EFFECTS OF VARIETY, SPACING AND SOIL AMENDMENT ON GROWTH, YIELD AND MILLING QUALITY OF RICE (Oryza sativa L.) IN THE GUINEA SAVANNAH ZONE OF GHANA

Abstract

Low soil fertility, lack of high-yielding varieties and poor planting methods hinder rice production in the Northern region of Ghana. It is against this background that research comprising survey and field experiments were conducted in the Sagnarigu and Kumbungu districts of the Northern region of Ghana. The survey was carried out to determine the perception and knowledge of rice value chain actors on the effect of improved practices on yield and milling characteristics of rice in the study area using multi-stage sampling and questionnaire administration. Survey results indicated that rice production is hindered by by the use of poor variety, poor spacing, poor time of transplanting and the incidence of low soil fertility in both low land and irrigated rice ecosystems of the study areas. Three field experiments were conducted. Field experiment I was carried out in the 2021 rainy season to evaluate the effects of time of transplanting and spacing on growth and yield of rice. Field experiment II was a repetition of field experiment I but was conducted under irrigated conditions in Bontanga in the Kumbungu district. Field experiments I and II were a 4 x 5 factorial experiments laid out in a randomized complete block design. The factors include four levels of spacing and five levels of time of transplanting. Data were collected on the growth and yield parameters of Agra rice as well as value cost ratio. Under the rainfed condition, plants from 25 cm x 25 cm plots where seedlings were transplanted at 21 days after planting produced the highest yield with a value of 9194 kg ha-1 whereas plants from 20 cm × 20 cm plots where seedlings were transplanted at 21 days after planting produced the highest value cost ratio with a value of 1.42. Under the irrigated condition, plants from 20 cm × 20 cm plots where seedlings were transplanted at 21 days after planting produced the highest grain yield and value cost ratio with values of 7810 kg ha-1 and 1.10 respectively. Field experiment III was carried out in the 2022 cropping season to determine the effect of variety, spacing and soil amendments on growth, yield, and milling characteristics of rice using a 5 x 2 x 4 factorial experiments laid out in a randomized complete block design (five levels of rice variety, two levels of spacing, and four levels of soil amendment). Results of experiment III indicated that Gbewaa variety transplanted at 25 cm x 25 cm spacing with 37.5 kg/ha N, P and K + 26.25 kg/ha N applied and Agra variety transplanted 20 cm x 20 cm spacing with 37.5 kg/ha N, P, and K + 26.25 kg/ha N applied produced highest effective tiller count per plant with values of 20.78 and 18.67 respectively. The post experiment soil analysis showed that soil amendment 10 t/ha Deco compost + 18.75 kg/ha NPK + 13.13 kg/ha N maintained total N and increased K, Ca and Mg in the soil. The highest grain yield was obtained from Agra variety transplanted at 25 cm x 25 cm spacing on plot where 37.5 kg/ha N, P, and K + 26.25 kg/ha N were applied. Similarly, Gbewaa variety transplanted at 20 cm x 20 cm spacing, on plot where 37.5 kg/ha N, P and K + 26.25 kg/ha N were applied produced high grain yield. Mandii rice variety transplanted at 20 cm x 20 cm spacing on plot where 37.5 kg/ha N, P, and K + 26.25 kg/ha N were applied also produced high brown yield, grain length and grain length-width ratio. Mandii rice is a local variety and incorporating it with varieties of good milling characteristics through breeding would make a positive impact in the rice business in the study area. The application of 37.5 kg/ha NPK + 26.25 kg/ha N has the potential to promote plant growth and yield while soil amendment 10 t/ha Deco compost + 18.75 kg/ha NPK + 13.13 kg/ha N would improve the soil physical and chemical properties.