Growth dynamics, root development and yield potential of low tillering new plant type of rice.
1991
Aragones D.V. | Janoria M.P. | Yamauchi M.
The new plant type prototypes IR66073-10-1-3 and 57-11-4-2, which are characterized by low tillering, thick leaves and big panicles, and modern high yielding variety IR68 were transplanted at the spacings of 20 cm x 30 cm and 20 cm x 10 cm during 1991 dry season to evaluate their performance. Tiller number of the prototype was significantly fewer than that of IR68 throughout the growth stages. Net assimilation rate (NAR) of the prototype was higher than IR68, which was ascribed to the thicker leaves and higher N concentration in leaves. However, crop growth rate (CGR) was more controlled by leaf area index (LAI) than by NAR. Thus, the prototypes had lower CGR than IR68, resulting in lower dry matter production. At heading stage IR68 had higher root length density in the supper soil layer (0-10 cm) than the prototypes while the prototypes accumulated more roots in the deep layer (20-40 cm) than IR68. Roots of prototypes were thicker than that of IR68. Grain yield of the prototypes was less than that of IR68 (4.0-5.2 VS. 6.9 t/ha), which was due to the decrease in spikelets/sq m. The panicle size of the prototype (122-177 spikelets/panicle) was not large enough to compensate for the decrease in spikelet/sq m caused by the panicle number reduction. The prototypes are inferior to the high tillering variety in dry matter production, nutrient uptake from the plow layer, and sink capacity.
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