Effects Of Drought Stress On Characteristics Of Growth And Quality In Lilium Davidii Var.unicolor

Lilium davidii var.unicolor is a perennial herb drought-tolerant crop,which is widely used in China as a medicinal and edible plant.In order to screen out the best growth stage and stress degree to improve the quality of Lilium davidii var.unicolor medicinal food.In this study,Lilium davidii var.unicolor was used as the test material,and four different water gradient treatments were set through pot experiment,which were control(CK),normal watering every 48 h,soil relative water content was 70%～75%,mild stress(LS),soil relative water content was 50%～55%,moderate stress(MS),soil relative water content was 40%-45%,severe stress(MS).Drought stress was applied to Lilium davidii var.unicolor in seedling stage(50 days after colonization),budding stage(65 days after colonization)and flowering stage(75 days after colonization)for 30 d,respectively,and the adaptability of Lilium davidii var.unicolor to drought stress in different growth stages was analyzed,to find out the effects of drought stress at different growth stages on the growth,physiology and biochemistry,nutrient composition accumulation and secondary metabolites content of lily,and the nutritional components and secondary metabolites content of bulbs were analyzed by fuzzy membership function.The specific results were as follows:(1)Compared with CK,drought stress reduced plant height,leaf number and stem diameter.Moderate stress at seedling stage and flowering stage were beneficial to increase the number of plant roots.Moderate stress at flowering stage was beneficial to the increase of rooting number of plant stems.Drought stress in seedling stage would reduce the bulb circumference of Lilium davidii var.unicolor,and it would gradually decrease with the increase of stress.The bulb circumference was lower than CK from rehydration to harvest stage after bud stress.After 30 d of continuous stress at flowering stage,the bulb circumference reached the maximum value of 13.1 cm under LS treatment.(2)Under drought stress,the relative chlorophyll content in seedling stage and bud stage increased first and then decreased with the increasing degree of stress,while in flowering stage,except CK,the relative chlorophyll content in all treatments gradually decreased with the extension of stress time.The contents of malondialdehyde(MDA)and proline(Pro)in different growth stages reached the highest under MS treatment at 30 d stress.Under the same stress time,the activity of peroxidase(POD)increased at first and then decreased with the increasing stress.The content of POD in seedling stage and bud stage reached the highest under the stress of 30 d,and the increase rates were 44.4%and 41.1%respectively compared with CK.At seedling stage,the activity of superoxide dismutase(SOD)in each treatment increased gradually with the extension of stress time,and reached the maximum at 30 d of stress.At flowering stage,the activity of SOD in each treatment increased first and then decreased with the extension of stress time.The content of soluble protein(SP)in different growth stages was higher in MS treatment than in other treatments.(3)Moderate drought stress could increase the nutrient composition accumulation of Lilium davidii var.unicolor bulb.The content of soluble sugar was the highest under LS treatment after 30 d of continuous stress in budding and flowering stage,and the content of SP and vitamin C(VC)was highest under MS treatment in seedling stage and budding stage,and the highest under LS treatment in flowering stage.(4)After 30 d of continuous stress,MS treatment at seedling stage and bud stage promoted the accumulation of total phenols,while drought stress at flowering stage inhibited the accumulation of total phenols.The content of total flavonoids in seedling stage was promoted by MS treatment from rehydration after 30 d to harvest stage,and the content of total flavonoids in flowering stage reached the highest value under LS treatment.The flavanol content in different growth stages was the highest under LS treatment from rehydration to harvest.The content of saponins in bud stage and flowering stage was the highest under LS treatment from rehydration to harvest stage.The polysaccharide content in bud stage reached the highest value under LS treatment from rehydration to harvest stage.According to the comprehensive evaluation of membership function,the quality of Lilium davidii var.unicolor was the best under LS treatment after 30 d of continuous stress at flowering stage to harvest stage,followed by MS treatment at seedling stage.It was found that the growth and development of Lilium davidii var.unicolor was less affected by drought at the flowering stage,which was beneficial to bulb enlargement and the best quality,which could provide reference for high-quality cultivation of Lilium davidii var.unicolor in arid areas.