Correlation between Grain Yield and Related Characters in Restorer Lines of Rice under Low Nitrogen Application

Abstract

This study was conducted to determine the correlation of grain yield and related characters in 10
rice restorer lines for thermo-sensitive genic male sterile lines under low nitrogen level (60 kg N /ha)
and normal level (120 kg N/ha) with a constant phosphorus and potassium application in both spring
and autumn cropping seasons. In each experimental plot, ten plants were randomly selected for
measuring number of tillers at different growth stages. At the flowering stage, ten plants of each plot
were selected for measuring flag leaf sizes and leaf nitrogen content. The result showed that most  
agronomic characters  viz., whole-plant dry matter weight, number of panicles per plant, number of
spikelets per panicle in all restore lines were higher under normal N condition than those under low N
condition in both cropping seasons. Grain yield was positively correlated with whole-plant dry weight
in all restorer lines under both N conditions. In  both cropping seasons, a positive correlation was
observed between grain yield and flag leaf N content under the low N condition, whereas it was not
significant under the normal N condition. Under low N condition, grain yield was significantly and
positively correlated with both the percentage of filled grain and 1000-grains weight in spring season,
whereas it was positively correlated with both the number of panicles per plant and percentage of filled
grain in autumn season. Thus, besides whole-plant dry weight, other indicators used for selecting
restorer lines under the low N condition would be the filled grain rate and 1000-grains weight in spring
and the number of panicle per plant and filled grain rate in autumn season.