Growth analysis of cashew seedlings as affected by nut-size in the nursery

摘要

The use of growth analysis technique in elucidating the physiological factors affecting growth of cashew is limited, which has hitherto created a serious gap in the cultivation of the crop. Three nut-sizes (jumbo ( 16 g), medium (4 ndash; 8 g) and madras ( 2 g)) were subjected to detailed growth analysis technique in a non-shaded nursery in Nigeria. The experiment was in completely randomized design with 4 replicates. Two seedlings were randomly sampled per nut-size per replicate for destructive analysis at 1 monthly interval for the 12-month study period. Total leaf area and dry matter per plant were taken, from which leaf area index (LAI), crop growth rate (CGR), net assimilation rate (NAR) and relative growth rate (RGR) were computed. Results show that leaf area and dry matter of cashew seedlings were linearly related with r2 = 0.9. At 1 Month After Sowing (MAS), seedlings raised from jumbo nut-size had 62.4 and 375 dry matter advantages over seedlings raised from medium and madras nut-sizes respectively. These variations reduced to 1.7 and 26.9 at 12 MAS. Total leaf area followed a similar pattern as the dry matter yield. The LAI of seedlings raised from jumbo nut-size was 91.7 and 66.7 higher than the LAI values of seedlings raised from medium and madras nut-sizes respectively. While mean NAR of cashew seedlings reduces from2.8 g/m2/day at 1 MAS to 1.02 g/m2/day at 12 MAS, the mean CGR increases, reaching peak values at 3, 7, 10 and 12 MAS. Cashew seedlings raised from madras nut-size had highest NAR of 3.88 g/m2/day followed by that of medium and jumbo nut-sizes with 2.9 g/m2/day and 1.66 g/m2/day respectively. The higher size of jumbo nut of cashew is translated into improved dry matter yield with time compared to cashew nuts of lighter sizes.