Speaker
Description
Introduction
Strip intercropping is a form of species mixture where the companion species are grown in narrow strips to allow species-specific management. Strong interspecific interactions occur between plants in the borders of these strips, whereas plants in the middle of the strips mostly compete for resources with conspecifics (Zhu et al., 2015). Light capture differs greatly between inner and outer rows of strips and is probably a driving force for yield effects in strip intercropping. However, light capture per row is hard to quantify. Here we use a ray tracing model to quantify how intercropping affects light capture in different rows of a strip.
Materials and methods
We conducted a modelling study, based on a field experiment performed in 2019 in the Netherlands (Wang et al., 2023). The experiment involved six bi-specific strip intercrops including maize (Zea mays L.), wheat (Triticum aestivum L.), faba bean (Vicia faba L.), and pea (Pisum sativum L.). Maize was sown five weeks later than the other three species. Each species was grown in 1.5 m-wide strips with three rows for maize, and six rows for the other three species. We reimplemented a ray tracing model (Gijzen and Goudriaan, 1989; Wang et al., 2017), using measured plant height and leaf area index as model inputs, to estimate light capture per row in intercrops and monocrops.
Results
In the modelled relay intercrops, the early-sown species all captured more light in the intercrop border rows than in the inner rows and monocrops due to the initial absence of neighbouring maize (Fig. 1). Inner rows of the early-sown species did not show such light capture advantages. Compared to monocrop maize, border row maize in intercrops only captured more light when growing with wheat and pea, but not with faba bean because faba bean was taller than wheat and pea, and caused substantial early shading on maize, which was only partially compensated after faba bean harvest. Inner row maize captured more light in all intercrops. The simultaneous intercrops without maize did not show complementarity for light capture, and any (light capture) advantage for one species was offset by a disadvantage for the other species. Faba bean substantially reduced light capture of wheat and pea in all intercrop rows, whereas the faba bean itself only obtained a substantial increase in light capture in the border rows, and only a slight increase in the inner rows.
Discussion
This study indicates that relay intercrops, which exhibit temporal complementarity, are more efficient in capturing light compared to simultaneous intercrops, where species coexist for most of the season. These results align with the light capture advantages found in maize/wheat relay strip intercropping in the Netherlands (Gou et al., 2017; Zhu et al., 2015), suggesting that the positive effects of temporal complementarity in light capture apply to both cereal/cereal and cereal/legume combinations. The early-sown species benefited from border rows capturing more light in the early season. The late-sown maize increased light capture in both border and inner rows after the early companions had been harvested, with significant decreases in border rows with tall-statured companion species, highlighting the importance of early season competition. Use of the ray tracing model allows analysing species or variety combinations, strip widths and sowing dates are suitable for light-capture-efficient intercropping.
References
Gijzen, H., Goudriaan, J., 1989. A flexible and explanatory model of light distribution and photosynthesis in row crops. Agric For Meteorol 48, 1–20.
Gou, F., van Ittersum, M.K., Simon, E., Leffelaar, P.A., van der Putten, P.E.L., Zhang, L., van der Werf, W., 2017. Intercropping wheat and maize increases total radiation interception and wheat RUE but lowers maize RUE. European Journal of Agronomy 84, 125–139.
Wang, Z., Dong, B., Stomph, T.J., Evers, J.B., L. van der Putten, P.E., Ma, H., Missale, R., van der Werf, W., 2023. Temporal complementarity drives species combinability in strip intercropping in the Netherlands. Field Crops Res 291, 108757.
Wang, Z., Zhao, X., Wu, P., Gao, Y., Yang, Q., Shen, Y., 2017. Border row effects on light interception in wheat/maize strip intercropping systems. Field Crops Res 214, 1–13.
Zhu, J., van der Werf, W., Anten, N.P.R., Vos, J., Evers, J.B., 2015. The contribution of phenotypic plasticity to complementary light capture in plant mixtures. New Phytologist 207, 1213–1222.
| Keywords | Europe; Strip intercropping; Light capture; Modelling; Border row effects |
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