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Effects Of Pre-winter Irrigation On Soil Temperature,Moisture And Overwintering Physiology Of Alfalfa

Posted on:2021-04-18Degree:MasterType:Thesis
Country:ChinaCandidate:Q GaoFull Text:PDF
GTID:2393330602993226Subject:Grass science
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Alfalfa is an important forage species for animal husbandry.In recent years,the planting area of alfalfa has been expanding continuously in the north.Low temperature and strong wind often occur in these areas,which makes it difficult for alfalfa to overwinter.This study attempted to examine the influence of different winter irrigation systems on physiological characteristics of alfalfa in relation to overwintering.Two experiments were carried out: a field experiment and a laboratory experiment.The laboratory experiment was conducted in a low-temperature illumination incubator to simulate the field environment during the overwintering period,and to explore the effect of winter irrigation on the physiological indicators of alfalfa crown.The field experiment was conducted at the experimental station of the Chinese Academy of Agricultural Sciences(CAAS)located in Langfang,Hebei Province.During the wintering period of 2018/2019,different treatments of pre-winter irrigation water were applicated in field plots prior to freezing.The soil volume water content and soil temperature during the wintering period were recorded,and the winter survival rate was investigated in March 2019.The main findings are as follows:1.The laboratory experiment involved four treatments,namely(i)watering only,(ii)mulching only(iii)mulching after watering,and(iv)control(either watering nor mulching).A low-temperature light incubator was used to simulate the overwintering environment and various physiological indexes and cold-tolerance of alfalfa under different treatments were measured.the results showed that malondialdehyde content in the root and crown of alfalfa increased with the decrease of temperature,and it was significantly lower in low dormancy variety and the plants in the watering treatment.Low temperature also led to an accumulation of soluble sugar and soluble protein in the root and crown,winter irrigation can significantly increase the accumulation of these substances.2.The field plot experiment in the r winter period consisted of three pre-winter irrigation treatments,namely(i)60 mm,(ii)40 mm and(iii)20 mm and the soil temperature and moisture were recorded over the experiment period.The results showed that the soil temperature and volume-water content with the largest winter irrigation treatment were higher than others during the overwintering period,and the moisture content in deeper soil was also higher after thawing in spring.This indicated that a higher pre-winter irrigation could increase the soil temperature in the field,and particularly in could result in higher soil moisture during the recovering growth period in the spring.3.The effects of different pre-winter irrigation treatments on winter survival and cold-tolerance of alfalfa were examined in the field plot experiment.The results showed that the highest overwintering rate was recorded in the treatment with the largest amount of irrigation,which also had a significantly lower MDA content and higher soluble sugar and free proline contents in the root and crown than the other treatments,This also indicated that a higher pre-winter irrigation could increase substances related to cold-resistant in alfalfa root and crown,which in turn could protect alfalfa from cold damage and thus to improve the winter survival.
Keywords/Search Tags:Alfalfa, Winter irrigation, Cold resistance, Winter survival
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