Studies in adaptation of new Japanese pear cultivars to major pear growing area

研究了作者培育的日本梨新品种‘秋梨’、‘梨树’和‘新梨’在梨主产区的适应性。3个品种的砧木种类对梨树生长和果实品质无明显影响。测定了不同品种果实的贮藏潜力和乙烯释放量。‘新津’表现出较高的乙烯释放量和较低的贮藏潜力。‘秋梨’和‘嘴薯’果实乙烯释放量低，具有较高的贮藏潜力，‘秋梨’果实在果实成熟前一直保持较高的淀粉含量，进入成熟期蔗糖含量最高。这3个品种在日本梨种植区福岛、千叶、长野和鸟取县的果实品质表现优异，但在这些地区的‘秋葵’果实中发现了水核病。‘秋葵’果实的水核病发生率在GA处理后增加，而在夏收时则受到抑制。‘秋葵’夏梢修剪对果实品质无明显影响，夏播制度似乎是防治秋葵水芯病的实用方法之一。减轻症状的机理可能是通过抑制果实糖分超载来实现的。

Adaptability to the major pear growing area of the new Japanese pear cultivars 'Akibae', 'Zuishu' and 'Shinzyu' which were breaded by the authors were investigated.Tree growth and fruit quality was not affected by the rootstocks species when these three cultivars were grown on P. betulaefolia and P. callerayana rootstocks. The storage potential and ethylene evolution of fruit of the cultivars were determined. 'Shinzyu' showed higher ethylene evolution and low storage potential. In contrast 'Akibae' and 'Zuishu' had high storage potential due to their low ethylene evolution.'Akibae' fruit kept high starch content until just before maturation, then it showed the highest sucrose contents than the other Japanese pear cultivars when fruit reached the mature stage. These three cultivars showed excellent fruit quality on the Fukushima, Chiba, Nagano and Tottori where the pear growing area in Japan, however, Watercore disease was detected in 'Akibae' fruit on these area.Watercore incidence in 'Akibae' fruit was increased by GA treatment and prevented by summer running. The fruit quality of 'Akibae' did not affected when new shoot was pruned in summer, thus summer running system seemed to be one of the practical method to prevent the watercore incidence. The mechanism of the decrease of the symptom may occurred by the inhibition of over load of sugar to the fruits.