Study of yield loss and its mechanisms caused by grain shattering habit of crops.

碎粒习性是植物的基本性状之一，因为野生植物对种子的传播很重要，但对粮食作物来说，碎粒习性会造成收获前的产量损失。近年来，日本旱地退耕还田的大豆和荞麦种植面积有所增加，但由于收获阶段的碎粒习性，大豆和荞麦的产量损失严重。因此，目前的研究证明了产量损失在种植者的田间，并从品种变异和生长条件方面探讨了产量损失的机理。在本研究中，粉碎习惯造成的产量损失在品种、年份和地点之间是不同的，造成产量损失的原因是多方面的。例如，由于与水稻等其他作物的收获过程竞争，种植者失去了充足的收获时间，大豆田的粮食产量下降了20%至30%，…超过50%台风使荞麦的粮食产量减少了很多。收获前台风落下的籽粒可以作为下一次耕作的种子，通过耕作进行杂草控制。荞麦的落粒习性是由细梗引起的，花梗直径与籽粒大小存在遗传相关，因此重粒型品种比小粒型品种表现出较强的抗落粒性。由于籽粒成熟期籽粒品质变化较大，建议对荞麦进行提早收割，以改变籽粒品质，防止破碎造成严重损失。在大豆上，没有观察到碎粒习性与其他形态性状之间的明显关系。然而，种植者认为，田间生育期的差异给他们决定收获期带来了困难，收获期的误判导致了产量和籽粒品质的下降。田间生育期的差异是由土壤条件的变化、路灯的照度等多种原因造成的。田间生育期差异的空间分析表明，大豆生育期差异在田间随机发生，随着大豆成熟度的增加，差异逐渐减小。路灯的光质对大豆植株生长有影响，但蓝绿光和卤素块对植株生长延缓的影响较小。较少

Grain shattering habit is one of elemental traits on plants because of the importance on wild plants for the seed dispersal, but on grain crops it causes the yield loss before harvest. Recently, the cultivation area of soybean and buckwheat is increasing in the upland filed converted from paddy in Japan, but these crops are suggested to show severe yield loss caused by the grain shattering habit at the harvesting stage. Thus, current study demonstrated the yield loss at the grower's field, and the mechanisms of the yield loss were investigated on the variation of cultivars, and the growing conditions.In this study, the amount of yield loss caused by the shattering habit was various among cultivars, years and locations, and severe damage on yield was observed by several reasons. For example, 20 to 30% of grain yield was dropped in soybean field because growers lose the adequate harvesting time due to the competition with the harvest process of other crop such as rice, and more than 50% … More of grain yield of buckwheat was blown off by typhoon. The grains shed by typhoon before harvesting was available as the seed for the next cultivation under weed control by plowing. The grain shattering habit of buckwheat was caused from thin pedicels, and the diameter of pedicel was genetically correlated with the size of seed grain, thus the cultivars of heavy grain type showed resistance on the shattering compared to the cultivars of small grain type. To prevent from severe loss by shattering, the early harvesting on buckwheat was suggested to change the grain quality, because the grain quality was drastically changed at the grain ripening period. On soybean, the clear relationship between the grain shattering habit and other morphological traits was not observed. However, growers suggested that the difference of the growth stage in a field embarrassed them to decide the harvesting time, and the misjudgment of harvesting time caused the decrease of the yield and the grain quality. The difference of the growth stage in a filed was caused by several reasons such as the variation of soil conditions, and the illumination of streetlight. The spatial analysis on the difference of the growth stage in a filed demonstrated the difference of growth stage occurred randomly in the field and became small gradually as soybean maturated. The light quality of a streetlight influenced the plant growth of soybean due to the short day plant, but blue-green light and halogen lump showed smaller effect on the delay of plant growth. Less