水稻主茎节位分蘖及生产力补偿能力

本研究选用两个籼稻杂交品种西农优1号和冈优725，采用人工去蘖形成分蘖初期的早发、中发、迟发三个处理，在群体条件下研究分蘖和生产力的补偿能力。本研究发现，迟发处理高节位群的分蘖补偿能力最明显，但绝对补偿量小。迟发处理高节位群的生长势、有效分蘖倍数增加，抽穗期单茎叶面积有增加的趋势，但抽穗期有效穗数、叶面积系数降低；迟发处理冠层光分布增加，叶绿素、蛋白质含量提高，叶片细胞内保护酶类(Superoxide dismutase, SOD、catalase，CAT)活性下降慢，叶片衰老慢，但是漏光率增加，截光率下降；迟发处理净光合生产率（Net assimulation rate, NAR）增加，同化物分配合理，经济系数有增加的趋势，但物质积累速度（Crop growth rate ,CGR）和干物质生产量减少。在本实验条件下，早发与中发处理的经济产量差异不显著，但早发与迟发处理的经济产量差异达极显著。本研究结果表明大苗秧对生物、非生物因素胁迫，如本田前期一定程度的人工去蘖，具有一定的分蘖补偿能力。

The compensation capacity of tillering and production of main stem nodes in rice

Two O. indica hybrid rice cultivars, Xinongou 1 characterized with high tiller and Gangyou 725 characterized with high yield potential, were used to investigate the compensation capacity of tillering and production of main stem nodes by artificially specific tiller removal treatment in the initial tillering stage under population condition. The tiller removal treatments included the early tiller emerge that doesn't remove any tiller, the middle tiller emerge that removes the first primary tiller, and the later tiller emerge that removes the first and second primary tillers. The result showed that the canopy light distribution is an important environment factor affecting the compensational capacity of tillering, and the tillering compensational capacity of upper node group was higher than that of middle and low node group under enough water and fertilizer. Compared with the early tiller emerge treatment, in the morphological characteristics, the later tiller emerge treatment reduced the leaf area index, improved the light intensity or quality of stem base, delayed the shade escape, and promoted the differentiation and growth of upper node tiller, increased the growth potential and effective tiller multiple in the upper node group and increased the single stem leaf area in the heading stage. However, the tiller development characteristic of upper node group reduced the effective panicles and leaf area index, so the absolute compensation capacity was low. In the ecological and physiological characteristics, the canopy light distribution, chlorophyll and protein content increased, and the activity of cell protective enzymes (superoxide dismutase, SOD; catalase, CAT) drop slowly, and the leaf senescence rate delayed, whereas the light penetration loss rate increased and the light interception rate decreased. In the material production and distribution, the leaf net assimilation rate (NAR) increased, assimilation allocation was reasonable, and the economic coefficient had an increasing tendency. The leaf area index reduced, the crop growth rate (CGR) decreased, dry matter accumulation significantly decreased, and the coordination between material production and distribution changed. In the present experiment condition, no significant difference of economic yield existed between the early tiller emerge treatment and the middle tiller emerge treatment, but extremely significant difference of economic yield existed between the early tiller emerge treatment and the later tiller emerge treatment. The present study indicated that the big seedlings have some extent compensation ability of tillering for the biotic and abiotic stress like the artificially specific tiller removal in the initial tillering stage, and the compensation ability exhibited in increasing the growth potential in the tillering stage, increasing the single stem leaf area and canopy light distribution in the heading stage, and delaying the last leaf senescence rate and increasing the NAR and economic coefficient in the mature stage.