Frost Hazard Risk Zoning Of ’Fuji’ And ’Gala’ Apples In Ningxia

Frost is one of the major meteorological hazards in Ningxia and has a significant impact on apple from the flowering stage to the young fruit stage,which has become a limiting factor for the development of the apple industry in Ningxia.In this paper,flowers and fruits of two major apple varieties ’Gala’ and ’Fuji’ in Ningxia were used as experimental materials at the bud,bloom,fruiting and young fruit stages.The logistic equations for 20%,50%and 80%freezing rates were used to determine the critical temperatures for light,medium and heavy freezing;the changes of 10 physiological indexes of cold resistance from flowering to young fruit under low temperature stress were studied,and the main factors influencing the differences in cold resistance of apples were screened by combining the correlation between freezing rate and cold resistance indexes;and the changes of 10 physiological indexes of cold resistance from flowering to young fruit under low temperature stress were studied by combining the simulated parallel models.With the technical support of ArcGIS,we completed the risk zoning of Ningxia apple frost hazard,analyzed the change characteristics of Ningxia frost risk,and provided rationalized suggestions for the scientific layout of Ningxia apples.The main results of the study are as follows:1.The results of the tracking survey on the freezing rate showed that the cold resistance of’Gala’was stronger than that of ’Fuji’ in all periods,and the cold resistance of the same apple variety was different in different phenological periods,as follows:bud period>flowering period>fruiting period>young fruit period.2.A correlation was established between freezing rate and cold resistance indexes,and the results showed that freezing rate was highly significantly correlated with conductivity,malondialdehyde and proline,with correlation coefficients of 0.79,0.69 and 0.59,respectively.3.The historical spatial and temporal changes of apple flowering in Ningxia from 1981 to 2022 simulated by the parallel model showed that both the beginning and end of flowering in Ningxia showed a highly significant trend of advancement,with a climate change tendency rate of-4.02 and-3.74 d/10a,respectively;the interannual trend of late frost days across Ningxia was quantified,indicating that the late frost days across Ningxia showed a significant trend of advancement,with a climate change tendency rate of-1.88 d/10a.10a,but apple flowering was more advanced and prone to frost damage4.Combined with the results of the late frost risk zoning of the main apple varieties planted in Ningxia:it is recommended to plant ’Gala’and ’Fuji’ apple varieties in Huinong,Pingluo and Yinchuan City in the north of Ningxia,Yanchi County and east of Concentric in the middle and Panyang in the south;’Fuji’ can also be planted in Qingtongxia,south of Lingwu City,Litong District and east of Hongshibao in the north;north of Concentric County in the middle.5.The results of the frost index test showed that ’Gala’ was more resistant to frost than ’Fuji’ in all periods,but a comprehensive zoning of frost hazard risk for both showed that ’Gala’ was at higher risk of frost than ’Fuji’.