Using models for estimation of leaf area index in Cucurbita pepo L.

In order to find plant growth characteristic relationships with leaf area index in Pumpkin (Cucurbita pepo L.), an experiment was conducted based on randomized complete block design with three replications. Three planting dates (Apr. 20, May 21 and Jun. 21) performed at the research field of Abooreihan Campus, the University of Tehran, Pakdasht, Tehran, Iran, in 2009–2010 cropping season. Sampling was performed during the whole growing season and leaf area (LA), leaf no. per plant, leaf dry weight (LDW), leaf fresh weight (LFW), node no. per main stem and plant height, were measured. The aim of this study was to collect and evaluate nonlinear regression models in the plant growth characteristic studies (exponential, Gaussian, linear, quadratic, symmetric, sigmoid). Root Mean Square Error (RMSE), the standard error of the estimate (SE) and coefficient of determination (R2) were used to find the appropriate model(s). The result showed that, the linear model predicted significant relationships between LAI and LA (R2 = 90), LAI and leaf no. per plant (R2 = 90), LAI and node no. per main stem (R2 = 90), LAI and LDW (R2 = 98) and LAI and LFW (R2 = 98). These result showed that the linear model can be used for estimation of LAI Pumpkin, especially where there is no LAI-meter available. Keywords: Pumpkin, Allometric relationships, Leaf area, Vegetative characteristics, Linear mode