Abstract

The study was aimed to modeling of the individual leaf area and dry weight of oregano (origanum onites L.) using leaf length, leaf width and SPAD value. Non-destructive approach of modeling can be very useful for plant growth estimation. To predict individual leaf area and dry weight of oregano, models were developed using leaf length, leaf width, SPAD value, and different combinations of these variables. Eight regression equations, commonly used for developing growth models, were compared for accuracy and adaptability. The two nonlinear models developed were as follows: individual leaf area LA = 0.104 + 0.363W +0.380L² – 0.028W² (R² = 0.973) and dry weight DW = 0.0018 + 0.00102WS + 3.45E^-4 LWS (R² = 0.928), where L is the leaf length, W the leaf width, S the SPAD value, and LWS = L x W x S. For validation of the model, estimated values for individual leaf area and dry weight showed strong agreement with the measured values, respectively. Leaf dry weight, especially, was estimated with a higher degree of accuracy through the use of a SPAD value, as well as leaf length and width. Therefore, it is concluded that models presented herein may be useful for the estimation of the individual leaf area and dry weight of oregano with a high degree of accuracy.

Key words: Oregano, modeling, SPAD value, leaf length, leaf width