Document Type : Original Article
Authors
1
Crop Sci. Dept., Fac. of Agric. El- Shatby, Alex. Univ., Egypt
2
Crop Sci. Dept., Fac. of Agric., Damanhour Univ., Egypt
Abstract
Two field experiments were conducted at the Experimental Farm of Damanhour Faculty of Agriculture, at El- Boustan, Damanhour University, Egypt during 2003/2004 and 2004/2005 winter growing seasons. This study aimed to evaluate sixteen bread wheat genotypes (locals and introductions) for drought tolerance under newly reclaimed area by two techniques; i.e., the canopy temperature (Tc) and the excised –leaf water loss (ELWL); and to compare these techniques with grain yield and kernel weight susceptibility indices. The study layout was a split- plot design, with four replicates. Three soil moisture levels of 25, 55 and 85 % of plant available water (AW) were allocated to the main-plots, whereas, the wheat genotypes were randomly assigned to the sub – plots. The obtained results showed that Tc ranged from 17.3 oC, at 85 % AW, to 22.4 oC at 25 %, AW in the first season, and from 16.7 oC, at 85 % AW,to 18.7 oC at 25 % AW in the second season. The local cultivar, Sids 7, had the warmest means of Tc (23.7 oC) and (19.4 oC ) at 25 % AW in the first and second season, respectively. ELWL ranged from 58.5%, at 85% AW, to 45.8%, at 25% AW, in the first seasons, whereas, it ranged from 44.3%, at 85% AW, to 36.4%, at 25% AW, in the second season. The local
cultivar, Sakha 61, had the minimum means for ELWL (32.4 %) and (32.8 %) in the first and second seasons,
respectively. The number of days to both heading and maturity declined with lowering soil moisture. An average delay of about three days in both heading and maturity was recorded between the most abundant soil moisture and the most stressed level of soil moisture in both seasons. Sakha 61 cultivar was the earliest genotype for heading, in the first season, and maturity in both seasons, while, Sids 7 was the earliest genotype for heading, in the second season, under the least and the most stressed environments. The average of grain yield for the two growing seasons significantly decreased from 5.38 tons/ha, in the most abundant soil moisture of 85 % AW, to 3.84 tons/ha in the most stressed soil moisture level of 25 % AW. Sakha 69 local cultivar and introduced Line 7 gave the highest means for grain yield (5.99 and 6.38 tons/ha ) at 85 % AW in the first and second seasons, respectively. Kernel weight significantly decreased from 53.65 mg, in the most abundant soil moisture of 85% AW, to 46.20 mg in the most stressed soil moisture level of 25% AW, over both seasons. The local cultivars, Gemmiza 7 and Gemmiza 9, recorded the highest means for kernel weight (59.0 mg) in the first season, while, Sakha 61 recorded the highest mean 63.3 mg in the second season at 85% AW. There was an insignificant negative correlation between Tc and both grain yield susceptibility index (Sy) and kernel weight susceptibility index (Sk) in the first season.
However, there was a significant positive correlation, in the second season, between both (Sk and ELWL) and (Sy and ELWL), while, there was a nonsignificant correlation in the first season.
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