were higher than those of the control. Therefore, the increase of cell wall components by GA₃ treatment made the berry texture firm and strengthened adhesive forces between the skin and pulp. These results suggest that each plant growth regulator affects the cell wall components of grape berries and varies their texture.

The flowers of spring-harvest cropping types of Eustoma occasionally exhibit nonuniformly colored petals. In the center petals of such flowers, pale greenish areas remain after flower opening. In this study, the effects of cultivation at high ambient temperatures (27°C) at the presumed flower-bud differentiation stage on the percentage of flowers with nonuniformly colored petals was investigated. The daily mean temperature in a greenhouse in Ibaraki Prefecture was less than 19°C from January 7 to February 18 (period of high-temperature treatment). The percentage of terminal flowers exhibiting nonuniform coloration was lower in plants cultivated at high ambient temperatures for 7 days starting from January 14, 21, and February 4, and for 14 days starting from January 7, 14, 21, 28, and February 4 compared with low-temperature treatment (controls). Compared with the controls, the percentage of lateral flowers with nonuniform coloration was lower in plants subjected to high ambient temperatures for 7 days starting from February 4 and for 14 days starting from January 28 and February 4. Similarly, fewer petals, stamens, and pistils tended to be produced at high ambient temperatures compared with the controls. In addition, numbers of petals, stamens, and pistils of terminal and lateral flowers with nonuniformly colored petals were significantly higher than those of normal flowers. The results showed that the petal number increased when plants were grown at low daily mean temperatures. Under these conditions, the developmental stage of inner petals may differ markedly from that of the outer petals, producing nonuniformly colored flowers. Increasing ambient temperatures during flower initiation and development is thus an effective means to reduce the production of nonuniformly colored flowers.

To clarify the inhibitory effect of high temperatures under natural light conditions during intermittent low-temperature storage (ILTS) for flower induction in June-bearing strawberries, high temperature treatments were conducted before or at 3 specified times of low-temperature storage for 3 days (15°C in dark). Among the three cultivars that exhibited different flowering behaviors on forcing culture, ‘Sachinoka’ was found to be the most sensitive to high temperatures, followed by ‘Tochiotome’ and ‘Sanukihime’. The effect of ILTS was the lowest on ‘Sachinoka’ when the daily average temperature was above 26°C under natural light conditions. However, there was only a minor inhibitory effect on ‘Sanukihime’ and ‘Tochiotome’, even when the temperature was high. In ‘Sachinoka’ and ‘Sanukihime’, the effect of ILTS tended to decrease by minor differences between the day and night temperatures when the mean temperature was 28°C. Additionally, the efficiency of ILTS did not decrease after encountering high-temperature conditions for 3 days.

In recent years, physiological disorders of crops caused by compost with residual clopyralid, a growth regulator herbicide registered for use in feed-exporting countries, has become a problem in Japanese agriculture. Thus, we compared the influence of clopyralid on the dry weight and morphology of aboveground parts in major crops of 23 plant species in 13 families according to the soil concentrations. We considered the characteristic symptoms by focusing on leaf shape. No effect of clopyralid on growth was observed in Welsh onion, oat, barley, spinach mustard, buckwheat, spinach, or sesame. However, clopyralid resulted in physiological growth disorders such as decreasing dry weight and/or abnormal morphology of aboveground parts in 16 plant species in seven families, including Fabaceae, Solanaceae, and Asteraceae. In particular, rugose leaves were observed in 13 plant species belonging to Fabaceae, Solanaceae, Campanulaceae, Asteraceae, and Apiaceae regardless of the leaf shape. These crops exhibited rolling up of the leaf margin, cupping, and curling up of the serrations before any apparent rugose leaves, and these are considered to be the initial physiological disorders of rugose leaves. These initial physiological disorders may depend on the shape of the leaf margin, such as having or not having serrations or lobes, rather than the shape of the leaf blade. Therefore, we suggest that observing the shape of the leaf margin could be used to determine any effect of clopyralid on crops belonging to families with high sensitivity to clopyralid, such as Fabaceae, Solanaceae, and Asteraceae.

The direct and indirect effects of light conditions on the development of the red flesh of ‘Kurenainoyume’ apples were examined in order to better understand the reasons for color variations as well as to develop management technologies to improve the flesh color. The amount of anthocyanin in the flesh was significantly correlated with the amount of anthocyanin in the skin, and anthocyanin in the flesh nearest the skin rose with increasing anthocyanin in the skin. LED blue light (450–470 nm) induced anthocyanin accumulation in the flesh of the fruit on the tree, as well as in the detached fruit. Blue light (450–470 nm) was highly effective in stimulating anthocyanin accumulation in sliced flesh, which had been irradiated directly. On the other hand, defoliation and ringing on the fruiting branch before anthocyanin accumulation significantly decreased the amount of anthocyanin in the flesh of bagged as well as non-bagged fruit. These results suggest that anthocyanin accumulation deep in the flesh of the fruit does not depend on light irradiation, but depends instead on photoassimilates. The results also showed that light conditions directly affect red coloration in the flesh near the skin, and indirectly affect anthocyanin accumulation in flesh at deeper positions within ‘Kurenainoyume’ apple fruit.

We investigated the effects of light, darkness, and temperature during storage assuming transportation on flower wilting and the flowering period of potted carnation (Dianthus caryophyllus L.). In the two cultivars ‘Grand Rouge’ and ‘Mahalo’, the flowering period was shortened by more than 2 days and the rate of flower wilting after 7 days was increased to 30 percent under the dark condition at 20°C compared with the light condition (PPFD; 110–214 μmol・m^–2・sec^–1・12 hours). Ethylene production was observed in the wilted flowers of ‘Mahalo’. In the two cultivars, treatment with 1-methylcyclopropene (1-MCP) at 1000 ppb for 12 hours extended the flowering period by more than 1 day and reduced the rate of flower wilting after 7 days by more than 30 percent under the dark condition at 20°C compared with the control. The sugar (sucrose, glucose, and fructose) contents in the leaf of ‘Grand Rouge’ stored for 16 days in the dark at 10°C was 1.75 mg・g^–1 FW, which was more than twice as high as at 20°C. In the two cultivars, the flowering period of the plants stored at 10°C was more than 2 days longer than that of those stored at 20°C, and flower wilting was not observed even after 14 days in the dark. In addition, the flower color of plants stored at 10°C for 14 days was almost the same as that before storage.

Bunching onion (Allium fistulosum L.) is a green vernalization-type plant. Cold treatment of plants that reach the mature phase induces flower bud formation, and subsequent high-temperature and long-day conditions lead to bolting. Because bolting reduces the commercial value of bunching onions, plants should be grown large enough to harvest before bolting. We sowed seeds of two spring-harvest cultivars of Kujo bunching onions (‘Kujofuto’ and ‘Haru-Anjo’) and a year-round-harvest cultivar (‘Super-Anjo’) between early August and mid-October and studied the effects of the growth stage during cold exposure in the field. Cold exposure of plants that did not reach the mature phase because of later sowing reduced the rate of bolting and delayed bolting progress of ‘Kujofuto’, but only delayed bolting progress of ‘Super-Anjo. We evaluated the timing of 50% bolting, when commercial value loss becomes prominent, and found that ‘Super-Anjo’ is an earlier bolting cultivar than ‘Kujofuto’. ‘Haru-Anjo’ is a later bolting cultivar; because of its slower bolting progress, most plants can be harvested before bolting, even when bolting has begun, and so there is a reduced risk of losing commercial value by bolting. All three cultivars have different genotypes regarding the speed of flower-bud growth, and each property prominently appears when not reaching the mature phase. Because a later-bolting genotype in ‘Haru-Anjo’ also appears even when not reaching the mature phase, we can select them to further reduce the bolting risk.

The effects of light irradiation on the surface blushing and anthocyanin content of postharvest Japanese apricot ‘Nanko’ fruit were investigated. Ultraviolet-B (UV-B) irradiation beyond 48 h resulted in surface blushing and increased the anthocyanin content in the flesh with skin, although the blushing was mottled. On simultaneously irradiating with red and UV-B light, there was bright surface blushing and a significantly higher anthocyanin content than in the case of only UV-B irradiation. The effect of simultaneous irradiation with UV-B and red light on the surface blushing and anthocyanin content was influenced by maturity, and the mature green and fully ripe fruit contained less anthocyanin than those of intermediate maturity. These results suggest that the surface blushing and anthocyanin content are associated with UV-B and red light and are influenced by the maturity of postharvest Japanese apricot ‘Nanko’ fruit.

Maintenance of green peel is desirable during storage and marketing of sudachi (Citrus sudachi Hort. ex Shirai) fruit. This study investigated the potential of edible coatings and 1-methylcyclopropene (1-MCP) treatment in extending the postharvest life during storage at 10, 15, and 20°C. Edible coatings were applied on freshly harvested green sudachi fruit either as a layer by layer (LBL), which involved alternate deposition of chitosan and alginate, or as an ion complex (IC) coating, which involved one-time deposition of a chitosan and alginate mixture. Storage at 10°C maintained the green peel color for up to 15 d with no significant differences among the treatments. At 15 and 20°C, the edible coatings significantly lowered ethylene production and respiration rates, and noticeably maintained green peel color for up to 19 d when applied as tri-layer IC, and 15 d when applied as tri-layer LBL. In addition, tri-layer IC coatings during storage at 15°C appeared to be more effective as they further extended the green peel stage to 21 d compared with 7 and 11 d for mono- and bilayer coatings, respectively. By contrast, 1-MCP treatment failed to inhibit peel yellowing, but instead stimulated fruit respiration and ethylene production. From these results, it is evident that edible coatings may provide a promising postharvest method to extend the postharvest life and preserve the quality of sudachi fruit.

‘Murasakizukin 4 gou’ was selected from the backcross progeny derived from a cross between the nonrecurrent parent ‘Tamadaikoku’ and recurrent parent ‘Shintanbaguro’. ‘Brown bloth symptom’, which is a major problem in ‘Shintanbaguro’, is not observed in ‘Murasakizukin 4 gou’ as it is resistance to the A strain of the soybean mosaic virus. Compared with ‘Shintanbaguro’, ‘Murasakizukin 4 gou’ has the same or slightly earlier flowering and harvesting times, a longer main stem, and greater pod yield per plant. Furthermore, the sucrose and amino acid contents in the seeds of ‘Murasakizukin 4 gou’ were higher than those of ‘Shintanbaguro’, and the eating quality evaluation of ‘Murasakizukin 4 gou’ was higher than that of ‘Shintanbaguro’.