Leaf Area Estimation in Yam Bean ( Pachyrrhizus erosus L.) using Linear Measurement of Leaf Parameters

Abstract

Yam bean is a leguminous minor tuber crop grown in tropical regions for its turnip like edible tuberousroots for its delicacy. The seeds are protein rich and have insecticidal properties. So far, there is noinformation available in this crop for the estimation of leaf area; hence a simple method for leaf areaestimation in yam bean (Pachyrrhizus erosusL.) was developed. In yam bean each leaf had threeleaflets. Measurements on the length, breadth of leaflets of varying size were recorded. There wassignificant positive correlation between length (L) and area (A) (r = 0.889) and; breadth (B) and area(A) (r = 0.927) of leaflet. The factor (F) of relationship between L and A of leaf was 6.129 and thatbetween B and A of leaflet was 5.569. The relation between product of length and breadth (P) and Aof leaflet was also significant (r = 0.749) and the F between P and A was 0.643. The linear regressionequation between L and A, B and A and between P and A were Y = 10.99x . 40.88, Y = 7.147x .14.58 and Y = 0.571x + 5.702 respectively. The coefficient of determination (r2) values between Land A, B and A; and P and A were 0.792, 0.860 and 0.933 respectively. The r2value observedbetween P and A near to 1 (0.933) suggested that the regression equation was good fit. Therefore,using the F value derived from P, the total leaf area of a plant can be calculated by the formula: Totalleaf area = P of a single leaflet (average value of few observations) x 0.64 x 3 x total number of leavesper plant. The coefficient of determination between dry weight of leaflet to area was closer to 1 (r2=0.903) and significant positive correlation coefficient value (r = 0.950) between weight of dry leafletand area suggest that the dry leaf weight method can also be used for calculating leaf area of yambean. The factor (F) derived between weight of dry leaflet and area of leaflet was 0.233. From the Fvalue, the total area of yam bean can be calculated by the formula: Total leaf area = weight of a singledry leaflet (average of few leaflets) x 0.233 x 3 x total number of leaves per plant.