Abstract
Changes in the light environment have an important effect on crop growth and yield. To clarify the effects of intercropping and the application of nitrogen on the yield of wheat and light within the crop canopy, the relationship between light and yield and their response to nitrogen fertilizer were studied. In a 2-year field experiment, the characteristics of growth, light, biomass, and yield of wheat were measured using three cropping arrangements (monocropped wheat, monocropped faba beans, and intercropped wheat/faba beans) and four levels of applied nitrogen, in groups termed N0 (0 kg/ha), N1 (90 kg/ha), N2 (180 kg/ha), and N3 (270 kg/ha). The results demonstrated that the application of nitrogen fertilizer increased wheat plant height, spike leaf length and width, and the number of leaves while significantly decreasing wheat canopy light transmittance (LT) and canopy photosynthetic active radiation transmittance (PART), by 7.5–71.1 and 12.7–75.1%, respectively. There was a significantly increased canopy photosynthetic active radiation interception rate (IPAR) of 7.5–97.8% and an increase in biomass of 9.6–38.4%, of which IPAR, biomass, and yield were highest at the N2 level. Compared with monocropping, intercropping increased parameters of wheat growth to varying degrees. Intercropping decreased LT and PART by 10.8–46.4 and 15.7–58.7%, respectively, but increased IPAR by 0.1–66.0%, wheat biomass and yield by 7.5–17.4 and 27.7–47.2%, respectively. The mean yield of intercropped wheat increased by 35.8% over 2 years, while the mean land equivalent ratio (LER) was 1.36, for which a values greater than 1 indicates that wheat and faba bean intercropping is advantageous. Correlation analysis demonstrated that there was a very significant negative correlation between wheat LT and yield, while simultaneously demonstrating a very significant positive correlation between PART and IPAR with yield, indicating that the efficient interception and utilization of light energy in intercropping was the basis for the higher biomass and yield of wheat. In summary, wheat/faba bean intercropping and the application of nitrogen at 180 kg/ha were effective in increasing wheat yield.
Highlights
Wheat (Triticum aestivum L.) is the second-largest food crop after rice and is widely cultivated and produced around the world
The results demonstrate that the application of nitrogen was beneficial for the growth of wheat, especially at the highest nitrogen (N3) level, while the response of wheat plant height to nitrogen was greater than that of spike leaf length, spike leaf width, or numbers of leaves
The results demonstrate that intercropping increased wheat plant height, leaf number, and spike leaf length, but the advantage of intercropping decreased with increasing levels of nitrogen
Summary
Wheat (Triticum aestivum L.) is the second-largest food crop after rice and is widely cultivated and produced around the world. China is one of the major wheat-producing countries, having an area of cultivation and total yield that ranks first of any country around the globe, and mean yield per unit area ranking tenth (The Food and Agriculture Organization Corporate Statistical Database (FAOSTAT), 2020). It is important that the yield of wheat is carefully considered so that the requirements of humans are fulfilled and their nutritional balance maintained. The rate of interception and efficiency of utilization in a planted crop play major roles in determining the final yield (Wang et al, 2015; Raza et al, 2019; Gong et al, 2020)
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