Nitrogen application improved photosynthetic productivity, chlorophyll fluorescence, yield and yield components of two oat genotypes under saline conditions
Citation
Song, X., Zhou, G., Ma, B.L., Wu, W., Ahmad, I., Zhu, G., Yan, W., Jiao, X. (2019). Nitrogen application improved photosynthetic productivity, chlorophyll fluorescence, yield and yield components of two oat genotypes under saline conditions. Agronomy, [online] 9(3), http://dx.doi.org/10.3390/agronomy9030115
Plain language summary
Oat (Avena sativa L.), as a crop both for grain and forage uses, has obtained renewed attention worldwide due to its rich-nutrient with high protein content, minerals, and dietary fibers. With population growth and increasing demand for food, large fertile farming lands previously cultivated to oat have been replaced by other high-yielding crops like rice and maize. Oat production has moved to marginal lands that are prone to salt accumulation, since it is more salt-tolerant than most food crops. However, the increasing saline stress, due to high evapotranspiration and limited rainfall as well as poor soil management, has adversely affected its growth, nutritive value, and yield capacity. Proper application of fertilizer is a convenient and effective practice to improve yield and nutritive value for oat plants. Nitrogen has been recognized as an essential management practice to supply nutrition for oat growth and yield improvement. However, little information is available regarding the interactive effects of salinity and N fertilization on the physiological and yield responses. Information regarding the interactive effects between salt stress and N fertilization on crop performance will be useful for improving current exploitation practices to establish oat plants in salt-affected soils. This study aims to
(1) determine the physiological (photosynthetic rate and chlorophyll fluorescence parameters) and yield response to interactive effects between N application rate and saline stress for two oat genotypes;
and (2) verify whether increasing N application could alleviate the negative effects of saline stress in
terms of grain yield and physiological parameters.
A controlled pot culture experiment was done for two times at the Ottawa Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), Ontario, Canada. The nitrogen, salinity levels, and other practices were totally the same in the two runs. Gas exchange, chlorophyll fluorescence, and electrical conductivity
(EC) were determined for both runs. Grain yield and yield components were only recorded in the second run.
In this study, we found that the photosynthetic rate, nitrogen use efficiency, plant height, and grain yield were significantly affected by the interaction of salinity stress and N fertilization. Our results illustrated that N fertilization can alleviate the negative effects induced by salinity stress and improve plant growth and yield by maintaining the integrity of the physiological processes of oat plants. Our study provided new evidence that increased N application can be regarded as a key agronomic practice for improving oat production in soil salinity, which is essential for agronomists and producers to make proper decisions in fertilization management in salt-affected soils.
Abstract
Understanding the interaction between salinity and nitrogen (N) nutrition is of great economic importance to improve plant growth and grain yield for oat plants. The objective of this study was to investigate whether N application could alleviate the negative effect of salinity (NaCl) stress on oat physiological parameters and yield performance. Two oat genotypes with contrasting salt tolerance response (6-SA120097, a salt-tolerant genotype SA and 153-ND121147, salt-sensitive ND) were grown under four N rates (0, 100, 200, and 400 mg N pot -1 ) in non-saline and saline (100 mM NaCl) conditions. The results showed that salinity, N fertilization and their interaction significantly affected the photosynthetic rate, transpiration rate, agronomic nitrogen use efficiency (aNUE), physiological nitrogen efficiency (pNUE) and apparent nitrogen recovery (ANR), seed number, and grain yield. Saline stress reduced gas exchange rate, nitrogen use efficiency (NUE), grain yield, and yield components. N fertilization increased photosynthetic productivity and chlorophyll fluorescence, resulting in improved grain yields and yield components for both genotypes. On average, the photosynthetic rate was increased by 38.7%, 74.1%, and 98.8% for SA and by 49.8%, 77.6%, and 110% for ND, respectively, under the N rates of 100, 200, and 400 mg N pot -1 , as compared with non-fertilized treatment. In addition, grain yield was increased by 80.6% for genotype SA and 88.7% for genotype ND under higher N application rate (200 mg N pot -1 ) in comparison with the non-nitrogen treatment. Our experimental results showed that an increase of N supply can alleviate the negative effects induced by salinity stress and improved plant growth and yield by maintaining the integrity of the photosynthesis and chlorophyll fluorescence processes of oat plants, which provides a valuable agronomic strategy for improving oat production in salt-affected soils.