Growth and Metabolic Changes of Cowpea Plants as Affected by Water Deficiency and Indole-3-Yl-Acetic Acid

Cowpea plants ( Vigna sinensis Savi.) were grown in pots for two successive years. These plants were daily maintained water holding capacities (15, 25, 45, 65 %).
The foliage of plants grown at every level of soil moisture was sprayed till dripping with IAA solutions (0, 10, 50, 100 mg/l) three times after 3, 6 and 9 weeks from sowing. Samples were taken at the two physiological stages before flowering and during flowering for growth measurements and determinations of nitrogen fractions.
Water shortage led to retardation of stem length, number of internodes, number of leaves and dry weight shoots. IAA increasing the same parameters only when applied at concentrations of 10 and 50mg/1 at moisture level 65 %, 45 % and 25 % of W.H.C.
Water stress decreased total-N and protein-N contents of cowpea shoots. On the other hand total soluble- N content was increased under the same conditions. IAA increased total-N and protein-N content of cowpea shoots. Meanwhile, the same growth regulator decreased total soluble-N when applied at 45% 25 % and 15 % W.H.C. levels.     

Combined Effect of Soil Water Availability and Growth Substances on Some Aspects of Chemical Composition of Cowpea Plants

Cowpea plant ( Vigna sinensis Savi) were grown in pots for two successive years. These plants were daily maintained at water holding capacities (15, 25, 45 and 65 %). The foliage of plants grown at every level of soil moisture was sprayed till dripping with either IAA solutions 0, 10, 50 and 100 mg/1 or kinetin solutions 0, 10, 20 and 40 mg/1 three times after 3, 6 and 9 weeks from sowing. Samples were taken at two physiological stages before flowering and during flowering for determination of photosynthetic pigments and carbohydrate fractions.
Water stress decreased all photosynthetic pigments (chlorophyll "a", chlorophyll "b" and carotenoids). Meanwhile, it increased the ratios of "a/b" and (a + b)/carotenoids. IAA and kinetin at all concentrations increased photosynthetic pigments. In addition, the same treatments led to decrease in the ratios of "a/b" and a + b/carotenoids.
Total carbohydrate content was decreased by decreasing soil moisture content. Meanwhile, reducing sugars as well as sucrose contents were increased. IAA and kinetin increased total carbohydrate, reducing sugars and sucrose of cowpea shoots comparing with respective controls.     

Effects of Water Deficiency and Kinetin on Growth and Nitrogen Metabolism of Cowpea Plants

Cowpea plants ( Vigna sinensis Savi.) were grown in pots for two successive years. These plants were daily maintained water holding capacities (15, 25, 45, 65 %).
The foliage of plants grown at every level of soil moisture was sprayed till dripping with kinetin solutions (0, 10, 20, 40 mg/1) three times after, 3, 6 and 9 weeks from sowing. Samples were taken at the two physiological stages before flowering and during flowering for growth measurements and determination of nitrogen fractions.
Water shortage led to retardation of stem length, number of internodes, number of leaves and dry weight of shoots. Kinetin reduced stem length of cowpea shoots. On the other hand, it exhibited stimulative effect when applied at concentrations 10 and 20 mg/1 on number of internodes, and dry weight of shoots.
Water stress decreased total–N and protein–N contents of cowpea shoots. On the other hand total soluble–N content was increased under the same conditions. Kinetin increased total–N and protein–N contents of cowpea shoots. Meanwhile, the same growth regulator decreased total soluble–N when applied at 45 %, 25 % and 15 % W.H.C. levels.