The Effect of Seed Size on Seed Vigor Indices of Different Wheat Cultivars

Abstract Germination and beneficial seedling establishment is affected by different seed vigor indices. In order to study the effect of seed size on seed vigor indices of wheat, a factorial experiment with two factors was conducted in a completely randomized design with four replications at the Agricultural Natural Resources Research Center Lab of Khorasan Razavi. The first factor was thirteen genotypes of wheat in three types of growth, containing winter, facultative and spring and the second factor was seed size in four levels including 3, 2.5, 2 and 1.5 millimeter. Germination percentage, germination rate, shoots and root length, seedling growth rate and shoot:root length ratio characteristics were investigated. Analysis of variance showed that the effect of wheat cultivars and seed size on traits was significant (p≤ 0.01) but interaction effect of seed size and wheat cultivar was significant (p≤ 0.01) only for shoot and root length, seedling growth rate and shoot:root length ratio. The highest and lowest seedling growth rate was (15.85 and 8.23 mg dry weight/germinal seedling) that they were related to 3 and 1.5mm seed size, respectively. According to these observations the most and least percentage and germination rate was related to these seed size treatments. Correlation coefficient of seed size and seedling growth rate was highly significant (r=0.85 p≤ 0.01). Stepwise regression method indicated that the seed size (x1) and shoot length (x2) as independent variables could be described (r2=0.84) seedling growth rate as a dependent variable in y= -5.000955+(5.128078x1)+(0.78494x2) equation. Keywords: Seedling growth rate, Germination rate, Correlation, Regressio