Hedgerow Pruning Effects on Light Interception, Water Relations and Yield in Alley-Cropped Maize

Abstract

In alley cropping, trees and crops compete for light, nutrients, and water. However, there is little information on how hedgerow pruning would impact light interception, water relations, and yield in a maize (Zea mays L.)-mimosa (Albizia julibrissin Durazz) alley-cropping system. Competition between mimosa hedgerows and maize was measured under alley cropping on a compass loam sand in Shorter, AL. Treatments were established in a randomized complete block design and consisted of no pruning or pruning at 30, 30 + 60 and 30 + 90 days after maize planting (DAP) and at 5 cm and 50 cm pruning heights. To minimize competition for nutrients, 189 kg N ha−1, 9 kg P ha−1, and 73 kg K ha−1 were applied. Reduction in photosynthetically active radiation (PAR) was assessed periodically. Water status in maize was assessed using a steady state porometer to measure maize leaf stomatal conductance and transpiration rate. PAR was lower in maize rows closest to hedgerows (ROW1) than in second maize rows from hedgerows (ROW2) especially after 60 DAP. After the 90 DAP pruning, 30 + 90 DAP pruning treatment gave significantly lower stomatal conductance (CD) and transpiration rate (TR) in maize leaves than did 30 DAP or 30 + 60 DAP treatments. ROW1 had high CD and TR, which suggests greater water loss that might reduce final yields. Pruning increased PAR, maize grain and stover yields compared to no-pruning plots. Pruning twice gave higher grain and stover yields than did no-pruning controls. Pruning at 5 cm height gave higher maize yield than pruning at 50 cm. On average, ROW1 had 24% lower yield than did ROW2. Interaction of treatment by row was highly significant. Yield in ROW1 was more affected by pruning treatments than in ROW2. After 90 DAP, 30 + 90 DAP pruning treatment had lowest shade, followed by pruning treatment 30 + 60 DAP at 5 cm height. Pruning at 90 DAP and pruning at 5 cm height reduced competition for water and light. Hedgerow pruning can increase light interception and reduce water stress in the maize crop.