Effect of Indoleacetic Acid and Zinc Sulphate Application on Growth and Some Physiological Parameters of Cowpea (Vigna sinensis Savi) Plants

Abstract

This study was conducted in Koya city, Iraq on cowpea (Vigna sinensis Savi) plants California black eye variety by factorial experiment including the effects of foliar spraying of Zinc Sulphate ZnSO₄.7H₂O (Z^S) or the plant growth regulator Indoleacetic Acid C₁₀H₉NO₂ (I^AA). Analysis of data revealed that Z^S and I^AA application affects significantly on the studied traits. 100 ppm of I^AA increased significantly the leaves content of each of chlorophylls a, b, and total, although it decreased the content of total carotenoids. The results showed that the leaf area significantly increased by increasing the amount of Z^S to 2.0 g/L compare with other treatments except 1.0 g/L Z^S application. Foliar application of I^AA increased significantly the dry matter percent of shoots and roots as well as the number of nodules per plant. It has been found that leaves content of zinc is related to the concentration of Z^S applied significantly compared to the control and I^AA treatments, however, the application of I^AA caused to decrease K and Zn contents in leaf of the plants compared to other treatments. Finally, based on the results the best ratio of I^AA for increased stomata number on the abaxial and adaxial leaves surfaces was 75 ppm.