Performance of Rice Cultivars in Various Sawah Ecosystems Developed in Inland Valleys, Ashanti Region, Ghana

Abstract

Experiments were conducted in 2001 and 2002 to evaluate the agronomic responses of 23 rice cultivars with various growth traits in order to select suitable cultivars based on the ecosystems and local farming systems, in the Ashanti region of Ghana. The ecosystems included irrigated sawah* (IS), rainfed sawah (RS) and unbunded and unleveled lowland (UBLL). Two input levels consisted of a high input level (HIL—90 kg N + 45 kg P2O5+ 45 kg K2O ha−1+ herbicide application at 21 d after transplanting (DAT)+ hand weeding at 42 DAT) and a low input level (LIL—20 kg N+farmers’ weed control practices). The results showed that the adoption of the high input level resulted in the increase of the rice grain yield by 100% with a mean yield of 4.2 Mg ha−1, compared with 2.1 Mg ha−1 for the low input level. Rice yield in IS exceeded that in UBLL by 323%, whereas the yield in RS exceeded that in UBLL by 130%. Under the rainfed systems (RS and UBLL), the early maturing cultivars, WAB 208-5-HB, Emokokoo, Bouake189, PSBRC 34 and PSBRC 66 were less affected by the terminal drought that characterized the end of the rainy season, compared with the medium maturing ones such as WITA 1, WITA 3 and IR58088-16-2-2. Interspecific WAB208-5-HB (O. glaberrima×O. sativa) out-yielded most of the improved Oryza sativa cultivars in the UBLL ecosystem under both high and low input regimes.