Competition for energy and water in sorghum (sorghum bicolor(L.)Moench) - cowpea (Vigna unguiculata(L.) Walp) intercropping systems of West Africa /
Cereal-legume intercropping is the most popular cropping system in sub-Saharan Africa. However, little is known regarding the dynamics of light and water use in these systems. A field study was conducted in two phases to determine how sorghum (Sorghum bicolor (L.) Moench) and cowpea (Vigna unguicu...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739363801&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Cereal-legume intercropping is the most popular cropping system in sub-Saharan Africa. However, little is known regarding the dynamics of light and water use in these systems. A field study was conducted in two phases to determine how sorghum (Sorghum bicolor (L.) Moench) and cowpea (Vigna unguiculata (L.) Walp) compete for energy and water in an intercrop. In the first phase, at Stephenville, TX in 1993, the surface energy balance and latent heat flux of the soil, sorghum and cowpea were investigated in a sorghum-cowpea intercrop planted at low densities (35 000 plants ha E -1) to simulate West African cropping systems in the Sahel. In the second phase, conducted at Cinzana, Mali in 1994, competition for photosynthetically active radiation (PAR) and water was examined in several sorghum-cowpea intercropping patterns. During the hot, dry atmospheric conditions at Stephenville in 1993, sensible and soil heat flux accounted for 40% of net radiation in the sparse intercrop (LAI = 0.89). Latent heat flux at the field level was relatively low (60% of net radiation), whereas sap flow rates of individual plants were high (> 200 g h-1). Cowpea canopy temperature was often > 40 'C due to sensible heat flux and longwave radiation from the soil surface. Rainfall was unusually high (850 mm) in Mali in 1994. The 4 m tall sorghum cultivar CSM 219E intercepted 70% of incoming PAR when LAI reached 2.0. Cumulative seasonal PAR received by intercropped cowpea was 60 to 66% that of the unshaded monocrop. Shading significantly reduced LAI, dry matter and seed yield (37 kg ha E-1') of intercropped cowpea compared to sole cowpea (300 kg ha-'). Sorghum grain yield was not significantly affected by intercropping. Volumetric water content was significantly greater in cowpea ridges than sorghum ridges as shading increased, most likely due to reduced evaporation (shading) and transpiration (decrease in cowpea LAI). Land Equivalent Ratios were < 1.0 for all intercropping treatments due to poor cowpea performance in the intercrop. This study indicates that soil, cowpea and sorghum microclimate are interdependent. Also, competition for light may severely depress legume growth and yield in intercropping systems that use tall cereal varieties. |
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| Item Description: | Vita. "Major Subject: Soil Science". |
| Physical Description: | xi, 96 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 87-95. |