Light and water are among essential resources required for production of photosynthates in plants. A study on the effects of weeding regimes and maize planting density on light and water use was conducted during the 2001/2 short and 2002 long rain seasons at Muguga in -the central highlands of Kenya. Weeding regimes were: weed free (W1), weedy (W2), herbicide (W3) and hand weeding twice (W4). Maize planting densities were 9 (D1) and 18 plants m -2 (D2) intercropped with Phaseolus vulgaris (beans). The experiment was laid as randomized complete block design replicated four times and repeated twice. All plots were thinned to 4 plants m -2 at tasseling stage (96 DAE) and thinnings quantified as forage. Soil moisture content (SMC), photosynthetically active radiation (PAR) interception, evapo-transpiration (ET crop), water use efficiency (WUE), and harvest index (HI), were determined. Percent PAR was higher in D2 than in D1 before thinning but higher in D1 than in D2 after thinning in both seasons. PAR interception was highest in W2 but similar in W1, W3 and W4 in both seasons. SMC was significantly lower in W2 but similar in W1, W3 and W4. D2 had lower SMC than D1 in season two. Weeding regime significantly influenced ET crop, while planting density and weeding regime significantly influenced WUE and HI. D2 maximizes water and light use for forage production but results to increased intra-specific plant competition for water and light severely before thinning (96 DAE) that reduce grain yield in dual purpose maize, relative to D1.
The aim of this study was to investigate the effects that supplemental irrigation (SI) has on the Kale (Brassica Oleracea) crop yields as compared to the wholly rain-fed crop. The experiments were conducted in Kieni, Central Kenya where the rainfall pattern was bimodal. The planting for rain-fed crops was done in three blocks, each measuring 10×1 m with a spacing of 30 cm between plants and 45 cm between the rows of plants; the procedure was repeated for the crops receiving SI. The average weekly yields were computed for both crops for each season comprised of 14 weeks. The average weekly yields were subjected to Analysis of Variance (ANOVA) to determine whether the average yields from the rain-fed and supplemental irrigated crops were statistically different. This was done with MS Excel 2016 spread sheets by setting a statistical level of significance of 5%. The F value was 17.94 higher than the critical value of 4.01 while the P-value of 9×10 -5 was lower than the 5% level of confidence meaning that there was a significant difference in the yield means of the rain-fed and SI crops. The total rain-fed crop yields for the period was 147.0 Kgs and that of the one under SI was 238 Kgs, an increase of about 62%. Therefore, supplemental irrigation can be adopted in the areas where rainfall trends are declining to increase the crop yields when all other factors remain constant for farmers -to increase resilience.
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