日本寒冷地带北海道抑制粳稻生成白未熟粒的栽培法

Cultivation Techniques of Nonglutinous Rice for Suppressing the Occurrence of White Immature Kernel in Cold Region of Hokkaido in Japan

白未熟粒的多发会使整粒率下降,降低检查等级,因此急需抑制其发生。白未熟粒中,乳白粒和基部未熟粒的发生率存在品种间差异。切除止叶减少光合作用,增肥导致每平方米稻谷数量的增加,疏植和育苗时高温引起早期异常抽穗所致的齐穗不良,以及收割时期的延迟等会造成白未熟粒的增多。此外倒伏还会导致青未熟粒、白未熟粒增多。在初期生长良好的情况下,从分蘖期开始的深水灌溉抑制了过剩的分蘖产生,增加了粒重和糙米产量,使糙米品质得以提高。由于成熟期的土壤过于干燥,因腹白粒产生引起的品质降低和千粒重减少会导致减产。从抽穗期到齐穗期10天后的茎叶到稻谷的每粒稻谷非结构性碳水化合物(NSC)流转量,以及粗糙米产量减去同一流转量的每粒稻谷NSC增加量越多,这些白未熟粒的产生就越少。为避免白未熟粒的多发,必须使施肥量、种植密度、育苗温室的温度管理、移植时期、成熟期的土壤水分和收割时期合理化,促进初期生长,用深水抑制过剩的分蘖。通过改善以上的栽培方法,以及1990年代中期后在共同干燥调制储藏设施中使用色选机选别糙米,北海道的一等米比例超过了日本全国的平均水平。

The increase of white immature kernel decrease the percentage of whole grain and lower the inspection grade.In the occurrence rate of white immature kernel,especially in those of milky white rice kernel and in immature base rice kernel,differences among varieties were found.Number of white immature kernel were increased by decreasing quantity of photosynthesis treated with defoliation of flag leaf.Poor panicle uniformity results from abnormal heading in early stage caused by high temperature in sparse planting and seedling raising,and delay in harvesting time etc.,All of this will cause the increase of white immature grains.In addition,lodging will lead to the increase of green and white immature grains.Under the condition of good growth at the initial stage,deep water irrigation from tillering stage inhibited the production of excess tillers,increased grain weight and brown rice yield,and improved the quality of brown rice.Because the soil in mature stage is too dry,the decrease of quality and 1000 grain weight caused by the production of abdominal white grains will lead to the decrease of yield.Number of these white immature kernels were decreased by increasing the amount of non-structural carbohydrates(NSC)translocated from rice shoot to rough rice(per rough rice)during the period from heading to 10 days after full heading time and by increasing the amount of NSC(per rough rice)that is subtracting grain yield of crude brown rice from its translocated NSC.In order to decrease the number of white immature kernels,the amount of fertilizer application,planting density,temperature in rearing seedling house,time of transplanting,soil moisture during grain filling period and time of harvesting are needed to be in proper,and increasing initial growth are necessary.The large numbers of tiller is controlled by deep-flood irrigation from initial growth.Addition to those improved cultivation method,using color-sorting machine in the common drying and storage facilities after the mid-1990 s,the proportion of first-class rice in Hokkaido exceeded the national average level in Japan.