Physiological Responses And Changes In Yield And Quality Of Potato "Kexin 1" And "Jizhangshu 8" Under Drought Stress

Drought is an important factor affecting plant growth.In order to clarify the effect of drought stress on potato,"Kexin 1"and"Jizhangshu 8"potato varieties were used as research materials.By artificially controlling the relative soil water content,potato was subjected to three levels of continuous drought stress treatment:control group（soil relative water content was70%～75%）,moderate drought stress group（40%～45%）and severe drought stress group（20%～25%）.The morphological indexes,physiological indexes,tuber yield and quality of two potato varieties under different degrees of drought stress were analyzed.Reveal the relationship between the indicators and yield.The main conclusions are as follows:（1）Drought stress inhibited the plant height,stem diameter,stolon number,branch number,leaf water content and stem water content of potato plants,which were proportional to their soil relative water content.Comparing the morphological characteristics of the two potato varieties under drought stress,the inhibitory effect of drought stress on"Kexin 1"was more obvious.（2）With the decrease of soil relative water content,the proline content,soluble protein content,superoxide dismutase activity,peroxidase activity and malondialdehyde content in potato leaves gradually increased and the highest in severe drought stress group,followed by moderate drought stress group and control group.Compared with the two potato varieties,drought stress had a greater impact on the early growth stage of"Jizhangshu 8"and a greater impact on the late growth stage of"Kexin 1".（3）Drought stress inhibited the photosynthesis of potato.With the decrease of soil relative water content,the chlorophyll content,net photosynthetic rate,intercellular CO₂concentration,stomatal conductance and transpiration rate of potato leaves gradually decreased and the control group had the highest value,followed by moderate drought stress group and severe drought stress group.Comparing the two varieties,the photosynthesis of"Jizhangshu 8"was stronger than that of"Kexin 1".（4）Potato tuber yield and tuber protein content,starch content,vitamin C content,reducing sugar content were inversely proportional to the degree of drought stress,the higher the soil relative water content,the higher the value of the above indicators.Comparing the yield of the two varieties,the yield of"Kexin 1"was higher in the control group and the moderate drought stress group,while the yield of"Jizhangshu 8"was higher under severe drought stress.Compared with the tuber quality of the two varieties,the protein content and starch content of"Jizhangshu 8"were higher,while the vitamin C content and reducing sugar content of"Kexin 1"were higher.Compared with the drought resistance coefficient of the two varieties,the drought resistance coefficient of"Jizhangshu 8"under moderate and severe drought stress was0.93 and 0.78,respectively,which was higher than that of"Kexin 1".（5）The plant height,stem diameter,branch number,stolon number,leaf water content,stem water content,leaf chlorophyll content,net photosynthetic rate,intercellular CO₂concentration,stomatal conductance,transpiration rate,tuber protein content,reducing sugar content,vitamin C content and starch content of the two potato varieties were positively correlated with tuber yield,while the proline content,soluble protein content,superoxide dismutase activity,peroxidase activity and malondialdehyde content of leaves were negatively correlated with tuber yield.Among them,plant height,stolon number,net photosynthetic rate,stomatal conductance,transpiration rate and other indicators were closely related to yield.The highest correlation degrees were 0.839,0.849,0.929,0.945 and 0.915,respectively.In summary,drought stress had a strong inhibitory effect on"Kexin 1"potato.In the control group,the yield of"Kexin 1"was higher than that of"Jizhangshu 8".In the moderate drought stress group,the drought resistance coefficient of"Jizhangshu 8"was higher but the yield was lower than that of"Kexin 1",while the drought resistance coefficient and yield were higher than those of"Kexin 1"potato under severe drought stress.