Leaf Harvesting Initiation Time and Frequency Affect Biomass Partitioning and Yield of Cowpea

Abstract

Production of cowpea [Vigna unguiculata (L.) Walp.] leaves as vegetables is the primary goal of many producers. Little is known about how leaf harvesting practices affect N2 fixation and leaf and grain yields. Better information would help optimize overall production of leaves and grain. The objective of this study was to establish an optimal time from crop emergence when harvesting of leaves can be initiated and a frequency of leaf harvesting that would give good vegetable leaf yield without compromising grain yield and N2 fixation. Two cowpea cultivars, Kathoka and Ex‐Luanda were used. Leaf harvesting initiation (LHI) was at 2, 4, or 5 wk after emergence (WAE). Leaf harvesting frequency was at 7‐ or 14‐d intervals. Kathoka produced higher total leaf weight than Ex‐Luanda, while Ex‐Luanda produced more grain yield and nodule weight than Kathoka. Initiating leaf harvesting at 2 WAE gave higher leaf yield but lower grain yield and nodule weight. Initiating leaf harvesting at 5 WAE gave very low leaf yields but high grain yield, as might be expected. Optimum LHI was at 4 WAE and provided adequate leaf yield with acceptable grain yield and nodule weight. Weekly leaf harvesting gave higher leaf yield but lower grain yield and nodule weight than biweekly leaf harvesting. Control plants had the highest grain yield and nodule weight. These data show that producers could potentially optimize production of leaf and grain according to their goals.

Yields and protein content of two cowpea varieties grown under different production practices in Limpopo province, South Africa

“…Neither cropping systems nor cowpea leaf pruning during the vegetative stage had significant effect on the protein content of cowpea green pods. This agrees with similar findings by Saidi et al (2007) who reported that harvesting leaves from cowpea plant at 5 or 7 weeks after planting does not affect leaf, green pod and stem weight and nutrient content. This indicates that Pan 311 green pods could serve as a relatively cheaper and closer substitute for green peas given the fact that cowpea is more adapted, vigorous and easier to cultivate.…”

“…This agrees with similar findings by Muhammad et al (2006) who reported that cowpea in sole plots more crude protein were obtained than in the intercropped plots. This also agrees with findings by Saidi et al (2007) who reported that in a maize-cowpea intercropping system, in the absence of applied P, maize becomes more competitive than cowpea in the initial stages. Significantly (P < 0.05) higher leaf protein content was obtained in 2006/07 than in 2005/06 possibly due to more favorable climate particularly rainfall and better irrigation or due to the residual effect of soil nutrients from previous growing season occasioned by nitrogen fixation.…”

Performances of elite amaranth genotypes in grain and leaf yields in Northern Tanzania

“…Leaf harvesting/defoliation limit the production of exportable sugars which are required as a resource for meristematic activity and for the growth of sink organs, mainly the grain in this case. Saidi et al (2007) reported the highest grain loss in cowpea when leaf harvesting frequency was as per appearance. In the present study, however, some genotypes (RVI00007 and RVI00021) gave higher grain yields in leaf harvested experiment than under leaf not harvested experiment.…”

Morpho-agronomic characteristics of cowpea under different environments and planting densities

“…This inverse relationship also suggests a smaller leaf area per plant, which, according to Saidi et al (2007), affects production and biomass partitioning, as well as grain production per plant and area. According to Taiz et al (2015), the ability to produce dry matter from a crop under satisfactory conditions of water and nutrients will ultimately depend on solar radiation use efficiency, considering that only 5% of incident radiation is converted into carbohydrates by the leaf.…”