Plant growth patterns in a tripartite strip relay intercrop are shaped by asymmetric aboveground competition

Abstract

Intercropping is a promising model for ecological intensification of modern agriculture. Little information is available on how species growth patterns are affected by size-asymmetric above-and belowground competitive interactions, especially in intercrops with more than two species. We studied plant growth and competitive interactions in a novel intercropping system with three species: wheat, watermelon and maize. Wheat and maize are grown sequentially (as a double cropping system) in narrow strips while watermelon is grown between the cereal strips, with partial overlap in growing period with the two cereals. Growth patterns were monitored over two years and described with logistic growth curves. Root barriers were used to study the effect of belowground interactions. Wheat produced 31% greater yield per plant in the intercrop than in the sole crop but 24% lower yield per unit total (inter)crop area. Wheat yield increase per plant was associated with faster growth and substantial overyielding in the outer rows of wheat strips. Watermelon did not competitively affect wheat. Watermelon biomass was substantially reduced at the time of wheat harvest. However, compensatory growth after wheat harvest and greater allocation to fruits resulted in a good yield of intercropped watermelon, 92% of monoculture yields, at final harvest. Intercropped maize produced 32% lower grain yield per plant and per unit area than sole maize, as a consequence of later sowing and a changed plant configuration in the intercrop as compared to the sole crop, and competitive effects of watermelon, as shown by comparison with a skip-row maize system without watermelon. Root barriers did not affect yield of any of the species, indicating that aboveground competitive interactions in this case played a more important role in shaping the observed growth responses than belowground interactions. Plant interactions in this tripartite intercrop system are consistent with the hypothesis of size-asymmetric competition for light.

Optimized planting time and co‐growth duration reduce the yield difference between intercropped and sole soybean by enhancing soybean resilience toward size‐asymmetric competition

“…The asymmetric competition is the unequal distributions of available resources between component crops: the crops at the top of a competitive hierarchy can access and obtain more available resources than the one at the bottom (Freckleton & Watkinson, 2001;Weiner, 1990). However, it is unclear how size-asymmetric competition affects the aboveground and belowground interspecific interaction in intercropping (Huang et al, 2017). In MSRI, when soybean emerges, the soybean seedlings come under maize shade and receive fever nutrients, light and water for its growth and development (Feng et al, 2019;Raza, Khalid, Zhang, Feng, et al, 2019).…”

“…The competition among two crop species is closely associated with the supply of resources and allocation (Craine & Dybzinski, 2013;Liu et al, 2016), size of the plants (Park, Benjamin, & Watkinson, 2003), and spatial and temporal arrangements of components (Xie & Kristensen, 2017;Yang, Qing, et al, 2017). Since these factors affect the initial size of the plant, thus, initial plant size advantage mainly causes the competition between two species (Huang et al, 2017;Schwinning & Weiner, 1998).…”

Effect of shading and light recovery on the growth, leaf structure, and photosynthetic performance of soybean in a maize-soybean relay-strip intercropping system

“…For instance, maize-soybean relay-strip intercropping is widely adopted in southwestern parts of China, where maize is sown in April and harvested in August, while soybean is sown in June and harvested in October[ 2 ]. The advantages of this system include the effective and efficient utilization of farmland resources[ 3 ] and low incidences of diseases, pests, and weed damage[ 4 , 5 ]. This system also increases the economic benefits compared with that of sole cropping of soybean[ 6 , 7 ].…”

“…In past reports it has been reported that the shading condition significantly changed the morphological characteristics, biomass, and physiological response of soybean seedlings [ 23 , 14 ]. Several studies have also provided insights into the leaf anatomical features of various plants under shading conditions [ 24 , 21 , 4 ].…”

How do cotton light interception and carbohydrate partitioning respond to cropping systems including monoculture, intercropping with wheat, and direct-seeding after wheat?

“…Moreover, double cropping systems are important factors that influence cotton growth and yield components [6]. Owing to the indeterminate growth habit of cotton plants, cotton crops display morphological adaptations to their growth environment, including modifications to their canopy structure in response to planting patterns [7–10]. Morphological adaptations with respect to canopy development, light interception, source-sink relationships and assimilate partitioning are the major determinants of lint yield [11–12].…”