Abstract: 【Objective】 A field experiment was conducted to investigate the effects of deficit irrigation and nitrogen on tomato yield and reveal the growth index of group which affected tomato yield and finally obtained the optimal model of irrigation and fertilization in solar greenhouse in Northwestern China. 【Method】The experiment was carried out to explore the effects of different water and nitrogen supplies on tomato yield, and methods of canonical correlation analysis and grey correlation analysis were used to explore the correlation of tomato yield and growth character. The treatment comprised three levels of nitrogen (N1, 150 kg·hm^-2; N2, 250 kg·hm^-2; N3, 350 kg·hm^-2) and three levels of irrigation (I1, 0.5Ep; I2, 0.75Ep; I3, 1.0Ep), Ep is the cumulative evaporation of Ф20 cm standard evaporating dish. The treatments were replicated three times in randomized complete block designs. The irrigation amount of drip irrigation system was controlled by water meter, and watering frequency was 7 to 10 d. All rotten organic fertilizer, 50% of P fertilizer, 80% of K fertilizer and part of the nitrogen (50, 150, 250 kg·hm^-2) were applied before transplanting. The amounts of P and K fertilizer were same in each treatment. And the rest of P, K and N (100 kg·hm^-2) fertilizers which were divided into the same amount of two were applied during the first and third fruit enlargement periods with the irrigation water. 【Result】The tomato yield reduced after the first rise with the increasing of applied N rates nitrogen when irrigation water was the same. Tomato yield in I2 and I3 treatments were significantly higher than I1 treatment. The tomato yield presented a trend of quadratic parabola curve with the increasing of N-rate and irrigation water amount. The canonical correlation analysis showed that the increase of plant height and leaf area may cause the increasing of fruit weight and yield reduction and the increase of root length and dry matter lead improving yield and reducing fruit weight. The grey correlation analysis method showed the order of correlation between growth traits and yield was root, plant height, leaf area, dry matter and stem diameter. 【Conclusion】The W2N2 treatment was optimal with irrigation amount of 222.8 mm and nitrogen rate of 250 kg·hm^-2. Root length and dry matter could be used as important growth indexes to control yield.

Key words: water and nitrogen supply, yield, canonical correlation analysis, grey correlation analysis, growth character