An investigation on possible effect of leaching fractions physiological responses of hot pepper plants to irrigation water salinity

Rangjian Qiu,Zhenchang Wang,Zaiqiang Yang,Ningbo Cui,Chunwei Liu,Fusheng Li

doi:10.1186/s12870-019-1910-z

Abstract

BackgroundThe modification effect of leaching fraction (LF) on the physiological responses of plants to irrigation water salinity (ECiw) remains unknown. Here, leaf gas exchange, photosynthetic light–response and CO2–response curves, and total carbon (C) and nitrogen (N) accumulation in hot pepper leaves were investigated under three ECiw levels (0.9, 4.7 and 7.0 dS m− 1) and two LFs treatments (0.17 and 0.29).ResultsLeaf stomatal conductance was more sensitive to ECiw than the net photosynthesis rate, leading to higher intrinsic water use efficiency (WUE) in higher ECiw, whereas the LF did not affect the intrinsic WUE. Carbon isotope discrimination was inhibited by ECiw, but was not affected by LF. ECiw reduced the carboxylation efficiency, photosynthetic capacity, photorespiration rate, apparent quantum yield of CO2 and irradiance–saturated rate of gross photosynthesis; however, LF did not influence any of these responses. Total C and N accumulation in plants leaves was markedly increased with either decreasing ECiw or increasing LF.ConclusionsThe present study shows that higher ECiw depressed leaf gas exchange, photosynthesis capacity and total C and N accumulation in leaves, but enhanced intrinsic WUE. Somewhat surprisingly, higher LF did not affect the intrinsic WUE but enhanced the total C and N accumulation in leaves.

Highlights

The modification effect of leaching fraction (LF) on the physiological responses of plants to irrigation water salinity (ECiw) remains unknown
The objectives of this study are (1) to analysis the response of photosynthetic capacity, intrinsic water use efficiency (WUE) and total C and N accumulation of hot pepper leaves exposed to different Irrigation water salinity (ECiw) treatments, and (2) to assess the modification effect of LF on leaf gas exchange, intrinsic WUE, and total C and N accumulation to ECiw
Compared to the ECiw of 0.9 dS m− 1, the treatment with ECiw of 7.0 dS m− 1 decreased photosynthesis rate (Pn) and gs by 37.7 and 60.5%, respectively, showing that Pn declined slower than gs, which led to a higher intrinsic WUE (i.e. Pn / gs) with higher ECiw (Table 1)

Summary

Introduction

The modification effect of leaching fraction (LF) on the physiological responses of plants to irrigation water salinity (ECiw) remains unknown. The shortage of fresh water is a principal factor restricting the development of irrigated agriculture. The use of saline water is a possible alternative to meet the increased water demands for irrigation [1]. In 2016, global pepper production (fresh and dry) from some 4 million ha was estimated at some 39 million tonnes, increasing by some 30% in the last decade [2]. Increasing demand for pepper is perhaps not surprising for high nutritional value of pepper. The total water requirement for pepper cultivation is by no means small ranging from 500 to 900 mm and up to 1250 mm in some areas [3].

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