Effect Of Seedling Age on Growth And Yield of NERICA 4 Rice

The age of seedlings at transplanting is an important criterion in rice production as it primarily contributes to the number of tillers produced per hill and significantly affects growth and grain yield of rice. We examined the effect of seedling age at transplanting on growth and yield of NERICA 4 rice to ascertain the suitable age that will give optimal growth and yield. Four seedling ages (treatments) namely 14 Days (14DAS), 21 Days (21DAS), 28 Days (28DAS) and 35 Days (35DAS) were transplanted at the experimental field of Tsukuba International Center (Field A-1-3) in Tsukuba city of Japan, in a randomized complete block design (RCBD) with 3 replications. Plant length, tiller number and leaf color were monitored from 20 days after transplanting till heading stage. Yield and yield components were analyzed at physiological maturity.  Seedling age at transplanting had a significant effect on plant length, tiller number and leaf color but had no significant effect on yield and yield components. 14DAS seedlings had special ability to increase number of tillers (13), overall plant length at heading (106.9cm), number of panicles per square meter (266.6) and harvest index (0.46). Along with 21DAS seedlings, 14DAS seedlings recorded a lower grain yield (4.9 ton/ha) than 35DAS seedlings (5.0 ton/ha) due to a lower ripening ratio (64.8% for 14DAS and 66.6% for 21DAS) and lower 1,000 grain weight (19.0g and 20.5g respectively). 28DAS seedlings had the lowest yield (4.6 ton/ha) due to lowest number of panicles per square meter (229.6), lowest number of spikelet per panicle (105.7) and lowest ripening ratio (66.2%). In terms of panicle length, 35DAS obtained a higher value than 14DAS which was the lowest. It was observed that ripening ratio, 1000 grain weight and panicle length tend to increase with age of seedlings, but the differences were statistically insignificant. The study showed that transplanting seedlings older than 14 days does not significantly increase paddy yield and its components. However, there is an opportunity of significantly increasing the yield and yield components of 14DAS seedlings by increasing the amount of Nitrogen fertilizer applied at panicle initiation.