一、从709个水稻品种剑叶克穗面积(剑叶面积cm~2/穗重克)的次数分布图看出:无论籼粳稻,都呈一尖峰偏态曲线,40％个体的克穗面积集中在11cm~2左右;80％以上集中分布在9～15cm~2。克穗面积在9cm~2以下的占很少数,它们多数的结实率高、穗粒数偏多,剑叶面积不大;克穗面积偏大或特大的品种,多数是结实率低等特殊原因。克穗面积之所以比较集中,主要是由于剑叶面积和穗重有极显著的正相关的关系。二、克穗面积随栽培条件(如年度、施肥量、密度等)不同而有一定变动。特别是施用过量氮肥的情况下,一些不耐肥的品种,显著增大。但在相对相同(主要是施肥水平)条件下栽培则变动范围比较小。即使有变动,品种间的相对关系仍基本一致和相对稳定。克穗面积小的品种,除了上述原因外,是否与叶片的净同化率高有关,很值得研究。三、1978—1979年的试验资料表明,各品种克穗面积的大小与产量呈负相关的趋势,多数达到显著程度。1979年的试验结果,较高产品种的克穗面积在13～17cm~2之间,超过20cm~2以上的产量都不高,但也有少数品种克穗面积相当小而产量不高的情况。表明适当克穗面积应有一定限度和较宽的范围。这个比较适当的范围,仅反映个体叶面积和穗重平衡的结局关系,可供栽培和育种上的参考。 The distribution of number of spike area (leaf area cm ~ 2 / spike weight) of 709 rice cultivars showed that there was a peak skew curve in both indica and japonica rice, and spike area in 40% of individuals Concentrated in about 11cm ~ 2; more than 80% concentrated in 9 ~ 15cm ~ 2. Spike area in 9cm ~ 2 accounted for a very small number of most of their high seed setting rate, grain number is too much, not large area of ​​the flag leaf; spike area is too large or extra large varieties, most of the low seed setting rate the reason. Spike area is more concentrated, mainly due to the flag leaf area and ear weight has a significant positive correlation. Second, the spike area with the cultivation conditions (such as annual, fertilizer, density, etc.) different and have some changes. In particular, the application of excessive nitrogen fertilizer, some of the non-fattening varieties, significantly increased. However, in the relatively same (mainly fertilization level) under the conditions of cultivation is relatively small range of change. Even if there is a change, the relative relationship among cultivars is still basically the same and relatively stable. In addition to the above-mentioned reasons, it is worth to study whether the species with small spike area is related to the high net assimilation rate of leaves. Third, the experimental data from 1978 to 1979 showed that the spike area of ​​each variety had a negative correlation with the yield, most of which reached a significant level. The test results of 1979 showed that the spike area of ​​the higher-yielding cultivars ranged from 13 cm to 17 cm-2 and the yield of more than 20 cm-2 was not high. However, there were also a few spikelets of a few cultivars with relatively low yield. That the appropriate spike area should have a certain limit and a wide range. This more appropriate range, only reflect the individual leaf area and the relationship between the outcome of the balance of ear weight, for cultivation and breeding on the reference.