Effects of nitrogen fertilizer rates on grain yield and nitrogen use efficiency of japonica-indica hybrid rice cultivar Yongyou 1540 and its physiological bases
Year: 2023
Type: article
Abstract: The objective of this study is to understand how nitrogen (N) application rates affected on grain yield and N use efficiency (NUE) of japonica-indica hybrid rice cultivar Yongyou-1540 and its physiological bases. In the present study, a japonica-indica hybrid rice cultivar Yongyou 1540, which was widely planted in Zhejiang province was field grown in 2020 and 2021, and four N application rates [0 kg hm-2 (N0), 80 kg hm-2 (N1), 160 kg hm-2 (N2), and 240 kg hm-2 (N3)] were applied during rice growing season. The results indicated that, (1) N application rate had significant effects on grain yield and NUE of rice. Grain yield was significantly increased with the increase of N application rate from 0 kg hm-2 to 160 kg hm-2, and the increase in grain yield was mainly attributed to the increase in total spikelets per unit area. However, there were no significantly difference in grain yield between N2 and N3 treatments, which was mainly due to the reduce in grain filling percentage in N3 treatment. When compared with N2 treatment, N3 treatment significantly reduced N harvest index and NUE, including agronomic N use efficiency (AEN), N recovery efficiency (REN), N partial factor productivity (PFPN), and internal N use efficiency (IEN). (2) N application rate had significant effects on shoot growth and development. Shoot dry weight was significantly increased at jointing, heading, and maturity stages and harvest index was significantly decreased with the increase of N application rate from 0 kg hm-2 to 240 kg hm-2. The net photosynthetic rate of flag leaf, the concentration of zeatin plus zeatin riboside (Z+ZR) in flag leaves, and the activities of key enzymes involved in sucrose-to-starch conversion in grains were significantly increased with the increase of N application rate from 0 kg hm-2 to 160 kg hm-2, however, N3 treatment could not increase or even reduce the above indicators compared with N2 treatment. (3) N application rate had significant effects on rice root morphological and physiological traits. Root dry weight, root dry weight in both 0-10 cm and 10-20 cm soil layers, total root length, root length density, specific root length at jointing, heading, and maturity stages, and root oxidation activity (ROA) and concentration of Z+ZR in both roots and root-bleeding sap at mid- and late grain filling stages were significantly increased with the increase of N application rate from 0 kg hm-2 to 160 kg hm-2. However, when compared with N2 treatment, N3 treatment significantly increased root dry weight, and root dry weight in 0-10 cm soil layer, total root length and root length density. (4) The results of the correlation analysis showed that ROA, and concentration of Z+ZR in roots or in root-bleeding sap, were significantly positively correlated with net photosynthetic rate of flag leaves, the concentration of Z+ZR in flag leaves, and activities of key enzymes involved in sucrose-to-starch conversion in grains. Generally, the appropriate N application rate could improve rice root morphological and physiological traits and promote shoot growth and development, and then improved plant physiological performances during the mid- and late grain filling stages, and finally achieved the due goal of increase both grain yield and NUE.
Source: ACTA AGRONOMICA SINICA
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: gold
Estimated APC paid: $941
OpenAlex ID: W7119055912