Adaptability of Helianthus annuus seedlings to crude oil pollution in soil and its improvement measures under salinization stress. Effects of chlorophylliniron on osmotic adjustment and activities of antioxidantive enzymes in cucumber seedlings under suboptimal temperature. The Sub cellular Chromium (Cr6+) Distribution and Tolerance Mechanism to Chromium Stress in Different Tolerant Brassica chinensis L. Cultivars