自然冷驯化对酿酒葡萄抗寒性的影响

Effect of natural cold acclimation on the cold resistance in wine grapes

【目的】冷驯化是植物获得抗寒能力的重要生理过程,研究葡萄自然冷驯化对低温的响应过程,对揭示葡萄抗寒力的形成过程及生理机制具有重要意义。【方法】以贺兰山东麓赤霞珠和北红1年生成熟枝条为试验材料,在2020—2021年,通过测定自然冷驯化过程中的生理生化响应指标,包括过冷却点SD、结冰点FP、可溶性糖含量、可溶性蛋白含量、电导率Con、Ca^(2+)含量、蔗糖Su含量、ABA含量等,构建了抗寒力指数反映葡萄枝条冷驯化过程,运用方差分析、t检验和数值模拟方法,分析葡萄生理生化参数对低温的响应过程,定量评价自然冷驯化过程对葡萄枝条抗寒性的影响。【结果】(1)最低气温是冷驯化过程的主导因子;低温引发葡萄枝条含水率降低,Ca^(2+)含量增加,改善枝条渗透调节能力;随着冷驯化温度降低,葡萄枝条蔗糖含量增加,抗寒性提高。枝条的ABA含量与日照时间(光周期)存在显著的正相关关系,但与低温关系不显著;降水(灌溉)降低了葡萄枝条抗寒力。(2)北红枝条抗寒力强于赤霞珠,年际间赤霞珠过冷却点SD和电导率Con均存在显著差异,北红过冷却点SD存在显著差异,其他因子差异不显著。(3)葡萄冷驯化过程是渐进累积的,葡萄抗寒力随着冷驯化气温的降低而增强,葡萄抗寒力指数与低温存在典型的Logistic非线性关系,在气温低于18.0℃时,葡萄启动冷驯化过程,抗寒力随温度降低而增强;在气温低于12.0℃后,葡萄抗寒能力迅速增大;在气温低于3.0℃时,葡萄枝条的抗寒力增大趋缓,至埋土前,葡萄抗寒力趋于最大。【结论】随着夏末日照时间缩短,葡萄枝条ABA含量逐步增加;低温在冷驯化过程中起主导作用,随着气温降低,葡萄枝条含水率下降,Ca和蔗糖含量增加。随气温降低,葡萄枝条抗寒力呈Logistic非线性渐进累积增大。

【Objective】Cold acclimation is an important physiological process for plants to increase cold resistance. The individual impact on the grape cold resistance from gene heredity and cultivation practice is quite stable, while the cold resistance of grape gained from cold acclimation in winter changes as the weather condition naturally varies with different years or places. Study on the responsive process of natural grape cold acclimation to low temperature and photoperiod is of great significance to reveal the formation process and physiological mechanism of grape cold resistance. It needs to build the relationship model between the cold resistance of grape and low temperature in order to analyze the low temperature indices for cold acclimation of grape.【Methods】In this paper, the annual ripe grape canes of Cabernet Sauvignon and Beihong at the eastern foot of Helan Mountain were taken and used as test materials to measure the physiological and biochemical response indicators, such as supercooling point,freezing point, soluble sugar, soluble protein, conductivity, Ca^(2+), sucrose, ABA, etc. Thereafter, the effect of natural cold acclimation on grape cold resistance was quantitatively evaluated by analyzing the response process of physiological and biochemical parameters to low temperature with the methods of variance analysis, t test and numerical simulation. The supercooling point and the freezing point were measured in the experimental frost box of SDX-20, in which the temperature sensors were fixed on the canes and data were taken once every 10 seconds. The supercooling point and the freezing point were determined according to the heat releasing process of tested canes. The dropping process of temperature was set as referring to the natural process with a decreasing rate of 3.0 ℃ · h^(-1) from the room temperature to-25 ℃. Conductivity was measured with DDSJ-308F conductivity meter firstly and then it was put in the boiling water for 30 minutes after it was sealed with glass stopper. After it cooled down to room temperature, the conductivity was measure again under the condition where it kept still after it was shaken slightly. The water content in canes was measured with the heating and weighing method.Ca^(2+) content was measured by following the microwave digestion method. Cane sucrose content was measured with the method of resorcinol colorimetry. The ABA concentration was measured with ABA test toolkit.【Results】The results showed that:(1) The lowest temperature was the dominant factor in the cold acclimation process;Under the low temperature condition, grapes could reduce the water content in canes, increase Ca^(2+) content, and improve the osmotic regulation ability of the canes;Under the low temperature condition, grapes could also improve the cold resistance by increasing the sucrose content in canes. There was a significantly positive correlation between ABA content in canes and sunlight duration(photoperiod), but not closely related to the low temperature. Precipitation(irrigation) also played a significant role in the cold resistance of grape canes so that it reduced cold resistance of grape canes.(2) The indictor of cold resistance, which was calculated from the absolute difference value of maximum and minimum supercooling point values, showed that the cold resistance of Beihong canes was stronger than that of Cabernet Sauvignon. However, there was no significant difference in cold resistance for the physiological indicators between Cabernet Sauvignon and Beihong varieties in the same year, like supercooling points, conductivity and cane water content. There were significant differences in the supercooling point and the conductivity of Cabernet Sauvignon between different years, and there was a significant difference in the supercooling point of Beihong but there were no significant differences for other indicators, like conductivity and cane water content.(3) The grape cold acclimation was gradually accumulated, and the grape cold resistance increased as the cold acclimation temperature dropped. There was a typical nonlinear logistic relationship between the grape cold resistance and the low temperature. When the temperature was lower than 18.0 ℃, grapes triggered the cold acclimation process. The cold resistance increased with the decrease of temperature. When the temperature was lower than 12.0 ℃, the grape cold resistance increased rapidly. When the temperature was lower than3.0 ℃, the increase of the cold resistance of grape canes slowed down, and the grape cold resistance reached the strongest before grapes were buried in the soil.【Conclusion】It was very complex physiological process of cold acclimation of grape as the intensity of cold acclimation was determined jointly by indicators, like grape gene heredity, photoperiod, low temperature, precipitation or irrigation and other environmental factors. The low temperature was a major determinate factor in the cold acclimation of grape. With the decrease of temperature at the beginning of autumn, the cold resistance of grape canes increased logistically rather than linearly and this process was evolving gradually and cumulatively.Sunshine was the secondary factor to play a role in the process of grape cold acclimation by inducing ABA generation. It seemed that temperature and sunshine independently played roles in the process of grape cold acclimation.