Scheduling of nitrogen fertilizer topdressing during panicle differentiation to improve grain yield of rice with a long growth duration

Yang Liu,Yuzhu Zhang,Xinguang Zhu,Xiaoe He,Haiqing Zhang,Chao Li,Tiangen Chang,Shuoqi Chang

doi:10.1038/s41598-020-71983-y

Abstract

Topdressing at panicle differentiation (PF) according to soil fertility and regularity of rice nutrient absorption is an important agronomic practice used in cultivation of rice cultivars with a long growth duration. We studied the impacts of timing of nitrogen fertilizer application during PF on photosynthesis and yield-related agronomic traits in ‘Y-Liang-You 900’ and ‘Y-Liang-You 6’, which are representative rice cultivars with a long growth duration. Data for two years showed that timing of topdressing application during PF affected panicles per unit area, percentage grain set, spikelets per panicle, and leaf photosynthetic traits during the grain-filling period. Topdressing at the initial stage of flag-leaf extension resulted in higher grain yield (typically by 10.55–19.95%) than in plants without topdressing. Grain yield was significantly correlated with flag leaf photosynthetic rate and leaf SPAD value (r = 0.5640 and r = 0.5589, respectively; p < 0.01) at an advanced grain-filling stage (30 days after heading). Surprisingly, grain yield was not correlated with carbohydrate remobilization from the stem and sheath. For rice cultivars with a long growth duration, nitrogen-fertilizer topdressing must be applied at the initial stage of flag-leaf extension to delay leaf senescence during the grain-filling stage and realize the enhanced yield potential.

Highlights

Topdressing at panicle differentiation (PF) according to soil fertility and regularity of rice nutrient absorption is an important agronomic practice used in cultivation of rice cultivars with a long growth duration
The panicle number of PFs ranged from 212.28 × 104 to 237.24 × 104 ha−1, which was higher than that of the NPF and no fertilizer treatment (NF) treatments by approximately 9% and 42%, respectively
NF resulted in the highest grain set of approximately 90%, whereas PF-5 resulted in percentage grain set of 83.59% and 88.94% for YLY900, and 83.29% and 85.87% for Y-Liang-You 6’ (YLY6) in 2016 and 2017, respectively, which were higher than those observed for NPF and the other PF treatments (Table 2)

Summary

Introduction

Topdressing at panicle differentiation (PF) according to soil fertility and regularity of rice nutrient absorption is an important agronomic practice used in cultivation of rice cultivars with a long growth duration. For rice cultivars with a long growth duration, nitrogen-fertilizer topdressing must be applied at the initial stage of flag-leaf extension to delay leaf senescence during the grain-filling stage and realize the enhanced yield potential. The HI of many elite rice cultivars has already attained an extremely high value (above 0.5), further improvement of the yield potential is reliant on an increase in b iomass[7] This realization is already reflected in current rice breeding programs, in which genotypes with a long growth duration, characterized by a longer grain-filling period, are selected for greater biomass production and correspondingly higher grain yield at harvest, as exemplified by ‘Y-Liang-You 900’8–10. Different topdressing schedules can differentially influence photosynthetic efficiency[13] and panicle differentiation, thereby resulting in differences in panicle number per plant and number of seeds per panicle[14,15,16], and the functional longevity of leaves during the grain-filling s tage[17,18,19]

Results

Discussion

Conclusion