Influence of High Temperature on Morphological Characters, Biomass Allocation, and Yield Components in Snap Bean (Phaseolus vulgaris L.)

High temperature in summer is a major limiting factor for the growth of snap bean in the subtropical islands of Okinawa, Japan. The effect of temperature on biomass production, yield components, and morphological characters were studied in five snap-bean cultivars and strains in the phytotron. Plants were initially grown at 24/20ºC (day/night temperature, 12/12hr) and transferred to 24/20ºC, 27/23ºC (control) or 30/26ºC at the onset of flowering (34 days after sowing). High temperature (30/26ºC) increased single pod weight and the number of flowers and branches, but reduced the number of pods/plant, pod set ratio, and plant weight. ‘Haibushi’, a heat-tolerant cultivar, had higher pod weight/plant, number of pods/plant, pod weight/pod, pod set ratio, number of branches, and rate of biomass allocation to pods, but lower rates of biomass allocation to leaves, stems, and roots than ‘Kentucky Wonder’, a heat-sensitive cultivar, in all temperature regimes. The number of flowers, biomass, and accumulative temperature affected both the yield components (number of pods/plant, single pod weight) antithetically. The yield components were estimated by a stepwise multiple regression analysis. The number of pods/plant was estimated from the number of flowers, leaf weight, pod set ratio per branch, and plant weight with a reasonable precision (R2=0.78). Single pod weight was determined (R2=0.69) from pod set ratio, number of branches, root weight, and accumulative temperature. The results indicated that higher biomass allocation to pods and higher pod set in branches, which were observed in heat-tolerant cultivars at all temperature regimes, were most effective for the estimation of heat tolerance in snap bean

Assessing Drought Tolerance of Snap Bean (Phaseolus Vulgaris) From Genotypic Differences In Leaf Water Relations,Shoot Growth and Photosynthetic Parameters

The Leaf Water Relations, Photosynthetic Parameters and Shoot Growth of Five Snap Bean Cultivars Were Assessed During The Drought Period To Determine Their Role In Alleviating Plant Water Deficit Imposed By Withholding Irrigation At Flowering. Soil Water Content of Irrigated Plants Was 18-20% While That of Unirrigated Plants Was 6-10% At 60 Days After Seeding (Das). Leaf Water Potential Was Approximately 0.15Mpa Lower and Relative Water Content Was Approximately 5% Lower In Unirrigated Plants Than In Irrigated Plants At 57 Das. Unirrigated Plants Had A Lower Stomatal Conductance (Gs) and Intercellular Co2 Concentration (Ci). Reduced Leaf Water Potential and Relative Water Content Were Associated With A Decreased Stem Elongation Rate. Plants With A Lower Stem Elongation Rate Had A Higher Specific Leaf Weight and Succulence Index (Suci). Significant Differences Among Five Cultivars of Snap Bean Were Found For All Parameters Measured. Decreased Leaf Water Potential and Stem Elongation Rate Resulting From Drought Participated In Preserving Relative Water Content and Improving Specific Leaf Weight and Suci. Maintenance of Higher Relative Water Content Increased Gs and Ci. Cultivars That Maintained A High Relative Water Content When Leaf Water Potential and Stem Elongation Rate Were Decreased Markedly, Were More Tolerant To Drought Than Those Which A Reduced Relative Water Content and The Leaf Water Potential and Stem Elongation Rate Were Only Slightly Lowered. Reduced Yield (Pods Per Plant and Seed Biomass) Resulting From Drought Was Associated With Reduced Relative Water Content

Disadoption of Improved Agronomic practices in Cowpea and Maize at Ejura-Sekyeredumase and Atebubu-Amantin Districts in Ghana

The improved cowpea and maize production methods developed in Ghana with the help of farmers are fundamental to increasing cowpea and maize productivity. Improved agronomic practices in cowpea and maize production believed to increase yield are row planting, the use of cover crops and the use of poultry manure. However, the practices are gradually losing their importance in cowpea and maize production. The paper therefore explores the extent to which various factors affect the disadoption of improved agronomic practices and reasons behind disadoption. Multistage sampling techniques were used to select hundred farmers from two cowpea and maize producing areas. Results revealed adoption of cover crops, row planting, poultry manure dropped from 13% to 6%, 99% to 53% and 77% to 10%, respectively. Financial constraint, difficulty in use, time and labour intensity were reasons for disadoption. Empirical results revealed that number of years in education, gender of farm household head, household size, access to extension and hired labour influenced disadoption of improved agronomic practices. Access to production inputs and continuous supply of information are important for farmers’ continuous use of improved agricultural technologies