Effects of Postponing Topdressing-N on the Yield of Different Types of japonica Rice and Its Relationship with Soil Fertility

Abstract

N fertilizer is usually supplied via multiple applications in rice production in China. Due to the high N-recovery efficiency (NRE) of panicle fertilizer, applying large amounts of fertilizer at the booting stage is considered to be an effective measure of increasing yields, although it has adverse effects on eating quality. In this study, using six inbred and four hybrid japonica varieties, we postponed topdressing-N to increase the ratio of panicle N from 20% to 40% by correspondingly reducing the N amount applied only at the tillering stage. We also analyzed the effects of postponing the topdressing-N on grain yield and dry matter accumulation in both high- and low-fertility blue clayey paddy fields in 2016 and 2017. The effects of postponing topdressing-N applications on japonica rice were related to variety, meteorological conditions, and soil fertility. With respect to the inbred varieties, regardless of whether panicle N was applied as a single or split application, increasing the ratio of panicle N had no effect on the yield components or dry matter accumulation of plants grown in either high- and low-fertility soils. Regarding the hybrid varieties grown in the high-fertility soil, although postponing the topdressing-N application had no effect on yield under good weather conditions (no low-temperature stress during grain-filling), a single application of 40% of the total N at the panicle initiation stage significantly decreased both the dry matter accumulation after heading and the seed-setting rate of varieties that presented long growth periods under low-temperature conditions. With respect to hybrid varieties grown in low-fertility soil, postponing the application of topdressing-N had an adverse effect on the number of effective panicles. Our results suggested that the proportion of panicle N applied to japonica rice should not exceed 30% in clayey paddy fields and that fertilizer management with respect to rice production should be adjusted according to soil type, soil fertility, and variety.

Increasing the yield of drip-irrigated rice by improving photosynthetic performance and enhancing nitrogen metabolism through optimizing water and nitrogen management

“…These findings show that the study of drip irrigation rice is of great value for promoting largescale upland rice production and improving water and nitrogen utilization efficiency in arid areas. However, the yield and NUE of the two cultivars were not significantly different from those under alternate dry−wet irrigation, which may be related to the cultivars (Jehangir et al, 2022), ecological conditions (Naeem et al, 2022), soil types (Ye et al, 2019), and cultivation methods (Sandhu and Mahal, 2014).…”

Effects of nitrogen application on seed yield, dry matter and nitrogen accumulation of Siberian wildrye (Elymus sibiricus L.)

“…The seed yield of grass species is greatly dependent on inflorescence morphological traits, starting with spikelets per inflorescence and seeds per spikelet, to kernel size, and then to awns (Dreccer et al, 2019;Severova et al, 2022). Besides, Seed yield in grasses is also known to be associated with a number of seed yield components, such as by fertile tillers m −2 , spikelets per fertile tiller, seed number per plant and 1000-grain weight seed yield (Bhutto et al, 2016;Vafa et al, 2021;Ye et al, 2019). These traits are important and complex to realize high seed yields.…”

Reasonable Nitrogen Regime in the Main Crop Increased Grain Yields in Both Main and Ratoon Rice

“…Zhu et al (2017) and Liang et al (2021) revealed that rice yield first increased and then decreased with increasing N application rate [37,38], and we reached a similar conclusion (Figure 1A-C). Ye et al (2019) indicated that N application at a later stage of rice reduced the panicle number and was not conducive to increasing grain yields [39]. However, Li et al (2018) reported that increasing the proportion of panicle N fertilizer improved N use efficiency and increased grain yield [40].…”