Acetic acid mitigated salt stress by alleviating ionic and oxidative damages and regulating hormone metabolism in perennial ryegrass (Lolium perenne L.)

Organic chemical priming is an effective strategy in mitigating salt stress to plants.The objective of this study was to determine effects and associated mechanisms of acetic acid regulating plant tolerance to salt stress.Perennial ryegrass plants were pre-treated with 20 mM acetic acid and subsequently subjected to salt stress for 28 days.Salt stress caused increased endogenous acetic acid content with up-regulated expression of its key biosynthetic gene LpPDC1.Application of acetic acid effectively alleviated salt caused damage in perennial ryegrass.Acetic acid treatment increased K^(+) content and suppressed Na^(+) accumulation to maintain a higher K^(+)/Na^(+) ratio in leaves exposed to salt stress.Plants O_(2)^(−) treated with acetic acid also had significantly lower levels of and H_(2)O_(2),but higher SOD and CAT activities than those of the control after 21 days of salt stress.Acetic acid treatment also altered the plants endogenous phytohormone content with higher content of jasmonate(including JA,JA-ILe,and cis-OPDA),auxin(IAA),and cytokinins(CK,such as tZ,cZR,and iP),but lower content of abscisic acid(ABA)under salt stress conditions.Furthermore,expression of genes involved in JA,IAA,and CK biosynthesis and signaling pathways were up-regulated,while those involved in ABA were down-regulated by acetic acid treatment under salt stress.The results demonstrate that acetic acid could mitigate salt stress in perennial ryegrass by regulating K^(+) and Na^(+) balance,promoting ROS scavenging,and activating stress-protection hormone synthesis and signaling.

Life cycle assessment on the environmental impacts of different pig manure management techniques

The management of livestock waste is an effective way to achieve emission reduction and carbon fixation in agriculture and rural areas.At present,aerobic composting and anaerobic fermentation are widely used in livestock waste treatment technology.In this study,pig manure management was taken as an example,a comprehensive environmental load index was constructed to quantitatively evaluate the environmental impacts of global warming,environmental acidification,eutrophication,and photochemical ozone synthesis during aerobic composting and anaerobic fermentation based on the life cycle assessment.The results showed that the potential values of aerobic composting and anaerobic fermentation were similar,and the order was global warming,environmental acidification,eutrophication,and photochemical ozone synthesis.Anaerobic fermentation contributed more to global warming,while aerobic composting contributed more to environmental acidification,eutrophication,and photochemical ozone synthesis.In addition,the environmental load index of aerobic composting was significantly higher than that of anaerobic fermentation.There were certainly regional differences in the environmental load index,and the environmental impact effect of anaerobic fermentation was low and more environmentally friendly.These findings provided a technical basis for livestock manure management in different regions of China,which was conducive to promoting animal husbandry emission reduction and carbon sequestration.