Optimal seed rate and planting technique determination for high productivity in rice (Oryza sativa L.) varieties in the Southern Guinea Savannah of Nigeria

Abstract

Lack of an established planting techniques and continuous usage of high seed rates have contributed to major challenges of achieving food security and high productivity in rice seed production in Nigeria. There are obvious variations in these two factors being currently used by different farmers, seed companies and research institutions. In this paper, field trials were conducted during the 2019, 2020 and 2021 rainy seasons at the research field of the National Agricultural Seeds Council, Sheda, Abuja, Federal Capital Territory, Southern Guinea savannah zone, Nigeria. A split-split plot design in three randomized blocks (replicates) was employed to determine the optimum combination of planting techniques and seed rates aimed at achieving high yield for rice seed production in Nigeria. The four (4) varieties used (FARO 44, FARO 59, FARO 66 and FARO 67) were laid out as main plot; Planting techniques at three (3) different planting techniques: dibbling, broadcasting and transplanting) as sub-plot; and seed rate at three (3) levels (25, 50 and 75kg/ha) as sub-subplot. A multi-dimensional scale analysis was explored to look at different dimensions of the result for 2019, 2020, 2021 and combined-years analysis. From the result, Interactions between planting technique and seed rate for optimum seed yield per hectare revealed that in combined-year, broadcast, dibbling and transplant planting techniques with seed rate of 50 kg/ha (3.37 t/ha), 50 kg/ha (3.58 t/ha) and 25 kg/ha (3.43 t/ha) respectively were significant. Response surface regression shown that the transplant planting technique with seed rate of 44 kg/ha sprung up unexpected increase in seed yield when subjected to total weed count (from 4.065 t/ha to 6.625 t/ha) which otherwise shows the suppressing effect of the independent variable (transplant planting technique) on weed. Transplant and dibbling planting techniques with seed rates of 42 and 40 kg/ha respectively produced optimum seed yield between 4.96 t/ha and 5.60 t/ha. It is therefore concluded from the response surface regression analysis that dibbling planting technique + 40 kg/ha seed rate and transplant planting technique + 42 kg/ha seed rate were the most productive and optimal combination for planting a hectare of rice field with enhanced productivity. But result from the ANOVA interactions of planting technique and seed rate established that the combination of (broadcast + 50 kg/ha), (dibbling + 50 kg/ha) and (transplant + 25 kg/ha) were optimal for high productivity per hectare in rice field establishment. Considering the effect of weed, it is concluded that transplant planting technique with an increased seed rate of 44 kg/ha could be recommended as the best planting technique and seed rate with suppressing effect on weed.