SOWING DATE AND IRRIGATION EFFECTS ON PRODUCTIVITY AND WATER USE EFFICIENCY IN SUNFLOWER

Abiotic stresses represent a major impediment to crop productivity, especially in arid regions. Thus, over two years of 2014 and 2015, a field experiment was undertaken at El Nubaria region, Egypt to assess the productivity and water use efficiency (WUE) of sunflower as affected by planting dates (April 21, May 21, and June 21) and  irrigation levels (ET100%, ET85% and ET70%,). Results clarified that leaf chlorophyll a content was higher by sowing in May than in either April or June sowings, while leaf carotenoides of plant sown in May or June surpassed those sown in April. The minimal value of proline was obtained with sowing in May. Sowing in May increased plant height by 52.2 and 22.3 as well as LAI by 19.3 and 73.1% than sowing in April and June, respectively. The reductions in seed yield, oil yield and WUE amounted to 10.5 and 12.8, 13.7 and 18.3 as well as 11.8 and 9.8 % with April and June sowings, respectively, compared to May sowing. ET100% showed superiority over than ET85% and ET70% in improving sunflower yields and its attributes, but WUE did not affect. Sunflower sown in May and irrigated with ET100% gave the maximum values of seed yield and its attributes and WUE surpassing other interaction treatments. In June, WUE value increased under severe water deficit i.e. ET70% comparing to moderately water–stressed (ET85%) or well–watered conditions (ET100%)

SALT TOLERANCE INDEX OF TWENTY TWO SUGAR BEET (Beta vulgaris L.) VARIETIES AT EARLY STAGES OF GROWTH

A laboratory experiment was carried out to study the early growth response of 22 sugar beet (Beta vulgaris, L.) varieties to four salt concentrations of seawater i.e. 2000, 4000, 8000 and 16000 ppm. Germination and seedling growth traits (germination percentage (%), germination rate, seedling length (cm), seedling fresh weight (mg) and seedling vigor) were determined at the end of the experiment after 30 days from planting. The results showed that increasing the salinity level decreased the germination %, germination rate, seedling length, seedling fresh weight and seedling vigor of all sugar beet varieties under investigation to different extents. The results also clearly revealed that the response of the investigated varieties to salt concentrations was not the same, some varieties approved to be highly salt tolerant i.e. Soultan, Kawmira and Desprez; others were very sensitivity tolerant i.e. Helsiniki and LP16. However most of the investigated varieties were moderately salt tolerant. Results revealed clearly that the interaction effect between sugar beet varieties and salt concentrations was significant. This significant effect means that the tested varieties do not behave the same under the different levels of salinity stress