[Objective]This study was to reveal the photo-physiological properties and suitable climate conditions for potato growth,so as to improve potato quality and yield by making use of the climate resources in Ningxia Hui Autonomous Region,to intensively develop the special agriculture there to enhance the economic benefit of local people.[Method]Using CIRASⅠ-Portable Photosynthesis System,we measured the daily change of photo-physiological indices of potato and further analyzed their relationship with daily weather change,and investigated the impacts of climate factors including atmospheric temperature,humidity,CO2 concentration and light intensity on various physiological indices of potato at key growth stages（flowering stage and stem-swelling stage）.[Results]The results showed that（1） humidity in experimental field assumed a ＂ U＂ type cosine variation curve,while photosynthetically active radiation and atmospheric temperature presented a reverse variation trend;（2） atmospheric CO2 concentration was positively correlated with intercellular CO2 concentration of potato cells,both assumed double ＂ W＂ type curve for daily change;（3） during growth period of potato,in the sunny days with appropriate relative humidity,physiological indices including photosynthetic rate,transpiration rate and stomatal conductance presented similar change law with environmental factor photosynthetically active radiation,all appearing an ＂ M＂ type curve with double peaks and a typical midday depression;（4） midday depression caused by to higher light intensity always appeared simultaneously with the maximum and minimum of air temperature.[Conclusion]Our results provided scientific basis for the large scale production of potato in Ningxia Hui Autonomous Region.
[Objective] The aim was to study the effects of short-term high temperature stress on the photosynthesis of potato in different growth stages. [Method] Choosing powder potato named Longshu No.3 widely cultivated in Ningxia as test material,the changes of stomata conductance （Gs）,transpiration rate （Tr） and CO2 concentration difference between internal and external leaf chamber,net photosynthetic rate （Pn） and photosynthetic water use efficiency （WUE） in different growth stages under short-term high temperature were analyzed. [Result] During seedling stage,the hysteretic nature of net photosynthetic rate and CO2 concentration difference between internal and external leaf chamber of potato could be found under high temperature stress,while the change trends of stomata conductance and transpiration rate under high temperature stress were consistent to that at normal temperature,but stomata conductance and transpiration rate were higher than those at normal temperature,and CO2 concentration difference between internal and external leaf chamber affected net photosynthetic rate most obviously. During branching stage,the change trends of net photosynthetic rate,CO2 concentration difference between internal and external leaf chamber,stomata conductance and transpiration rate under high temperature stress and normal temperature were similar,but they changed abruptly and reached peak value at noon under high temperature stress,while there existed consistent variation of water use efficiency under high temperature stress and at normal temperature,and CO2 concentration difference between internal and external leaf chamber also affected net photosynthetic rate most greatly,next came transpiration rate. [Conclusion] High temperature stress affected the photosynthesis of potato in different growth stages,and it was more obvious during branching stage than seedling stage,while CO2 concentration difference between internal and external leaf chamber had the most important influence on net photosynthetic rate.
[Objective] The aim was to study the characteristics of the changes of extreme weather climate incidents such as severe drought in northwest and rainstorm in Xiji County of Ningxia. [Method] Precipitation anomaly percentage was applied to divide drought level and for statistics analysis. Seasonal index, linear tendency, and 5-years gliding average were used to reflect the trend of drought changes. The circulation wave of temporal sequence used polynomial expression to simulate the interannual variation scale. The positive part of the polynomial expression used bar chart to simulate interannual variation scale. [Result] The index of drought season from November to June was large. The general trend of annual drought was increasing. The drought of interannual scale was most serious around 1977, about 15 and 20 years. The drought in recent years went up. The general situation of drought, interannual scale and changes of interannual scales from March to May and from September to October were discussed. Based on the weather at 500 hPa, the first rain in Xiji and the drought-turning-into-rain situation were classified. [Conclusion]These may provide reference value to the prevention and mitigation of drought.
