Mitigation Effects Of Exogenous Abscisic Acid And Humic Acid On Low Temperature Stress Of Dwarf Bamboos

In this experiment,five dwarf bamboo species,namely SA Sasa argenteostriata(Regel)E.G.Camus,Sasa fortune(Van Houtte)Fiori,Sasaella glabra(Nakai)f.albo-striata Muroi,Shibataea lanceifolia C.H.Hu and Indocalamus decorus Q.H.Dai,were selected and treated with the nature low temperature stress.For the purpose of investigating the mitigation effect of exogenous ABA on low temperature stress of various bamboos,physiological response,plant growth,and ornamental characteristics of different species were determined at different concentrations(0,12.5,25,50,100 mg/L)of exogenous ABA treatments.In addition,Sasa argenteostriata(Regel)E.G.Camus,which was the the lowest tolerance specie was further used to explore the stress mitigation effect of the plant regulators at different concentrations of ABA(12.5,25,50 mg/L)and HA(40,60,80 mg/L).Results showed that:(1)In the stress physiological response of five dwarf bamboo species,exogenous ABA showed a low promotion and high inhibition effect on the stress resistance of them under low temperature stress.12.5～50 mg/L ABA treatments reduced the leaf REC of each bamboo species,and increased their RWC,Pro,SP levels and SOD activities,which enhanced the physiological tolerance of each species.However,the high-concentration ABA treatments of 100 mg/L increased the leaf REC of the the studied bamboos(except Sasa fortune(Van Houtte)Fiori),meanwhile,significantly reduced the Pro contents of Sasa fortune(Van Houtte)Fiori and the SOD activities of Sasaella glabra(Nakai)f.albo-striata Muroi,which aggravated the appreciation of the bamboos low temperature stress damage instead.(2)In terms of the growth and development of five studied bamboos,12.5～50 mg/L(low and medium concentrations)ABA treatments displayed a positive effect on alleviating the morphological damage of the bamboos,which improved the cold resistance indexes of their leaves.Meanwhile,ABA treatments had increased the scores of landscape quality evaluation of the Sasa fortune(Van Houtte)Fiori,Sasaella glabra(Nakai)f.albo-striata Muroi and Shibataea lanceifolia C.H.Hu in the deep winter period,as well as the Sasa argenteostriata(Regel)E.G.Camus and Indocalamus decorus Q.H.Dai in the overwinter period.In contrast,100 mg/L(high concentration)ABA treatments all significantly reduced the leaf cold tolerance indexes of bamboo species expect for Sasa argenteostriata(Regel)E.G.Camus species during the deep winter period,which was not conducive to maintaining the winter ornamental value of the bamboos.(3)The mitigation effect of exogenous ABA under low temperature stress was different for the optimum concentration of different bamboo species.Based on the stress resistance physiology response and growth of various bamboo species,12.5 mg/L ABA treatments established the best facilitation on improving the cold tolerance of Sasa argenteostriata(Regel)E.G.Camus and Sasaella glabra(Nakai)f.albo-striata Muroi;25 mg/L ABA treatment was best used to facilitate the cold resistance of Sasa fortune(Van Houtte)Fiori and Indocalamus decorus Q.H.Dai;50 mg/L ABA treatment had the best effect on improving the Shibataea lanceifolia C.H.Hu.As far as the landscape quality,12.5～25 mg/L ABA treatments had the best positive effect on alleviating the morphological damage caused by low temperature stress of Sasa argenteostriata(Regel)E.G.Camus,Sasaella glabra(Nakai)f.albo-striata Muroi,Sasa fortune(Van Houtte)Fiori and Indocalamus decorus Q.H.Dai,and 25～50 mg/L ABA treatments showed the most effective to help relieve this damage of Shibataea lanceifolia C.H.Hu on the stress.(4)HA compound treatments could further improve the alleviation of low temperature stress of exogenous ABA on the bamboos,which played a stress relieving effect in synergy with ABA.In the comprehensive evaluation of cold tolerance,the physiological indicators(REC,MDA,RWC,Pro,SP,SS levels,SOD activity),and the tolerance index and the number of shoots of the bamboo were selected for the principal component analysis of the combination.According to the comprehensive evaluation of membership function method,ABA-12.5/HA-80 was considered as the best compounding treatment for improving the comprehensive tolerance of Sasa argenteostriata(Regel)E.G.Camus under low temperature stress.In terms of landscape quality,the treatment of 12.5 mg/L ABA and 60～80 mg/L HA was most effective in alleviating the morphological damage of Sasa argenteostriata(Regel)E.G.Camus under low temperature stress during the winter.