Effect of Irrigation Escaping at Different Times on Growth and some Water Relations of Sunflower at North Nile Delta

TWO field experiments were conducted at El-Karada water
management station, Kafr El-Sheikh Governorate, Egypt, during
two successive seasons of 2008 and 2009. The present work was
carried out to evaluate the effect of irrigation escaping at different
times through the growing season on plant growth attribute of
sunflower grown at North Nile Delta, photosynthetic pigments, the amount
of water saving and irrigation water productivity. Randomized
complete block design with three replications was used. The irrigation
treatments included five treatments conventional irrigation along the
growing season every 15 days (T1), escaping irrigation at the age of 30
days from sowing = 3rd irrigation (T2), escaping irrigation at the age of
45 days from sowing = 4th irrigation (T3), escaping irrigation at the age
of 60 days from sowing = 5th irrigation (T4) and escaping irrigation at
the age of 75 days from sowing = 6th irrigation (T5). The results
showed that T4 had the highest values of crop water efficiency
(0.77 kg m-3) and irrigation water productivity (0.62 kg m-3) as an
the overall average of the two seasons. From the viewpoint of irrigation
water saving, T4 and T5 recorded the highest values of irrigation water
saving, with nearly the same amount, 511 and 519 m3/fed as an
average of the two seasons, respectively. Data also revealed that
irrigation escaping dates had a significant effect on leaf area, crop
growth rate, net assimilation rate and relative growth rate in both
growing seasons. The highest values of the abovementioned characters
were obtained under T3 followed by T4 in both growing seasons at the
second period (75-90) days after sowing. Also, chlorophyll a and b and
carotenoids concatenation were significantly affected by the irrigation
escaping dates and the highest values were recorded under T4 and T5 at
the age of 60 days after sowing in both seasons. It could be concluded
that the 5th irrigation (T4) is the best water management for sunflower
crop since it saved water by 18.2% relative to control treatment and
had the highest values of crop water use efficiency and irrigation waterproductivity.