The Analysis Of Quality Indexes Of Wine Grape And The Study On Meteorological Condition's Impact On Some Qualities

Abstract: Based on the data of wine grape's sampling from field experiment and 6 provinces in northern China where mainly produce wine grape during 2004 and 2005, we analyzed the mainly weather factors and its key periods which affected the quality of wine grape such as total sugar, total acid, pH and tannin. Model between wine grape's qualities and meteorological condition had been established, and some meteorological indexes were brought forward for using. The main qualities were comprehensively evaluated by means of analytic hiberarchy process(AHP) and cluster methods. The main meteorological factors and period affecting the comprehensive quality were studied by using principal components and factor analysis. The results showed that:A. The key period effecting on wine grape is from July to August, the next is from turning-color period to mature .B. Meteorological factors which affect qualities of wine grape include ≥10℃ accumulated temperature before 30 days harvest (c t₃₀) , mean minimum temperature during pigmentation (Tn45), mean daily range of temperature during pigmentation (D₄₅), mean air humidity during pigmentation (U₄₅), rainfall during pigmentation (R₄₅), rainfall-heat coefficient during pigmentation (K₄₅) , rainfall during glowing season (R_g) , rainfall-heat coefficient during growing season (K_g), ≥10℃ accumulated temperature from July to August (ΣT_7-8), mean minimum temperature from July to August (Tn_7-8) , rainfall from July to August (R_7-8), sunshine from July to August (S_7-8) , rainfall-heat coefficient from July to August(K_7-8) and diurnal range during July to August D_7-8. Rainfall from July to August is the most important factor which effecte on total sugar content, the other factor such as minimum temperature , sunshine and rainfall-heat coefficient also play important role in sugar accumulating.C. When Σt₃₀>561℃.d, Tn₄₅.>13℃ U₄₅>47, ΣT_7-8>1395℃.d, Tn_7-8>16.5 ℃, total sugar content decreased with those weather factors. D₄₅>7.8℃ and D_7-8>7.6 ℃ are also the same. With R₄₅, R_g, K₄₅, K_g and K_7-8 increasing, total sugar content drop linearly. However, with S_7-8 increasing, total sugar content rise linearly. When R₄₅>76mm, R_7-8>130mm, K₄₅>1..65 and K_7-8>1.62, total sugar content is less thanl 70g/L. When the rainfall before 30 days harvest is >26mm, mean air humidity >64 and rainfall-heat coefficient >0.57, sugar/acid (S/A) is less than 32.D. Total acid content and the rainfall-heat coefficient before 30 days harvest formed a relationship of power function. Total acid content slowly increased with rainfall-heat coefficient increasing. If we want to get 5⁶g/L acid from wine grape, we should control K₃₀ 0.12⁰.63.E. Tannin content is related to the accumulated temperature from anthesis to reap, mean temperature in August, mean diurnal range from early September to reap, mean minimum temperature before 30 days harvest, and form exponential relationship with those weather factors. Tannin content formed parabola function relationship with sunshine duration in August.F. The pH rise with the increase of mean maximum temperature from anthesis to reap and evaporation from July to August.G. The locations with good quality are Yuma, Yuquanying, the third Guangxia base, Hedong which situated in the east of Helan mountains, Gaotai and Wuwei in Hexia corridor, as well as Shihezi region in Xinjiang. The grape quality in Yantai ,Penglai and Changli of Bohai sea is general.H. The comprehensive quality of wine grape are mostly affected by the rainfall, rainfall-heat coefficient during pigmentation, growing season and from July to August. Rainfal is the most important factor. The daily range of temperature during pigmentation and the mean relative humidity also play important role in quality forming. The minimum temperature during pigmentation is less important.