Objectives Leaf number is closely related to dry matter production, nutrient absorption and yield formation. We studied the effect of foliage removal on the nutrient accumulation and yield of cassava, to achieve high-yield and efficient use of N, P, K nutrition.
Methods A split-split plot experiment was conducted in Jiangxi Province. The main plots were two cassava types (compact and umbrella), subplots were two cassava cultivars for each plant type (SC205 and GR4 for compact type and SC12、SC15 for umbrella type), and the sub-sub plots were the remaining leaf number (9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99 and 108 leaves). The dry matter and N, P, K accumulation in plucked leaves and plants at the matured stage of the crop were analyzed.
Results With the increase of the remaining leaves, the N, P, K accumulation in plucked leaves decreased, while the fresh tuber yield increased significantly, and the total N, P, K accumulation at the matured stage and those throughout whole growth period increased significantly, showing a “single peak” or "double peak". The nutrient accumulation varied among cassava cultivars. N accumulation in compact cultivars was 4.56% lower than that of umbrella type cultivars, while the P and K accumulation of compact cultivars were 10.23% and 10.00% higher than those of umbrella type cultivars. The N, P, K accumulation in mature plant of compact type cultivars were 31.00%, 42.48% and 50.92% higher than those of umbrella type cultivars, respectively. At the matured stage, the cassava with the more leaves had higher N, P, K distribution in tuber and leaves, but lower in stems, while the N, P, K harvest index had a “single peak” or “double peak” pattern. The harvest indexes of N, P, K of compact cultivars were higher than those of umbrella type cultivars with 0.48, 0.63, 0.58 and 0.42, 0.60, 0.55, respectively. With the increase in remaining leaf number, more N, P, K were remained in mature plants. The residual N, P and K percentage points in the mature plant of compact cultivars were 7.33, 5.45 and 4.36 higher than those in umbrella type cultivars, respectively.
Conclusions The more leaves of cassava remained the less the plucked leaf number and the lower of dry matter in them. A high leaf number of cassava plant increased the tuber yield and the N, P, K accumulation at maturity as well as nutrients distribution rate in tuber and leaf. The suitable remaining leaf number was 81–90 pieces at tuberous root expansion stage, which proved beneficial for a high yield, nutrient accumulation and utilization in cassava.
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