GROWTH AND YIELD OF ADVANCED BREEDING LINES OF MEDIUM GRAIN RICE AS INFLUENCED BY DIFFERENT TRANSPLANTING DATES
M. E. Safdar, I. R. Noorka, A. Tanveer, S. A. Tariq and S. Rauf
University College of Agriculture, University of Sargodha-Pakistan
*Social Science Division, National Agriculture Research Council, Pakistan
Directorate of Research, University of Agriculture Faisalabad
Corresponding email: ijazphd@yahoo.com
ABSTRACT
Rice plant was considered sensitive to heat stress especially during reproductive growth phase. Eight medium grain rice accessions: 999421, KSK 401, KSK 402, PK 7797-1-2-1, KSK 301, KSK 418, KSK 406 and KS 282 were sown on five different sowing dates: 16th April, 1st May, 16 May, 1st June and 16th June during summer seasons of three successive years from 2004 to 2006 to access their growth and yield performance under earlier, mid and late sown conditions. Experiment was laid out in split plot design. Accession × sowing date interaction remained significantly different for all traits studied. The differential yield response of accessions to various sowing dates was found to be due to their differential tolerance against high temperature stress at vegetative and reproductive growth phases. On an average, 12% and 9% reduction in paddy yield was obtained in sowing dates where heat stress coincided with reproductive and seedling growth, respectively. Paddy yield and number of grains panicle-1 increased with delay in sowing time up to 16th May whereas days to 100 % flowering, tillers hill-1 and plant height decreased with delayed sowing. Among yield components number of grains panicle-1 showed positive linear relationship (R2=0.40) with paddy yield which means yield gains were attributed to higher number of grains panicle-1 rather than higher number of tillers hill-1. Maximum number of grains panicle-1 and paddy yield of almost all rice accessions under mid sown conditions (16th May) seem to be associated with non-coincidence of their reproductive growth periods with heat stress as occurred in early sown conditions (16th April, 1st May).
Key words. Accession, Paddy, Reproductive, sowing dates, yield performance.
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