Yield and Some Agronomic Characteristics of Rice (Oryza sativa L.) Genotypes in Response to Source-Sink Limitations

Abstract

To study the effect of source and sink limitation on grain yield and yield components of four genotypes of rice, a field experiment was conducted at Rice Research Station of Tonekabon, Iran during 2013-2014 growing season. The experiment was carried out with a factorial arrangement based on randomized complete block design with four replications. Factors were four rice genotypes (promising line 12, 13, 14 and 18) and four levels of source-sink limitation (control, defoliated all leaves except flag leaf, only flag leaf removal and removal of ⅓ end of panicle). Traits such as grain yield, biological yield, harvest index, tiller number, 1000-grain weight, and panicle fertility were measured. Analysis of variance indicated that effect of genotypes was significant for all of traits except harvest index (P < 0.01), while the effect of source-sink limitation was significant for the most traits except harvest index and tiller number. Comparison of means indicated that promising line 12 had the highest grain yield, biologic yield, and 1000-grain weight. Also, among source-sink limitation treatments, the highest values for all traits were recorded for control treatment, while the lowest ones were observed for the removal of ⅓ end of panicle. Results indicated that all genotypes showed both source and sink limitations. Furthermore, by imposing source limitations (particularly defoliated all leaves except flag leaf), increasing in 1000 grain weight of genotypes was more than control and this indicates that there was a source limitation. Generally, this experiment illustrated that yield of the some rice genotypes is sinklimited (Line 12 and 18) and other genotypes (Line 13 and 14) are source-limited and breeding rice with the larger sink or source size in the current genotypes may increased yield potential.