日本寒地北海道的优质糯米育种

Breeding for High Quality Glutinous Rice in Hokkaido in Northern Japan

北海道糯米一直以来由于硬化性低而不易变硬,所以适合做糯米小豆饭和日式点心等。但与东北以南的品牌糯米相比,其精米蛋白含量(蛋白质)高,精米白度和捣年糕口感等较差。近年来为了扩大需求,还要求培育用于切块年糕、成型年糕以及适合米制点心的捣年糕硬化性高的品种。因此,对早期开发新品种进行了世代促进栽培及药物培养等,为提高选拔效率,从初期世代就开始对糙米和精米的白度、蛋白质以及和硬化性相关的糊化特性等用仪器进行了分析,并用少量糯米实测了硬化性;从中期世代开始进行了糯米小豆饭和捣年糕的品尝试验等,在推进改善其农艺性状的同时促进了品质改良。其结果是:近年来培育的糯米品种颗粒很大,穗孕期和开花期两个障碍型耐冷性都很强,提高了生产稳定性。进而,培育年份上,越是新品种蛋白质越低,与蛋白质呈负相关关系的精米白度就越高,而糯米小豆饭和捣年糕的口感也提高了。另一方面,关于捣年糕的硬化性,不仅培育出了传统的硬化性低的品种,而且培育出了以黏性品种为母本的硬化性高的两个新品种。但与东北以南的品牌糯米相比,捣年糕的口感和硬化性还不高,还需要进一步改良。

Glutinous rice produced in the coldest rice cultivation region of Hokkaido Japan has low hardening speed and is suitable for Japanese sweet and steamed glutinous rice called okowa.However,compared to the main branded glutinous varieties in the area south of Tohoku district,rice produced in Hokkaido has a high protein content,low whiteness of milled rice,and low eating quality of pounded rice cake.Moreover,recently in order to expand demands for Hokkaido rice,it’s required to develop a new variety suitable for sliced rice-cake,molded rice-cake and rice cracker while has high hardening speed of pounded rice-cake.In order to develop a new variety quickly,we used accelerated generation advancement and drug cultivation techniques.In addition,for efficient selection,we analyzed the whiteness of brown and milled rice,the protein content and gelatinization property which is related to hardening speed from early generations of breeding materials mechanically.We also measured hardening speed using a small amount of rice sample.We tested the eating quality of steamed glutinous rice and of pounded rice-cake from the intermediate generations.In this way,agronomic characters and quality were improved at the same time.We obtained newly bred varieties with larger grain size and higher cold tolerance at both the flowering and the booting stages,leading to higher stability for production.Compared to earlier generation,later generation varieties had a lower protein content,higher whiteness of milled rice,and higher eating qualities of steamed glutinous rice and pounded rice-cake.Moreover,a negative correlation was found between the protein content and the whiteness of milled rice.On the other hand,in addition to new rice varieties with low hardening speed,two new varieties with high hardening speed were developed.However,concerning eating quality and hardening speed of pounded rice cake,these new varieties were inferior to the top branded glutinous varieties in the area of south of Tohoku district,and need to be improved further.