Yield and yield components of IR varieties and lines with different growth duration
1988
Sta Cruz, P.C. | Aragones, D.V. | Wada, G. (International Rice Research Inst., Los Banos, Laguna (Philippines))
Yield and yield components of rice varieties and advanced lines with different growth durations (GD) were investigated under 0 and 90 N kg/ha: 45 in the 1986 dry season (DS), 62 in 1986 wet season (WS) and 64 in 1987 DS. The varieties were grouped as very early (Ve, 110 d), early (E, 110-120 d), medium (M, 121-130 d) and long (L,130 d) duration. Maximum grain yield, sink size, N contribution to sink formation (S/N) and N harvest index (NHI) were associated with GD. Optimum GD at 90 kg N/ha for grain yield120d. The low grain yield of VE and E duration varieties is due to limited sink size. Low sink degeneration and high ripening percentage were masked by the effect of limited sink. Low grain yield of long duration varieties is due to large amount of degenerated sink as compared with optimum GD. The high sink degeneration is due to low N content from late spikelet initiation to flowering. The low grain yield in this group resulted from low S/N, NHI, and percent ripening compared with the medium duration varieties.
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