High‐density planting with lower nitrogen application increased early rice production in a double‐season rice system

Abstract

High‐density planting is a strategy employed to save resources in crop production, particularly in environmentally friendly double‐season rice (Orvza sativa L.) cropping, where it promotes high grain yield and reduces required nitrogen (N) input. We conducted a field experiment in 2014–2018 to detect the combined effect of increased seedling density and reduced N input on early rice grain yield and N use efficiency (NUE). The higher basic seedling with low N input treatment (T2) had an average grain yield of 7.01 t ha−1, which was 16.3% greater than that of the control (CK). There was a strong linear relationship between grain yield and panicles m−2 (R2 = .82, P < .001). Grain yield increased significantly with above‐ground biomass before the full‐heading stage (R2 = .79, P < .001), which in turn promoted an increase in panicles m−2 (R2 = .85, P < .001). Mean agronomic efficiency (AE) in the T2 treatment was 34.3 kg kg−1 N, which was 48.1% higher than that in the CK treatment. Therefore, increasing seedling density from 62.5 to 176 seedlings number m−2 while reducing inorganic N input in the early season resulted in significantly higher grain yield in hand‐transplanted rice production. Our results indicate that dense planting with N reduction could improve early rice grain yield and enhance NUE.

Optimizing Planting Density and Impact of Panicle Types on Grain Yield and Microclimatic Response Index of Hybrid Rice (Oryza sativa L.)

“…An appropriate increase in planting density can increase rice yield. This is consistent with the results of Zheng et al (2020) and Ao et al (2019), while erect panicle (R499), proved to be better for highly dense planting practices.…”

Reduced Nitrogen Rate with Increased Planting Density Facilitated Grain Yield and Nitrogen Use Efficiency in Modern Conventional Japonica Rice

“…In addition, the NUEg of the 2010s' rice was also increased (p < 0.05) under RNID (Table S5). These results indicate that RNID facilitated grain yield and NUE in modern conventional japonica rice rather than the old ones, which was consistent with the studies conducted with hybrid indica rice in south and central China [23,25,27]. For three varietal types, the increased panicles per m 2 could not fully compensate for the reduction of spikelets per panicle, which resulted in lower sink size under RNID.…”

“…Many endeavors, such as reduced N rates with an increased planting density (RNID), were proposed for the optimization of grain yield and N use efficiency (NUE) in rice production. Compared with local cultivation practices (LCPs), RNID could maintain grain yield and NUE by raising panicles per m 2 [22,23], radiation interception and canopy photosynthesis potential [24,25], as well as leaf area index, shoot biomass accumulation [26], and root growth [27]. Moreover, RNID is also considered environmental friendly for mitigating greenhouse gas emissions [28,29].…”

Performance of Five Rice (Oryza sativa L.) Varieties as Influenced by Crop Establishment under Irrigated Lowland Conditions

“…According to Ewert (2004), the variation in productivity and growth is closely linked to the amount of intercepted radiation, which is primarily determined by the leaf area index. Thereby, grain yield increased with an increase in LAI (Zheng et al, 2020).…”