Growth Characters, Yield and Endogenous Hormones of Cowpea Plants in Response to IAA Application

Cowpea plants (Vigna sinensis L.) variety " Cream 7" were grown in pots. The foliage of the plants were sprayed twice at 70 and 80 days from sowing with Indole-3-acetic acid (IAA) solutions of (25, 50 and 100 mg/L) and the control plants were sprayed with distilled water. IAA treatments at the rate of 25 and 50 mg/L increased number of leaves, shoot dry weight and number of produced flowers per plant. Meanwhile 50 and 100 mg IAA significantly decreased the number of flowers abscised from cowpea plant. IAA at 25 and 50 mg/L significantly increased number and weight of pods and seeds per plant. Endogenous IAA, gibberellins and cytokinins increased during flowering and at abscission time, however, ABA content was decreased by all applied concentrations of IAA. Further responses of cowpea plants to IAA applications are discussed.