Browsing by Author "Mwamlima, Louis Hortensius"

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Effects of Soil Moisture Regimes, Planting Density and Intercropping on Growth and Yield of Selected Soybean Cultivars in Kenya
(Egerton University, 2019-11) Mwamlima, Louis Hortensius
Soybean [Glycine max (L) Merrill] yields in Kenya range from 445-1200 kg ha-1 against potential yields of 3500 kg ha-1. The low yields are attributed to soil moisture stress and use of poor agronomic practices. The objectives of the study were to determine effect of soil moisture regimes on CO2 assimilation, growth and yield of selected soybean cultivars; to determine effect of planting density on yield and yield components of soybean and to determine effect of soybean and maize intercropping on stomata conductance, shoot characteristics and yield of soybean. A greenhouse moisture stress study was laid out in a randomized complete block design (RCBD) in a 6 by 4 factorial treatment arrangement and was replicated three times. Soil moisture regimes (80, 60, 40 and 20% of field capacity) and cultivars (Gazelle, Nyala, EAI 3600, DPSB 8, Hill and DPSB 19) were first and second factors, respectively. Field moisture stress study used RCBD in a split plot arrangement with three replicates. Moisture regimes (100, 75, 50 and 25% of soybean crop water requirement) and cultivars (as in experiment 1) were main plot and sub plot factors, respectively. The third experiment evaluated effects of planting density on yield and yield components of soybean using a 5 by 2 factorial arrangement in RCBD. Planting densities (10, 12, 20, 40 and 80 plants per m2) and cultivars (EAI 3600 and DPSB 19) were first and second factors respectively. The fourth experiment determined effect of soybean and maize intercropping on stomata conductance, shoot characteristics and yield of soybean. The experiment was conducted using RCBD with 3 replicates. Soil moisture stress significantly (p < 0.001) reduced soybean shoot and root growth of all tested cultivars. Leaf relative water content, stomata conductance, photosynthetic rate and sub-stomatal CO2 levels significantly (p < 0.001) declined with increasing soil moisture stress. Cultivar DPSB 19 had higher stomata conductance but reduced transpiration rate at lower soil moisture levels. Highest number of nodules per plant were attained at 10 plants m-2 which was 34.76% more than number of nodules obtained at 80 plants m-2. Soil moisture depletion at 80 plants m-2 was 15.22% higher than at the lowest plant population of 10 plants m-2. Intercropping maize and soybean significantly (p < 0.01) reduced soybean leaf area, IPAR, stomatal conductance and photosynthetic rate. Intercropping reduced soybean yield by 80.72% though 1M:1S row pattern gave relatively higher soybean yields than other intercropping patterns. Soybean cultivar DPSB 19 is recommended for production under soil moisture stress conditions while planting soybean at 20 plants m-2 is recommended for optimum soybean yields. Planting maize and soybean in 1M:1S row pattern should be used when intercropping the two crops.
Leaf Gas Exchange and Root Nodulation Respond to Planting Density in Soybean [Glycine Max (L) Merrill]
(Hindawi, 2020-01) Mwamlima, Louis Hortensius; Ouma, Josephine Pamela; Cheruiyot, Erick Kimutai
Planting density influences structural characteristics and affects mineral nutrient acquisition, irradiance and photosynthesis amongst plants. An experiment was conducted to determine the effect of planting density on leaf gas exchange and nodulation of soybean (Glycine max (L) Merrill). e experiment was conducted as a randomized complete block design (RCBD) in a 5 by 2 factorial treatment arrangement and was replicated three times. Planting density (10, 12, 20, 40, and 80 plants m−2) and soybean varieties (EAI 3600 and DPSB 19) were first and second factors, respectively. Collected data were subjected to analysis of variance in GENSTAT. Significantly different treatment means were separated using Tukey’s honestly significant difference test at 0.05 significance level. Higher planting density significantly increased ( < 0.001) interception of photosynthetically active radiation. Increasing number of plants per unit area significantly ( < 0.001) reduced root nodulation, stomata conductance, sub-stomatal CO2 concentration, photosynthetic and transpiration rates. Total chlorophyll content was not responsive to planting density though concentration of chlorophyll “a” content was significantly ( < 0.005) higher at lower plant density than at higher plant density. Soil moisture status increased with reduction in plant density. Indeterminate variety DPSB 19 had higher rates of stomata conductance, photosynthesis and sub-stomatal CO2 concentration compared to determinate variety EAI 3600.
Physiological Response of Soybean [Glycine Max (L) Merrill] to Soil Moisture Stress
(African Journal of Agricultural Research, 2019-04) Mwamlima, Louis Hortensius; Ouma, Josephine Pamela; Cheruiyot, Erick Kimutai
This study was done to determine the effects of varying soil moisture regimes on CO2 assimilation of soybean [Glycine max (L.) Merrill] in pots under greenhouse conditions during 2017 and 2018 cropping seasons. The experiment was conducted as a Randomized Complete Block Design (RCBD) in a 4 x 6 factorial treatment arrangement and replicated 3 times. Soil moisture regimes (80, 60, 40 and 20% of field capacity) and cultivars (Gazelle, Nyala, EAI 3600, DPSB 8, Hill and DPSB 19) were first and second factors, respectively. Collected data were subjected to Analysis of Variance (ANOVA) using Linear Mixed Model in GENSTAT. Significantly different treatment means were separated using Tukey’s test at 0.05 significance level. Leaf relative water content, stomata conductance, photosynthesis rate and substomatal CO2 concentrations significantly (P < 0.001) declined with increasing soil moisture stress. Total leaf chlorophyll content increased (P < 0.001) with increased soil moisture stress. Cultivars DPSB 19 and DPSB 8 had relatively higher leaf relative water content and stomata conductance at reduced soil moisture regime at 20% moisture from field capacity indicating moisture stress tolerance potential of the cultivars. Key words: Flowering stage, podding stage, seasons, soil moisture regimes, soybean cultivars.