日本寒冷地带北海道粳稻米粒外观品质的年度及地域间差异及其发生原因

Variation and Its Occurrence Factors of the Appearance Quality of Nonglutinous Rice Grains Among Years and Among Regions,in Cold Region,Hokkaido in Japan

在北海道,作为米粒外观品质的整粒、未熟粒、受害粒、着色粒和死米的各比率以及糙米白度和大米白度都是年度间差异(1999—2006年的6~8年间)比地区间差异(15个地区)大,最大值最小值的差与标准偏差之比平均为1.5~6.4倍。这是由于障碍危险期(出穗前24日之后30天时间)的平均气温和成熟气温(出穗后40天时间的日平均累计气温),其年度间差异与地域差异相比大3.0~3.7倍,而不结实比率、千粒重和糙米产量的生长特性和大米蛋白质含量(蛋白)多1.4~3.3倍的原因。在年度之间,千粒重越重,整粒比率就越高,而整粒比率越高,由于丰产导致蛋白含量就越低。另外,障碍危险期的气温越高,不结实率越低,蛋白含量越低,且成熟气温越高,糙米白度、大米白度也就越高。受害粒和着色粒比率之间存在正相关关系,两种比率在成熟气温分别达到890、850℃之前,成熟气温越高,比率就越低。还有,未熟粒比率在成熟气温808℃时最低,出现二次曲线的相关关系,特别是成熟期间40天的后半部分影响比前半部分大。日照量不足也使未熟粒多发。在地区之间,虽然与年度间相比这些关系基本上还不太明确,但是死米比率在灰色低地土比率较低而泥炭土比率较高的地区,有升高的趋势。现在,这些使米粒外观品质提高的栽培技术在逐渐被开发,并在生产者中被普及和指导。

Appearance quality of rice grains,including percentages of whole,immature,damaged,colored and opaque grain,and whiteness of brown,milled rice were examined in 15 areas of Hokkaido during 1999—2006(6~8 years).The range of the yearly variation in those appearance qualities was 1.5~6.4 times larger than that of regional variation.That was because the annual difference of average temperature and mature temperature(40 days after heading)in sensitive stage to stelile-type cool injury(SSC,24 days before heading and 30 days after heading)is 3.0~3.7 times larger than that of regional difference,while the rate of non seed setting,the growth characteristics of 1000 grain weight and brown rice yield and the protein content of rice are 1.4~3.3 times higher than that of regional difference.Among years,the heavier the 1000 grain weight,the higher the whole grain ratio,and the higher the whole grain ratio,the lower the protein content due to high yield.In addition,the higher the temperature in SSC,the lower the rate of non seed setting,the lower the protein content,and the higher the CSTH,the higher the whiteness of brown rice and milled rice.There was a positive correlation between the ratio of damaged grain and colored grain.The higher the CTAH was,the lower the ratio was before the CTAH reached 890℃and 850℃.Moreover,the ratio of immature grains was the lowest at 808℃and showed a quadratic correlation,especially the effect of the second half of 40 days is greater than that of the first half.The lack of sunshine also makes the immature grains more frequent,too.Among regions,although these relationships are still unclear compared with those among years,the ratio of dead rice trends to increase in areas with low gray soil ratio and high peat soil ratio.At the present,these cultivation techniques that can improve the appearance quality of rice grains are gradually developed,further are popularized and guided by farmers.At the present cultivation techniqures that improve those appearance quality of rice grains have been developed and have disseminated to farmers.