Effect of Weeding Regime and Row Direction on Growth and Yield of Upland Rice in Uganda

Abstract

A study determined the effects of row direction and integrated weed management on the growth, productivity and economics of upland rice at Ikulwe Research Station using a completely randomized block design, replicated thrice with NAMCHE 5 upland rice in Uganda (2021b & 2022b). 12 treatments with 6 weeding regimes namely Pre- emergence Butanil (PREB) + 1hand hoeing (HH), 2HH, 3HH, PREB + Post emergence Butanil (POEB), weekly weeding (42 days) and control (EW & NS orientation) were adopted. Nitrogen (100 kg) Phosphorus (60 kg) and Potash (40 kg) were applied ha-1. Collected data on plant height, tillers, leaves, panicles; and grains were subjected to ANOVA (13th edition Genstat). Higher growth and yield parameters were in EW than NS direction. Leaves (27-28 leaves), height (65-70 cm), tillers (5-6 tillers and panicles (4-5 panicles) plant-1 were high under 2HH, PREB +1HH, PREB + POEB and 3HH (EW) compared to similar treatments in NS direction during 2021b and 2022b. Grain yield (2.34 t ha-1; HH), (2.26 t ha-1; PREB + 1 HH), (2.01 t ha-1; PREB + POEB), (1.89 t ha-1; 3HH) was significantly high in 2021b. During 2022b increased panicles (4-5 panicles), panicle length (21 cm), grains panicle-1 (110-117 grains) and grain yield (3.8 - 4.4 t ha-1) were recorded relative to 2021b. Weekly weeding (EW) developed high grains panicle-1 (102 grains) and grain yield (3.0 t ha-1) in 2022b relative to reduced tillers (4.5 tillers), filled panicles (3.6 panicles) and grain yield (1.9 t ha-1) in 2021b. Row directions had no effect on leaf width and grass biomass was numerically higher under EW than NS direction. Benefit Cost Ratios and Marginal Rate of Returns were optimum under 2HH and PREB + 1HH (EW). 2HH and PREB + 1HH (EW) may be recommended in Uganda having been the most economic technologies.

Performance of Direct-Seeded Upland Rice-Based Intercropping Systems Under Paired Rows in East-West Orientation

“…Rice, beans, soybeans and groundnuts being C 3 plants are not efficient in utilizing Cabondioxide like C 4 crops. Kaiira et al (2023) recorded higher rice growth and grain yields in the East-West row orientation. Borger (2020) reported that East-west crops more effectively shade weeds in the inter-row space than NS row crops.…”

“…This may be related to more efficient absorption of solar radiation under competition between rice and the phenotypically tall soybean crop planted in the East-West row direction. Kaiira et al (2023) reported that rice being a C 3 plant produced higher rice growth and grain yields in the EW row direction due to reduced weeds, more efficient in utilizing Cabondioxide and solar radiation. Similar observations were earlier made by Borger (2020).…”

“…The rice yield gain in 2023 may be attributed to benefits from intercropping the early maturing beans with rice in the EW row direction with rice. Rice and the beans are all C 3 plants which increase in productivity in EW row direction, due to high photosynthetically active solar radiation, water, temperature and nutrients (Kaiira et al, 2023). The increased rice yields could be attributed to physiological and nutritional gains by rice following the harvest of early maturing beans relative to late maturing groundnuts and soybeans.…”