DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF
THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN CROP SCIENCE OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA.
2016
Field experiments were conducted in two seasons at Sokoine University of Agriculture farm in Morogoro, Tanzania (6.850S; 37.640E and 568 m.a.s.l.) during the short rain (November 2014 to January 2015) and the long rain (March to June 2015). The experiment was a split plot in a randomized complete block design (RCBD) with 4 replications. Weed management practices (pre-emergence (ULTRA 2, 4-D), post-emergence (Hansunil), hoe weeding (3x) and weedy) were the main plot treatments and four rice genotypes (NERICA-1, NERICA-4, NERICA-7 and Mwangaza) were the subplots. Significant differences (P<0.05) were recorded for weed counts among weed management practices. The dominant weed group, as determined by the Summed Dominance Ratio (SDR), in both experiments was broadleaf species (50.8%) followed by sedges (25.2%) and grasses (24.0%). Post-emergence (8.6%) and hoe weeding (12.3%) significantly reduced weed dry biomass compared to pre-emergence (17.8%) and weedy (61.3%) in 2014/15 and 2015 experiments respectively. Significant differences (P<0.05) were recorded among the rice variables. Mwangaza and NERICA-1 were recorded with the tallest and shortest plant height (129.8cm and 39.1cm) respectively for weed management practices in both experiments. Mwangaza and NERICA-1 was recorded with the highest and lowest tiller (35.3/m2 and 7.5m2) respectively. Mwangaza and NERICA-7 was recorded with the lowest and highest LAI (2.5 and 4.5) and NERICA-7 showed the highest and lowest (1603g/m2 and 305.1g/m2) straw biomass in both experiments. Rice grain yield were highest for NERICA-1 in hoe weeded and plots applied with post-emergence herbicide (2187.5kg/ha and 1562.5kg/ha) > pre-emergence (965.9kg/ha) and weedy plots (0.0kg/ha) 2014/15 experiment and post-emergence and hoe weeded plots (4630.6kg/ha) and (4176.1kg/ha) > pre-emergence (3323.8kg/ha) and weedy plots (0.78kg/ha) 2015 experiment. The highest net return (3 352 846 Tshs) was obtained on NERICA-1 in post-emergence plots, this was also similar (P<0.05) to hoe weeding plots. Hansunil was also effective in weed control and had significant effect on profit analysis should be used in combination with hoe weeding under integrated weed management.