Combined Effect of Doses of Fertilizer and Different Densities on Agronomic Parameters of Rice (Oryza sativa (L.)) Adapted in Humid Area in The Valley of Benoué, Cameroon

The study was conducted on July 2021, at the Institute of Agricultural Research for Development (IRAD). The main objective of the study was to determine the dose of mineral fertilizers and densities which respond well to the rice culture, variety Nerica L36 in a humid area of the valley of Benoué. Fertilizers doses were: T1 (0 kg NPKSB+100 Kg Urea/ha); T2 (150 kg NPKSB+100 Kg Urea/ha); T3 (200 kg NPKSB+100 Kg Urea/ha; T4 (250 kg NPKSB+100 Kg Urea/ha). Three densities were considered: De1= 20 cm x 20 cm; De2= 25cm x 25cm; De3= 30 cm x 30 cm. The experimental design was a split-plot, with two factors in three replications: Factor 1 concerning fertilizers doses and Factor 2 relating to densities. Evaluation parameters were: the height of plant, the number of tillers, the number of panicle/plants, length of panicles, heading date at 80 % and maturity date. Harvest data collected were: the number of grains/panicles, weight of 1000 grains, potential yields. The results showed that the effect of different amounts especially doses 2, 3 and 4 were highly significant (P≤0.05) in influencing the height of plant, number of tillers, number of panicles/plants, length of panicles for all densities. These densities were considered suitable for growing aspect of rice. On the other hand, the densities 1 and 2 were suitable for the element of heading date at 80 % for the doses 1 and 2, maturity date with dose 1. However, yield aspects were most significant (P≤0.05) with the dose 2, 3 and 4 on a number of grains/panicles and potential yield especially, which permit us to deduce that densities 1, 2 and 3 were suitable for these yield parameters