Effect of Seed Rate on Yield and Yield Components of Aerobic Rice (Oryza sativa L.) Under White Nile State Conditions

Abstract

A field experiment was conducted for two consecutive seasons
(2014 and 2015), at the White Nile Research Farm, Kosti, White Nile
State, Sudan, to determine the seed rate for aerobic rice (Oryza sativa L.).
The variety Kosti1 was sown directly on flat dry soil with varying seed
rates: 40, 60, 80 and 100 kg/ha. The experiment was arranged in a
randomized complete block design with three replications, in the two
seasons. The land was pre-irrigated and then disc harrowed and leveled.
The crop was planted during the first week of July in both seasons.
Characters studied were, Phenology, yield, biological yield and yield
components. The combined and single analyses of variance for both
seasons showed that seed rate treatments exhibited highly significant
differences in grain yield and yield components. The results showed that,
increasing seed rate significantly increased number of panicles/ m2, the
percentage of empty grains, plant height, grain yield and biological yield.
However, increasing seed rate reduced days to 50% flowering, the filled
grains and the 1000- grain weight. The results indicated that the seed rate
(80 kg/ha) significantly increased the number of panicles/m2, biological
yield and grain yield (kg/ha). The lowest and the highest yields/ha were
obtained at the seed rates of 40 and 80 kg/ha, respectively. The results
indicated that, increasing seed rate from 40 to 60 kg/ha increased grain
yield by 10 % and 16 % in the first and second seasons, respectively; and
that grain yield could be improved significantly in the two seasons by 6 %
and 18 % by increasing seed rate from 60 to 80 kg/ha. However,
increasing seed rate from 80 to 100 kg/ha reduced the grain yield by 17 %
and 23 % in the first and second seasons, respectively. The highest
marginal rate of return (MRR) 1496 % was obtained from the 80 kg/ha
seed rate. Therefore, it is concluded that the optimum seed rate under the
conditions of the present investigation was 80 kg/ha.