Sunflower response to a range of soil water contents.

摘要

The effect of different water stress intensities on the fraction of carbon partitioned to the head was investigated in sunflowers cv. Viki. Water consumption, yield and its components, leaf area, and net photosynthesis were also measured. Plants were grown in plastic pots in a greenhouse. At the eight-leaf stage, water stress was imposed and held until physiological maturity. Three levels of stress intensity, defined by pre-dawn leaf water potential, were studied. Water stress increased harvest index and water-use efficiency. In stressed treatments, leaf area decreased through a drop in leaf expansion and net photosynthesis declined linearly with leaf water potential. At anthesis, water stress induced an increase in the fraction of assimilates partitioned to the head. The relationship between net photosynthesis and leaf water potential was not affected by the level of stress intensity and the allocation of photosynthates to the head was similar in all stressed treatments. Thus, in this study it is concluded that sunflowers responded to water stress in the same way at all stress intensities.