Performance of Near-Isogenic Genotypes of Rice Differing in Growth Duration. I. Yields and Yield Components1
- Tran Van Dat and
- M. L. Peterson2
The yields of the full-season (approx. 160 days) rice (Oryza sativa L.) cultivar Calrose 76 was compared with a spontaneous mutant from it identified as ED7 which has an 18-day shorter vegetative growth period when both are sown in early May. The mutant ED7 is less sensitive to photoperiod than Calrose 76. The objective was to determine the effect of a shorter vegetative period on yield and yield components. Field trials were conducted in an environment having cool temperatures both early and late in the growing season. Cold nights about 2 weeks prior to heading can induce floret sterility. Under these conditions, ED7 yielded significantly more than Calrose 76 for both early (11 May) and later (21 May) sowings with the later sowing trial yielding significantly more than the earlier one. Calrose 76 yielded significantly more from the early than the late sowing thus resulting in a highly significant interaction between genotypes and sowing dates. Yield component analysis disclosed that ED7 had significantly higher 100-grain weights, and fewer sterile florets than Calrose 76 for the later sowing. Cool night temperatures appeared to adversely affect Calrose 76 causing more sterility in the late-sown trial and incomplete grain filling. Increased N fertilizer rates significantly increased grain yields, LAI, and panicles/m2, but decreased 100-grain weights, and percent fertile florets. The genotype with shorter vegetative growth period (ED7) was more efficient in this cool environment.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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