Changes in photosynthesis and chlorophyll fluorescence in two soybean (Glycine max) varieties under NaCl stress

Bin Luo,Peng Song,Han Zhang,Xiaodong Wang,Wensen Wang,Cheng Wang,Yanan Zhou

doi:10.25165/j.ijabe.20211403.5941

Abstract

Traditional detection methods of crop information are often destructive and low efficiency. In this study, a new evaluation method was developed based on photosynthesis and chlorophyll fluorescence. Via analysis of the changes under NaCl stress during the seedling stage of two varieties, the salt resistance mechanism of soybeans was explored and a non-destructive stress-recognition method was developed. In this experiment, two soybean varieties were treated with one of four levels of NaCl stress: CK (0 mmol/L), LS (50 mmol/L), MS (100 mmol/L), and HS (150 mmol/L), for 15 d. The normal functions of the photosynthetic system of soybeans were enhanced under LS NaCl stress, but were inhibited under HS NaCl stress. Biomass, net leaf photosynthetic rate (Pn), stomatal conductance (gs), intercellular carbon dioxide concentration (Ci), transpiration rate (Tr), chlorophyll fluorescence parameters Y(II) and PSII decreased. However, in contrast to the findings of other studies on the influence of severe drought stress on soybean for long periods in which non-photochemical quenching coefficient (qN) decreased, this parameter increased under salt stress in soybean. The results demonstrate that the method developed is a promising tool for rapid and non-destructive detection of soybean photosynthetic responses under salt stress in the field. Keywords: biomass, chlorophyll fluorescence parameters, NaCl stress, photosynthetic parameters, soybean DOI: 10.25165/j.ijabe.20211403.5941 Citation: Luo B, Wang C, Wang X D, Zhang H, Zhou Y N, Wang W S, et al. Changes in photosynthesis and chlorophyll fluorescence in two soybean (Glycine max) varieties under NaCl stress. Int J Agric & Biol Eng, 2021; 14(3): 76–82.

Highlights

Soybean (Glycine max) is a major source of high-quality protein and oil for human consumption[1]
3.1 Effects of salt stress of soybean on biomass As shown in Table 1, the seedling-stage biomass of the two soybean cultivars under 50 mmol/L (LS) stress exceeded those under 0 mmol/L (CK)
There was a significant increase in the root:shoot ratio of Qihuang 35, and after salinity reached 177.0% of CK under 100 mmol/L (MS) NaCl stress, it declined to 139.2% under HS stress

Summary

Introduction

Soybean (Glycine max) is a major source of high-quality protein and oil for human consumption[1]. Soybean production may be limited by environmental stress factors, such as soil salinity[2]. It is well known that salt stress can cause marked inhibition of photosynthetic efficiency and restrict crop survival rate, yield, while degrading the quality of agricultural products[3,4,5,6]. Improvement and utilization of soil salinity can effectively relieve problems such as low grain productivity, crop species restrictions, and ecosystem damage caused by world population growth and the concomitant reduction of arable land[11]. Soil salinization has occurred in major soybean-producing areas of China at different degrees of severity. An understanding of how to select salt-tolerant soybean varieties and how to predict salt stress can facilitate increases in soybean yield effectively in saline and alkaline areas

Methods

Results

Discussion

Conclusion