Abstract
Intercropping has been seen as an advantageous strategy in sustainable agriculture. Plants however interact with one another both above and below ground with members of the same species (intraspecific) or members of a different species (interspecific) for nutrients, water and light. It is therefore essential to understand these interactions when intercropped. The objective was to examine the above and below ground interactions between onion and lettuce in monocrop and intercrop systems. We examined the various possible interactions (no competition, above ground, below ground, or full) using a full factorial randomized design under greenhouse conditions. Onion yield was highest in intraspecific above ground competition and lowest in below ground and full interspecific competition with lettuce. Dry weight of onions in above ground competition with lettuce was significantly greater than that of the control group. Fresh weight of lettuce leaves were highest in below ground and full interspecific competition treatments. The hectare model and yield results suggest that there is strong below ground competitive effect between onion and lettuce in intercrop. Asymetric interspecific facilitation was found: facilitation by onion led to increased lettuce yield but a negative effect of lettuce on onion yield was observed. Knowledge of competitive interactions between component crops can have several applications in sustainable agricultural as it helps to match the most efficient species under specific conditions.
Highlights
Intercropping is an agricultural technique based on the management of plant interactions to maximize crop yield and involves cultivating two or more crops in the same field within the same growing season [1] [2]
Onion bulbs exposed to intraspecific above ground competition had the highest fresh weight
The lowest yield is predicted when onions are planted in interspecific competition with lettuce (63 kg/ha, Figure 3)
Summary
Intercropping is an agricultural technique based on the management of plant interactions to maximize crop yield and involves cultivating two or more crops in the same field within the same growing season [1] [2]. Competitive interactions between two plants, brought about by a shared requirement for soil nutrients, water or light, can have negative effects on either species by decreasing growth rate, survival, reproduction or yield of one or both plants [5] [6]. Lettuce (Lactuca sativa), for example, is expected to be more competitive in intercrop because it is a fast emerging, tall and broad-leaf plant that is able to obtain a larger share of available light than slower growing and smaller plants like onion [7]. Onion crops (Allium cepa) are known to be a weak competitor because of their initial slow growth rate after planting (juvenile growth), development of shallow fibrous roots and a small above ground canopy, which does not cover the soil [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
