Effects of Water Stress on Plant Growth and Reproduction of Sunflower ( Helianthus annus L .)

Abstract

Sunflower (Helianthus annus L.) productivity is strongly regulated by availability of water. In the present study we observed the growth and reproduction of sunflower due to 10 day water stress at different growth stages; vegetative, flowering and at maturity. The study consisted with a control, with continuous water supply one time in each day during every growth stages. Experiments were analyzed using Complete Randomized Design (CRD) with five replicates and repeated two times. Plant height, plant shoot length, plant root length, number of flowers, head diameter, seed wet weight and seed dry weight were significantly affected by the water stress. Plant shoot length of the control (163.4 cm) was significantly higher compared to other treatments. Water stress at vegetative stage significantly increased the number of flowers (8.4 flowers/plant) compared to the water stress at flowering stage (2.4flowers/plant) which observed with least number of flowers. The highest root length was observed (18.92 cm) at vegetative stage due to water stress and it was significantly different compared to maturity stage (11.8 cm) and the control (11.5 cm). Furthermore, water stress at flowering stage significantly reduced the head diameter of flowers (11.2 cm) and it lead to the reduction of final seed yield. However highest head diameter (17.9 cm) and seed wet weight (9.79g/plant) were recorded in control compared to all other treatments. It is concluded that water stress at different growth stages; vegetative, flowering and maturity stage have significant effects on the growth and reproduction of sunflower in different ways. Results also indicated that drought at flowering stage should be avoided to increase seed production of Sunflower.