Root Diversity among Peanut Genotypes1,2

Abstract

Improved drought tolerance of some crops has been associated with extensive root systems. Since peanut (Arachis hypogaea L.) is grown in many arid and semiarid regions, this study was done to determine if peanut genotypes differed in extent of root growth (volume and dry weight). A method to estimate root growth potential of peanut by measuring root volumes was developed and used to make comparisons among peanut genotypes. Plants were grown in the greenhouse for 46 to 49 days in PVC tubes (10.2 cm i.d, and 76.2 cm in length) containing fritted clay. Plants were fertilized twice weekly with 200 ml of modified Hoagland solution and watered twice daily. Comparisons of growth were made among and within virginia, spanish, and valencia botanical type peanut. Genotypes differed in both root (volume and dry weight) and shoot (height, dry weight, leaf area, and leaf number) characteristics. Root volume and dry weight were highly correlated among the entries tested. Shoot dry weight, leaf area, and number of leaves were significantly correlated in most tests. Root dry weight and volume were positively correlated with shoot dry weight, leaf area, and number of leaves, but not necessarily with all of these parameters in every test. The data indicate strong coordination between aerial and subterranean growth and considerable diversity in root volume. The differences among entries in this limited sample of peanut germplasm suggest selections for more extensive rooting traits is feasible for this crop and may prove useful for developing more drought tolerant peanut cultivars.