红阳猕猴桃生长发育期树干液流特征及其与环境因子的关系

Characteristics of trunk SAP flow and its relationship with environmental factors during growth and development in Hongyang kiwifruit

【目的】分析红阳猕猴桃不同生育期树干液流特征及气象因子,探索猕猴桃耗水变化规律及环境影响因子,为猕猴桃的合理灌溉提供科学理论依据。【方法】于2020年3月1日至8月31日,采用热扩散式液流探针法对5年生的红阳猕猴桃树干液流测定的同时监测环境因子。【结果】(1)猕猴桃日耗水变化主要呈“低-高-低”变化趋势,表现为“昼高夜低”,夜间存在微弱耗水;不同生育期猕猴桃树干液流启动时间存在差异。(2)猕猴桃日均耗水量在不同的生育期存在差异(p<0.05)。不同生育期日均耗水量为:果实膨大期>果实成熟期>开花坐果期>萌芽展叶期。(3)不同生育期猕猴桃树干液流日变化与太阳辐射、气温、风速、土壤温度和土壤湿度呈显著正相关,与相对湿度呈显著负相关。(4)猕猴桃不同天气条件下树干液流量日变化为:晴天>阴天>雨天。【结论】猕猴桃耗水量受环境因子和生长特性影响,不同生育期耗水量存在差异,为不同生育期耗水量制定合理的蓄水措施和灌溉方式提供重要依据。热扩散式液流探针法可快速便捷测定猕猴桃耗水量,可应用到果树耗水测定中,节约耗水测定时间。

【Objective】At present, the situation of water shortage in China is becoming more and more serious, especially in the arid areas of northwest China. The lack of water resources has been considered as a serious obstacle to agricultural development. With the change of industrial structure, the planting area of fruit industry in China is increasing, but the irrational use of water resources leads to a sharp increase in water consumption. Therefore, how to make effective use of limited water resources and produce high-quality, stable and high-yield fruits with increasing the income of local farmers and promoting the effective circulation of ecological environment has become a scientific problem to be solved urgently. In view of the large spatial and temporal differences in rainfall in Miluo Town, Shuicheng County, Guizhou province, the water consumption and environmental factors of kiwifruit in different growth stages were measured and systematically analyzed. The water consumption of kiwifruit in different growth stages was discussed in order to provide scientific basis for water management and rational utilization of kiwifruit in this district.【Methods】The experiment was carried out from March 1 to August31, 2020. The flow rate of stem fluid of 5-year-old kiwifruit Hongyang was measured by thermal diffusion flow probe method, and the environmental factors were monitored synchronously by small meteorological stations. After selecting the representative sample wood, the compass was employed to determine the sample wood north direction, the dead skin at the diameter with breast height(1.3 m) was scraped off, and sodium hypochlorite was used to clean out the drill, which was fit to the sensor hole.The probe was inserted into it, paying attention to the depth of the probe, and plasticine was applied to seal the joints after insertion, and tools such as foam and tape were used to fix the probe. Finally, the outer layer was wrapped around the PVR shield and sealed with waterproof tape. The seal was coated with glass glue to prevent water from entering, which worked normally after connecting the power supply. Average data were calculated and stored for every 30 min. The measurement method was set for point continuous observation.【Results】Daily average water consumption at different growth stages was as follows: the fruit expansion period(3.02 kg) > fruit maturity period(2.94 kg) > flowering and fruit setting period(0.99 kg) > bud break and leaf expansion period(0.77 kg). The daily maximum average water consumption in fruit expansion period was 4 times more than that in bud break and leaf expansion period. It was worth noting that the daily water consumption of kiwifruit mainly showed a trend of“low-high-low”. The daily maximum average water consumption at the fruit enlargement growth stage was 4 times more than that at the bud break and leaf expansion stage, and notably, the daily water consumption of kiwifruit mainly showed a“low-high-low”trend. The water consumption of kiwifruit mainly occurred between 8:00 and 16:00, which represented“high in the day and low in the night”, and there was a less water consumption at night. In terms of the monthly scale, the water consumption of kiwifruit increased gradually from March to July, reaching the maximum in July, while slightly decreasing in August, and the overall trend was as follows: July(90.60 kg)>August(86.96 kg)>June(66.20 kg)>May(53.35 kg)>April(41.21 kg) >March(25.29 kg). The total water consumption at different growth stages was as follows: The fruit swell stage(326.33 kg) > the fruit maturing stage(88.13 kg) > the flowering and fruit-setting stage(24.71 kg) > the bud break and leaf expansion stage(18.36 kg), and the maximum water consumption at the fruit swell stage was 17.78 times more than that at the fruit maturing stage. There was a significant correlation between SAP flow rate and environmental factors at different growth stages of kiwifruit. In addition, the solar radiation, air temperature, wind speed, soil temperature and soil moisture were significantly and positively correlated with diurnal variation of SAP flow of kiwifruit at different growth stages, while negatively correlated with relative humidity. Furthermore, the diurnal variation trend of environmental factors such as solar radiation, air temperature, wind speed and soil temperature was similar to that of SAP flow rate of kiwifruit. Moreover, taking RN, VPD, VT and TS as independent variables and SAP flow rate as dependent variables, the multiple regression analysis was conducted, and the bud break and leaf expansion stage was obtained: F=60.985+0.055 Rn+11.844 VPD+1.043 VT-3.119 Ts(R2=0.918), the flowering and fruit-setting stage was F=-301.524+0.336 Rn-77.366 VPD+2.529 VT+22.777 Ts(R^(2)=0.962), the fruit swell stage was F=643.830+0.124 Rn+26.082 VPD+1.683 VT+29.093 Ts(R^(2)=0.968), and the fruit maturing stage was F=-1955.991-1.845 Rn+175.061 VPD+17.850 VT+81.869 Ts(R^(2)=0.973). The coefficient of determination for the fit of the four factors was 0.973. It was worth noting that the four environmental factors of RN, VPD, VT and TS had a good explanation for the changes in SAP traffic. There were differences in SAP flow rate under different weather conditions during the prime period of kiwifruit. In addition, the daily variation of SAP flow was as follows: Sunny day > cloudy day > rainy day. The SAP flow rate of kiwifruit trunk showed a single or bimodal trend of“low-high-low”on cloudy days and sunny days, while it showed a multi-peak pattern on rainy days, which was mainly caused by the environmental factors that fluctuated greatly in rainy days. Furthermore, with Rn, VPD, VT and TS as independent variables and SAP flow rate as dependent variable, the multiple regression analysis was carried out. The fitting equation under sunny conditions was F=-943.776+0.260 Rn+49.647 VPD+1.7558 VT+42.698 Ts(R^(2)=0.956), and that under overcast conditions was F=-476.655+3.643 Rn+228.831 VPD+0.566 VT-1.854 Ts(R^(2)=0.674). The fitting determinants of sunny, cloudy and rainy days were 0.965, 0.751 and 0.674, respectively. The fluctuation of environmental factors was the largest in rainy days, while the fitting determinants were the lowest. 【Conclusion】According to the multiple relationships among water consumptions in different growth stages of kiwifruit, the water consumption ratio in different phenological stages was determined synthetically. Combined with soil moisture index, the corresponding water storage facilities were established, and the problem of uneven spatial and temporal distribution of rainfall was compensated.