Prediction of Plant Height by Allometric Relationships in Field-grown Wheat

Crop simulation models use allometric relationships to predict plant height from vegetative characteristics. The objective of this study was to find relationships between plant height (PH) and number of leaves on main stem (NLMS), stem dry weight (SDW) (g plant(-1)) and total vegetative components (leaves and stems) dry weight (TVDW) (g plant(-1)) in wheat (Triticum aestivum L.). For this purpose, an experiment was conducted using seven wheat cultivars including two durum wheat cultivars (Arya and Taro) and five bread wheat cultivars (Darya, Kuhdasht, Shiroudi, Tajan and Zagros) under irrigated and rainfed conditions during 2008-2009 at Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. The experimental design was a randomized complete block design with four replications. Sampling was started from beginning of tillering and continued until maturity. A segmented nonlinear regression model was used to describe allometric relationships between PH and the vegetative characteristics. The results showed that there was no significant difference between cultivars and the two conditions for allometric relationships, so one equation was usable for all cultivars under both irrigated and rainfed conditions. Significant relationships were found between PH and NLMS (R-2 = 0.94), SDW (R-2 = 0.95) and TVDW (R-2 = 0.95). These equations can be used for estimation of PH in simulation models of wheat.