Effects of strigolatone on the growth and development of chilli pepper under salinity,heat,and their combined stresses

WEI Jianye; XU Chunmiao; ZHANG Guobin; NIU Tianhang; MAO Zhenyu; FAN Taohui

doi:10.16861/j.cnki.zggc.2025.0118

Abstract：This study employed a split-plot design to investigate the mitigating effects of exogenous strigolactone ana-logue GR24 on pepper(Capsicum annuum L.)seedlings subjected to salt stress(S,150 mmol·L-1 NaCl),heat stress(H,35 ℃ day/28 ℃ night),and combined salt-heat stress(S+H).The main plots comprised four stress treatments:control(CK,normal conditions),salt stress(S),heat stress(H),and combined stress(S+H).The subplots consisted of five GR24 concentration levels(G0 to G4:0,0.05 × 10-6,0.1 × 10-6,0.15 × 10-6,0.2 × 10-6 mol·L-1).A comprehensive assess-ment of stress resistance capacity was conducted by measuring thirty-four parameters encompassing seed germination,morphological and physiological traits,photosynthetic characteristics,nitrogen metabolism,and yield,with data integrated using the fuzzy membership function method.Results identified 0.1 × 10-6 mol·L-1 GR24(G2)as the optimal concentra-tion across all stress conditions,significantly enhancing pepper stress tolerance and physiological metabolic functions.During seed germination,exogenous GR24(0.1 × 10-6mol·L-1)significantly alleviated the inhibitory effects of all stress-es:increasing the salt-stressed(S)germination rate by 10.59％,restoring the heat-stressed(H)seedling survival rate to 78.08％of CK,and increasing the combined-stress(S+H)germination rate by 30.67％.However,under S+H,the seed-ling survival rate remained 6.64％lower than under S alone.During the vegetative/growth stage,S-G2 treatment signifi-cantly restored plant height and single fruit mass to near CK levels compared to S-G0.Relative to CK-G0,S-G2 exhibited a net photosynthetic rate(Pn)of 16.78 μmol·m-2·s-1,a recovered SPAD value of 39.67,nitrogen metabolism enzyme(NR,GS)activities reaching 82.01％and 80.36％of CK,fruit capsaicin content restored to 94.40％of CK,and total yield recovered to 89.61％of CK.Under heat stress,H-G2 treatment demonstrated significantly superior root activity and super-oxide dismutase(SOD)activity compared to other H treatments.Proline content in H-G2 decreased by 35.40％relative to H-G0,approaching CK levels,while yield per plant recovered to 84.42％of CK.For combined stress(S+H-G2),root surface area and Pn were significantly higher than S+H-G0.Comprehensive evaluation confirmed that GR24 provided superior mitigation under single stresses compared to combined stress,with respective comprehensive values of 0.76(S),0.68(H),and 0.61(S+H).In conclusion,exogenous GR24 at 0.1 × 10-6 mol·L-1 effectively mitigates the inhibitory effects of single salt and heat stress on pepper,restoring key physiological and yield indicators to 76％-95％of CK levels,thereby offering an efficient physiological regulation strategy for cultivation under adverse environmental conditions.