Physiological Characteristics, Yield and Yield Attributes of Some New Bread Wheat (Triticum aestivum L.) Cultivars as Affected by Irrigation Regimes under Sprinkler Irrigation System

TWO FIELD experiments were carried out in the Experimental Farm at Ismailia Agricultural Research Station, El-Ismailia Governorate, Egypt during two successive winter seasons (2009/2010 - 2010/2011). The experiments determined the effect of three irrigation regimes (I-1,I-2 and I-3) on some new bread wheat cultivars (Giza 168, Sakha 94, Sids 12 and Gemmeiza 11) under sprinkler irrigation system in sandy soils. Severe water stress was induced by irrigation every three weeks throughout the season (I-3) using a sprinkler irrigation system in sandy soil conditions. This treatment significantly decreased plant height (55.71 cm), days to 50% heading (84.5 day) and maturity (115.65 day), relative water content (41.09%), transpiration rate (105.65 mg H2O/g FW/h), number of spikes/m(2)-(220.06), number of grains/ spike (24.57), 1000-grain weight (26.83 g) and grain yield (3.69 ardab/fed) but increased proline content. Lesser reductions were observed for treatments with irrigation every two weeks (I-2) relative to irrigation every week (I-1) throughout the season. These effects were present for both seasons and in a combined analysis. Gemmeiza 11 had the highest plant height (66.66 cm), relative water content (55.38%), and 1000-grain weight (35.2 g). It had a transpiration rate of 132.23 mg H2O/g FW/h. Giza 168 had the highest number of spikes/m(2) (263.5) and number of grains/spike (41.03), as well as transpiration rate (134.23 mg H2O/g FW/h). Sids 12 had the highest number of spikes/m(2) (263.15) and grain yield (6.33 ardab/fed). Meanwhile, Sakha 94 was latest in heading and maturity, gave the highest proline content (18.53 mu moles proline/g FW) and the lowest transpiration rate (121.3 mg H2O/g FW/h). Gemmeiza 11 and Giza 168 followed by Sids 12 were tolerant to water stress and Sakha 94 was the most sensitive. Physiological characters, i.e., relative water content (RWC), transpiration rate and proline content may be playing a role in the tolerance of wheat plants to water deficit. It is suggested that breeders can use these characters as selection criteria for drought tolerance.