Effects of Plant Density on the Growth, Reproduction and Survivorship of Cucumbers in Monocultures and Polycultures

Abstract
The growth, reproduction, and survivorship of cucumbers (Cucumis sativus) were studied in experimental plots of 2 densities (low and high) and 2 diversities (cucumber monocultures and polycultures of cucumbers, corn (Zea mays) and broccoli (Brassica oleracea)). Both density and diversity strongly affected plant growth and reproduction, but diversity effects were stronger and more consistent over time. Interactive effects between density and diversity were significant for growth only. Plants in monocultures had greater leaf areas, vine lengths, growth rates, numbers of flowers, and yields than did plants in polycultures, and plants at low density had greater values for most of these parameters than did plants at high density. Leaf area distributions were positively skewed throughout the season in high density polycultures only, but also became positively skewed in high density monocultures towards the end of the season. Survivorship was affected by diversity only; plants had shorter longevities in monocultures than in polycultures. Cucumber plants displayed a plastic response to density and diversity. For any given leaf area or number of flowers, per plant yields were significantly greater in monocultures than in polycultures.