Resistance Of Carya Illinoensis Under Water-flooding

The frequent summer rainstorm in the Yangtze River Basin is a frequent area of flood disaster in China.Therefore,cultivating planting materials with strong water-logging tolerance is of great significance to enrich the afforestation tree species in the middle and lower reaches of the Yangtze River in China.A pot experiment was carried out to control water in greenhouse,and 6kinds of treatments were carried out in control group,water a group,water immersion group,shallow flooded group,semi-flooded group and deep flooded group.Leaves are the main organ of light contract,root systems are the main source of nutrients such as water and inorganic salt absorbed by plants actively from soil,and they are also the most obvious organs after flooding stress.Therefore,the change of leaf and root system of thin shell pecan under water-flooding treatment is helpful to reveal the mechanism of water-logging tolerance and provide theoretical basis for large area planting and popularization of Carya illinoensis in Yangtze River Basin.(1)Analysis of morphological characteristicIn this study,1a Carya illinoensis were compared with water stains,flooding,shallow flooding,semi-flooding and deep flooding.The changes of plant growth,morphology and photosynthesis indexes were measured by flooded 120 d,the physiological and biochemical indexes were measured by flooded 24 d?48 d?72 d?96 d?120 d respectively,and the flood resistance ability of Carya illinoensis was evaluated,thus providing a theoretical basis for the large-area planting and promotion of Carya illinoensis in the Yangtze River basin.(2)Analysis of growth indicatorsFlooding stress significantly inhibited the growth of the underground part of Carya illinoensis.Under flooding,below 0.5 mm fine root lengths below 73.51-78.91 percent,the proportion of surface area is 10.85-12.05,all were lower than the control group;0.5-2 mm fine root length is 19.46-24.52 percent,the proportion of surface area is 26.63%-37.81%,all were higher than the control group.Compared with before flooding,the plant height decreased by0.15%-0.72% under water immersion,shallow flooding,semi-flooding and deep flooding.The ground diameter increased by 5.12%-45.48%,the control group and the water stains group maintained normal growth.As the flooding time increases,the growth status of thin shell pecans decreased gradually.But the survival rate was more than 83.3%.(3)Analysis of photosynthetic indicatorsUnder different treatments,the diurnal variation trend of photosynthesis of Carya illinoensis was basically single peak curve,and there was no "light lunch break" phenomenon: the net photosynthetic rate of semi-flooded group and deep-flooded group was smaller than that of control group in most periods,while the net photosynthetic rate of water-stained group was larger than that of control group,which indicated that proper flooding could improve plant photosynthesis severe flooding could inhibit.Under different treatments,the change trend of plant light response curve increased first and then stabilized: the photosynthetic ability of water stains group was stronger,which was significantly higher than that of other treatments,and the light compensation points of shallow,semi-flooded and deep-flooded groups decreased significantly,indicating that severe flooding enhanced the ability of plants to use weak light.(4)Analysis of physiological and ecological indicatorsThe antioxidant activity in the 120 d,shallow,semi-flooded and deep-flooded groups were significantly higher than the control group,increasing by over 60% and increasing with water depth.The content of soluble sugar and soluble proteins in the shallow,semi-flooded and deep-flooded groups was significantly higher than the control group,increasing above 74%;while chlorophyll and root vitality were lower than the control group,and the deeper the flooding depth,the greater the reduction.The shape,growth,photosynthesis,physiology and biochemistry of Carya illinoensis were not different from those of the control group.The plants adapted well to the condition of water stains.Under other flooding treatment,the morphological changes of Carya illinoensis appeared,the growth and photosynthesis were obviously inhibited,the physiological and biochemical indexes were different from those of the control group,but the survival rate was higher.It is speculated that plants maintain their survival under flooding by inhibiting their own growth and development.