Effects of Plant Spacing, Row Spacing and Seedling Number Allocation on the Growth Dynamics of Different Populations of Two Types of Rice Varieties.

[Objectives] This study was conducted to construct high-yielding, high-quality, and high-light-efficiency population structures of different types of rice varieties. [ Methods] The effects of plant spacing, row spacing and seedling number allocation on stems and tillers, leaf area and dynamic traits of high-yielding rice populations (more than 9 750 kg/hm2 ) and low-yielding populations (less than 9 750 kg/hm2 ) were studied by two kinds of representative rice varieties with different tiller ability and panicle sizes in cold regions. [Results] Decreasing the plant and row spacing and increasing the number of planted seedlings per hole advanced the heading date and made the number of stems and tillers in the population increase. The impact on the super rice variety with fewer tillers and heavier panicles was greater than that of conventional variety with more tillers and lighter panicles. The stems and tillers of the high-yielding high-quality populations grew steadily in the early stage of development, until an appropriate number of panicles was reached at the critical leaf age for productive tillers (June 25 ), and the peak seedlings should appear in the jointing stage (July 9) with a small number ( that value of Longjing 21, the super rice variety with fewer tillers and heavier panicles, was about 1. 2 times the expected panicle number, and that of the conventional variety with more tillers and lighter panicles, Kongyu 131, was about 1. 1 times the expected panicle number). The populations gradually declined since then, until reaching an appropriate number of panicles at the heading stage. The high-yielding high-quality populations had a higher leaf area index at the heading stage. The value of Longjing 21, the super rice variety with fewer tiller and heavier panicles, reached about 6. 0, and that of Kongyu 131, the conventional variety with more tillers and lighter panicles, reached about 4. 5. The values decreased thereafter. At the maturation stage, the leaf area index of Longjing 21 remained above 2. 5, and that of Kongyu 131 remained above 2. 0. [Conclusions ] This study has an important guiding role and significance for their high-yielding and high-quality supporting cultivation in cold regions. [ABSTRACT FROM AUTHOR]