Mix‐cropping of rice and water mimosa (Neptunia oleracea Lour.) increases rice photosynthetic efficiency, yield, grain quality and soil available nutrients

Abstract

Cereal cultivation with legumes plays an important role in improving biodiversity and productivity. However, there are limited references concerning rice/legume mix-cropping in paddy fields. An aquatic leguminous plant, water mimosa (Neptunia oleracea Lour.), was introduced and a related field experiment of two seasons (early and late seasons in 2019) was carried out to explore the effects of rice/water mimosa mix-cropping on rice growth, yield, grain quality and soil nutrients in the present study. Three treatments - rice monocropping, rice/water mimosa intercropping and mix-cropping - were employed in this study. Results showed that rice grew better with greater height, tiller number, chlorophyll content, actual photosynthetic efficiency [Y(II)], maximum photochemical efficiency (Fv /Fm ) and photochemical quenching coefficient (qP) in the intercropping and mix-cropping treatments. In addition, the intercropping and mix-cropping treatments increased nutrient uptake of nitrogen (N) by11.89-24.42%, phosphorous (P) by 17.75-36.61% and potassium (K) by 19.22-47.44%, and rice yield by 19.9% and 21.8%. Conversely, the non-photochemical quenching coefficient (NPQ), chalkiness degree and chalky rate of rice were lower in the intercropping and mix-cropping treatments relative to those in the monocropping treatments. Notably, soil alkali-hydrolysable N (AN), available P (AP) and K (AK) contents were the highest in the mix-cropping treatments among the three cropping systems. We suggest that rice/water mimosa mix-cropping is an environmentally friendly agroecological system with a higher output and can be extended for green rice production and largely applied in the paddy field. © 2021 Society of Chemical Industry.