ISSN:
1432-1319
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary Cowpea (Vigna unguiculata L.), grown widely under both irrigated and dryland conditions, is well adapted to drought and high temperature and is moderately salt tolerant. Data on photosynthetic response and regulation of water relations in cowpea under salinity stress is lacking. Therefore, in conjunction with a field plot experiment to establish the leaching requirement of cowpea, measurements were made of carbon dioxide assimilation rates (A) by 14CO2 uptake, leaf conductances to H2O (g1) by tritum uptake, and to CO2 (g′), and leaf total water potential (ψt 1) and osmotic potential (ψπ 1). Cowpeas, grown in field plots containing Pachappa fine sandy loam (mixed, thermic, Mollic Haploxeraff), were irrigated daily with saline water (1,350 mg 1−1 total salt concentration) to achieve leaching fractions of 0.17, 0.13, 0.09, 0.07, and 0.02. Cowpea maintained high leaf water potentials, high rates of CO2 assimilation and high leaf conductances under moderately saline conditions (high leaching). Values of ψt 1 and ψπ 1 for high leaching were consistently 50 to 200 J kg−1 higher than for low leaching throughout the day. Calculating ψπ 1 at full leaf turgor eliminated diurnal variation in ψπ 1. As leaching decreased, however, A, g1, and g′, decreased significantly. About 45% of the 1°C assimilated by the leaf was incorporated rapidly into ethanol insoluble compounds. The relationship between A and g1 for cowpea was similar to that reported for other crops.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00344073
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