An innovated crop management scheme for perennial rice cropping system and its impacts on sustainable rice production

Perennial grain has been proposed to provide an effective means of ensuring both food and ecological security. The newly released cultivar of perennial rice 23 (PR23) represents a new rice production system that is based on no-tillage. Nevertheless, how perennial rice responds to this new system remains unclear. Two field experiments were conducted over four successive seasons from 2016 to 2017 in Jinghong, Yunnan Province, Southern China. Field experiment 1 showed perennial rice is an economically viable and environmentally safe cropping system compared to annual rice, and could obtain a stable and sustainable grain yield economically for successive seasons across years. In the perennial rice cropping system, N fertilizer had some negative effects on the regrowth of perennial rice. Field experiment 2 with four N rates N0, N1, N2 and N3 with 0, 120, 180 and 240 kg N ha−1, respectively and three planting densities D1, D2 and D3 with 10, 16.7 and 22.6 plants m-2, respectively on perennial rice was conducted to assess and ameliorate these negative effects of N fertilizer on the regrowth of perennial rice. The results showed that: (1) the N2D3 treatment (180 kg N ha−1 integrated with 22.6 plants m−2) resulted in a stable and high grain yield across three successive regrowth seasons (6.93 t ha−1) and optimized yield components (panicle no. m-2, spikelet no. panicle−1, grain weight) and root activity (10.81 g h−1 m-2); (2) the regrowth of perennial rice 23 was significantly limited by N fertilizer (P<0.05), and the N0D2 treatment had the best regrowth ability (97.8 %) across the three regrowth seasons; (3) additionally, the N2D3 treatment had the best N net productivity (27 kg N kg−1), profit (79 CNY kg−1) and sustainable production capacity (0.59), and could obtain more economic profit in successive perennial rice production. Perennial rice was able to be sustainably and economically produced for successive regrowth seasons across years, and the N2D3 treatment provided optimal conditions, which enhanced the regrowth rate, N productivity, economic benefit and yield potential. The use of less chemical N fertilizer and a higher planting density could enhance the sustainability of the grain yield and reduce fertilizer loss via a novel crop management scheme for perennial rice.