An Analysis of N Nutrition on Yield and Yield Components for the Improvement of Rice Fertilization in Korea
1979
Vlek, P. L. G. | Hong, C. W. | Youngdahl, L. J.
The statistical procedure of path coefficient analysis was applied to five field experiments conducted in Korea to help set criteria for the development of new controlled-release fertilizers and fertilizer management practices tailored to flooded rice. The yield components which are most sensitive to N nutrition and the growth stages when N uptake is most efficiently translated into yield component development were identified. The experiments were conducted over a period of 2 years using two varieties of rice (Oryza sativa L., var. Tongil and Jinheung), two water management regimes (continuous and intermittent flooding), and three fertilizer sources (regular urea and two sulfur-coated ureas) applied at four or five different levels of N. Continuously flooded experiments were conducted on an Aquic-Flnventic Eutrochrept and the intermittently flooded on an Aquic-Udipsamment. Yield response to N and apparent fertilizer N recovery varied with N source, rate, and variety, but in an inconsistent pattern. Close examination of yield component development as a function of N uptake revealed that variations in yield were mainly determined by panicle density and number of spikelets per panicle; the product of these components can serve as a potential yield index (PYI). The PYI is, to a large extent fixed by heading time and is closely related to the amount of N taken up between transplanting and heading. Path coefficient analysis was used to ascertain that N uptake during the period between 2 weeks after transplanting to maximum tillering most critically influenced PYI.
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