Late nitrogen application enhances spikelet number in indica hybrid rice (Oryza sativa L.)

Abstract

To increase rice yield potential, field experiments were conducted in farmers' paddies in 2011 and 2012 to evaluate the effects of different nitrogen applications on the yield and panicle components of three typical indica hybrid rice varieties in Sichuan Province. The number of grains per panicle resulting from late nitrogen application (LA) was 12 % greater than that obtained from traditional nitrogen application (TA); this increase was the main source of improvements in yield. The number of surviving and differentiated spikelets (NSS and NDiS) resulting from LA was significantly higher than that measured under TA, especially for the Fyou498 cultivar, where the NSS and NDiS increased by 15 % and 14 %, respectively. Compared with TA, the number of degenerated secondary branches and the percentage of degenerated secondary branches (NDeSB and PDeSB) were significantly reduced by 9 % and 11 %, respectively, by LA. This is the first study to demonstrate that an increase in NSS and a decrease in NDeSB lead to yield-improving effects attributable to LA. The grain yields of different varieties ranged from 9225.6 to 9408.7 kg ha −1 , the PDeSB was as high as 31 %, and the number of surviving secondary branches (NSSB) was significantly and positively correlated with NSS. These data indicate that the yield of indica hybrid rice has considerable potential for being improved, and increasing NSSB is key to increasing NSS and improving the grain yield. These improvements should be pursued so as to increase the yield of hybrid rice to ensure both food security and sustainable agricultural development.

Morphophysiological mechanism of rice yield increase in response to optimized nitrogen management

“…Therefore, supplemented nitrogen determines the expression of SP1 and GS1;1 , which in turn control the yield and regulate nitrogen utilization. There is little difference in the number of differentiated secondary branches between OFA and TFA treatments; the OFA treatment decreases significantly the number of degenerated secondary branches thus increasing the number of survived secondary branches 12 . Therefore, the number of differentiated secondary branches is a consequence of the combination of downregulated MOC1 and upregulated LAX1 at T1 and T2, while the significant upregulation of MOC1 at T3 may be the main reason for the decrease in degenerated secondary branches.…”

“…Farmers can easily identify the jointing stage, and therefore, the topdressing time of OFA can be easily selected without any instruments or assays. In addition, our previous studies have demonstrated that OFA increases nitrogen use efficiency and significantly improves rice yield by increasing the number of spikelets without increasing the nitrogen fertilizer application rate 11 , 12 .…”

Yields and Yield Gaps in Lowland Rice Systems and Options to Improve Smallholder Production

“…The lower proportion of filled grains and harvest index combined with high yield and high grain number observed under RAP+NPK indicates that there was a build-up towards a higher yield potential with fertilization that was not attained, as grain filling did not take full advantage of the enhanced vegetative biomass production. This warrants further research into options for better spread of especially applied N as there are indications that more N application at later crop stage can improve grain filling hence grain yield [52][53][54][55][56].…”

Do cover crops improve the productivity and industrial quality of upland rice?

“…Nitrogen is the second most extracted nutrient, the most removed by rice (Crusciol, Fernandes, Carmeis Filho, & Alvarez, 2016a), and limits the growth and productivity of cereals (Zhou et al, 2017). Greater N availability results in increased milling yield (Reis et al, 2018) and head yield (Firouzi, 2015;Reis et al, 2018) of rice; therefore, it improves the industrial quality and can influence the price of rice (Laenoi, Rerkasem, Lordkaew, & Promuthai, 2018).…”