Area and Dry Mass Estimation of Cashew (Anacardium occidentale) Leaves: Effect of Tree Position within a Plantation around Parakou, Benin

Accurate and non-destructive methods to determine individual leaf areas and dry mass of plants are very important. Since they stand as key parameters linked to plant production and are used in functional–structural plant models to simulate plant growth. This paper describes an investigation of the variation in cashew leaf dimensions at different sites within a plantation with the aim of developing a model for calculating leaf area and dry mass. Five location (South, Central, North, East and West) were considered in an eight years old cashew plantation, with rectangular plot and with an area of 3.5 ha. Two trees were selected randomly by location. Their crown was divided vertically into three zones. Within each zone, 60 leaves were collected randomly on different categories of the tree axis. The length, width, area, and the dry mass of each leaf were measured. The longest leaves were obtained in the North, Center and South of the plantation (15.27 cm). The tree leaves located in the South of plantation were the largest (9.6 cm) and had the largest areas (109.1 cm²). The largest quantities of dry mass were obtained from the leaves of the trees located in the South and in the East of the plantation (1.35 g per leaf). The best models according to adjustment and prediction qualities were in all cases stated as follows: Sλ= aln(LW) + b for leaf area and mλ= aln(LW) + b for dry mass. The results indicated an important variation in leaf size and dry mass according to a tree location in the plantation. Therefore, it is important to take into account this variability in the sample constitution when trying to estimate leaf area and dry mass.