Yield And Quality Responses Of Citrus (Citrus Reticulate) And Tea (Podocarpus Fleuryi Hickel.) To Compound Fertilizers

Zhejiang Province lies in Southeast China where the monsoon climate has relatively high annual mean temperature and large annual mean rainfall, favors the mineralization of soil organic matter and minerals, and thus increases the risk of nutrients leaching, which has become one of the predominant degradation processes of soil fertility (Sun et al, 2000). Citrus (Citrus reticulata) and tea (Podocarpus fleuryi Hickel.) are two important economical crops in the region. Best fertilization strategies to increase yields and quality of these two crops are of great significance to economical growth.Citrus is perennial and evergreen plant with many flowers and requires a large amount of nutrients. Applying proper compound fertilizers has been shown to enhance the growth, increase yield and improve quality of citrus (Yu et al., 2000;Wen and Cai, 2001;Chen, 1990).Tea is a perennial evergreen shrub belonging to the Camellia genus of the Theaceae family (Ravichandran, 2002).Tea is one of the most popular beverages consumed in the world (Ohe et al., 2001). Green tea, which is the favorite type consumed in Japan and China, has been increasingly used also in Western countries in recent years (Majchrzak et al., 2004).Farmers usually apply urea for tea production, and apply organic manures for P, K and Mg nutrition. In fact, tea plants need large amounts of N, P, K and Mg for growth. The deficiency of these nutrients could drastically adversely affect yield and quality (Zheng et al, 1999;Yu et al, 1997;Li and Pan, 1991). Nutrient deficiency in soils and poor fertilization are two causations for low yield and quality of teas (Yuan et al, 2000). In order to study the effects of different nutrient ratio and fertilization methods of compound fertilizers on yields, quality and economical profits of citrus and tea, three years' field experiments were conducted.The results in the citrus experiment indicated:1. Compared with the control, application of compound fertilizers not only increased available P, K contents in soil and enhanced P, K and Mg absorption byplant, but also improved greatly N absorption by plant, which was advantageous to citrus plant growth.2. Compared with the control, application of compound fertilizers could improve the quality of citrus, fruit weight, dissolvable solid matter contents, soluble sugar contents and Vitamin C contents in citrus fruits universally rose significantly, however, titratable acidity decreased. It was found that not only the S/A ratio (the ratio of sugar content to titratable acidity) of citrus fruits rose, but also the flavor became better, and the shape became more beautiful when compound fertilizers are used.3. Compared with the control, application of compound fertilizers increased the yields and economical profits of citrus and tea greatly. In conclusion, in experimental sites, the Treatment 4 for citrus (Table 1) was more effective than the others, then was the Treatment 2.The results in the tea experiment indicated:1. Compared with the control, application of compound fertilizers not only increased available P, K contents in soil and enhanced P, K and Mg absorption by plant, but also improved greatly N absorption by plant, which was advantageous to tea plant growth.2. Compared with the control, the quality of tea was improved by application of compound fertilizers through increasing tea polyphenol contents, total amino acid contents and soluble substance contents, while reducing the P/A ratio (ratio of tea polyphenol content to total amino acid content) of tea leaves.3. Compared with the control, application of compound fertilizers increased the yields and economical profits of tea greatly. In conclusion, in experimental sites, the Treatment 3 for tea (Table 2) were more effective than the other treatments.