Effect Of Facility Temperature And Humidity Environment On Potato Cross-Breeding Fructification

As one of the world’s four major food crops,potato is rich of nutrition and grown worldwide.The increasing demand for special potatoes forces us to cultivate more special potatoes cultivars.In the process of potato hybrid breeding,external environmental factors is one of the main reasons for the low hybrid fructification rate.Especially in Jilin Province,during the potato flowering season,drought and high temperature are the main reason of drop flowers and fruit after hybrid pollination,which result in low fructification rate.The low fructification rate has seriously affected the effectiveness of potato hybrid breeding in Jilin Province.Therefore,it is one of the urgent problems for potato breeders in Jilin Province to improve the yield of hybrid fruit rate.In this study,we set three factors(temperature,humidity and soil moisture)and two environment(facility and open field condition),the ’Xindaping’ variety was used as the male parent,and the ’Zaodabai’,’Feuerita’ and ’Kexin 27’ were used as the female parent for artificial crossbreeding.We analyzed fruit setting rate under different conditions and finally confirmed the most suitable conditions for potato hybrid.The activities of protective enzymes SOD,POD and CAT on the stigmas of three female parent flowers were measured under different temperature and soil moisture to explore the effect of temperature and soil moisture on the activities of protective enzymes of potato female flowers and reveal the relationship between the enzyme activity of stigma of female flowers and stigma receptivity.This study could provide theoretical basis and data support for potato hybrid breeding.The conclusions as following:1.The optimal temperature range for artificial pollination in the facility was was between 18℃ and 23,and the temperature should stabilize at a range of 20～30℃after pollination within 4 hours.The cross combination of ’Zaodabai’ ×’Xindaping’ had the highest fructification rate,which was 39.2%;while the combination of ’Kexin27’ ×’Xindaping’ had the highest average grain number per fructification,which was 53.0.2.The suitable humidity range for potato pollination was between 75% and 90%,and this humidity should maintain at least 4 hours after pollination.The combination of ’Zaodabai’ × ’Xindaping’ had the highest fructification rate,which was 47.1%,while the combination of ’Kexin27’ × ’Xindaping’ had the highest average grain number per fructification,which was 43.7.3.Temperature,humidity and soil moisture all affected the receptivity of potato stigma.At 25℃ in the day and 20℃ in the night,stigma receptivity lasted the longest in all three varieties.When humidity was between 80% and 90%,stigma receptivity was the highest.When the soil moisture was between 70% and 90%,stigma acceptability was the highest in all three varieties.With the decrease of soil moisture,stigma receptivity lowered.4.The stigma of the three varieties presented difference in sensitivity and resistance to temperature.’Zaodabai’ presented the most sensitivity to temperature change and the worst high temperature resistance.The second was followed by’Favorita’.’Kexin27’ presented the least sensitivity to temperature and the best high temperature resistance.5.Under the three temperature conditions,the activity of SOD,POD and CAT on the stigma of three potato female parents increased first and then decreased along with the temperature change.With the passage of time after flowering,the activity of SOD and CAT increased first and then decreased,while the activity of POD decreased first and then increased.The activity of three protective enzymes changed dramatically during high temperature treatment,which was an important reason resulting in the acceleration of aging on female parent stigma.6.When the soil moisture was between 70% and 90%,the content of protective enzymes in the stigmas of the three potato varieties were the highest,and the activity of SOD,POD and CAT on the potato stigmas also lowered along with the decrease of soil moisture,resulting in the aggravation of damage from reactive oxygen free radicals on the stigmas,which was one of the reasons affecting the potato cross-breeding fructification rate.