J Integr Plant Biol. ›› 1977, Vol. 19 ›› Issue (1): -.

• Research Articles •    

The Relation between LAI, Leaf Openness and Solar Energy Utilization in Rice

Laboratory of Rice Ecology, Kwangtung Academy of Agricultural Science   

Abstract: Using medium maturing varieties of early rice from Kwangtung province as ma- terials (Pearl dwarf etc.) and by method of varietal comparison, we have made inves- tigations on some physiological and ecological factors which affect rice yield. On the basis of experimental results obtained in our laboratory some approaches of increasing the efficiency for solar energy utilization and the apllication of these results to rice breeding, reform of cultivation system and high yielding culture measures have been discussed. Our experimental results obtained in 1974 and 1975 showed that a significant positive correlation is present between rice yield and the sum of leaf arza indices (LAI) at young panicle differentiation, full (80%) heading stage and 20 days after full heading stage. In case of LAI values less than 6, there is also a significant positive correlation between canopy net photosynthesis rate and LAI. In case where LAI values are higher, those varieties with little leaf openness all give move grain yield than variety with greater leaf openness (except for one variety lodging). In 1974 the total solar energy during the 90 days after transplanting was more than that in 1975, and the average grain yield in 1974 was also higher than that in 1975. The relationship between rice yield and LAI, leaf openness, solar energy can be expressed by a linear regression equation with three arguments. Using the method of so-called "cyclic prediction" (an unpublished new method) to examine the exactness of such a regression, the average error between calculated and actual values of rice yield is 2%, the maximum error is 5%. This indicates that the above three are indeed important factors affecting rice yield.

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