Effect of Plant Spacing on the Growth and Yield of Rainfed Rice (Oryza Sativa) in the Bimodal Rain Forest Zone of Cameroon

A study was carried out on plant density at the experimental field of the Institute of Agricultural Research for Development (IRAD) Nkolbisson, Yaoundé to determine the appropriate spacing to improve rainfed rice production in the bimodal rainfall forest zone of Cameroon. The experiment was conducted during the main cropping seasons of 2017 and 2018. The planting spacing used were 15cm x 15cm, 20cm x 20cm, 25cm x 25cm and 30cm x 30cm giving the plant populations of 444444, 250000, 160,000 and 111,111 plants / ha respectively using two varieties (Nerica 3 and Nerica 8). The experiment was laid out in a randomized complete block design with three replications. Significant differences were observed in the growth and yield across the years. Treatments were highly significant concerning the number of days to the appearance of the first flower, the number of days to 50% flowering, and the number of days to 50 % maturity. Plants were taller with more tillers and gave higher yields in 2017 than those of 2018. The spacing significantly affected the plant height, number of tillers, and panicle length for both varieties. The interaction of spacing and variety was significant for the number of tillers per m2 and the number of seeds per panicle, however, it was not for the weight of 1000 grains and the percentage of full bales. The yield components determining yield increase were the number of panicles / m2 and the number of seeds/panicles. Nerica 3 variety gave higher yields compared to the Nerica 8, the closer the spacing, the higher the yield. There were a strong significance and positive correlation between yield, number of panicles, and the number of grain per panicle. The spacing that gives the highest number of panicle per m2 was 15 cm X 15 cm and this spacing gave good yield in the region where the study was carried out.