الفهرس 
ACKNOWLEDGMENTOnly 14 pages are availabe for public view
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Abstract
This study was carried out during the two growing seasons of 2016/2017 and 2017/2018 at two locations including Assiut (Agronomy Dept. Experimental Farm (clay soil)) and El-Ghorieb (sandy calcareous soil), Faculty of Agriculture, Assiut University. This work aims to evaluate thirty two bread wheat genotypes of diverse origin under normal irrigated (six irrigations) and water stress (three irrigation) for yield and related traits. Furthermore, the physiological traits were studied i.e. proline, sugars, proteins, and amino acids. In all experiment a strip plot design with three replications was used.
The results obtained could be summarized in the following:
I- Performance of bread wheat genotypes at Assiut location
A- Agronomical traits
Separate and combined analyses of variance in the two seasons and over the two seasons revealed significant or highly significant differences between each of irrigation treatments (normal and water stress), genotypes, and irrigation x genotypes interaction for all traits agronomical, except the irrigation x genotype interaction for 100 grain weight in first season was insignificant.
Plant height
The water stress caused decrease in plant height in each season and over two seasons. The reduction in plant height due to water stress in the first, second and over two seasons means were 7.8, 10.7 and 9.2%, compared to normal irrigation, respectively. The tallest genotypes were Assiut 401 for normal and water stress over the two seasons. The best tolerant genotypes to drought were C138 (0.24) and C109 (0.35).
Spike length
Water stress cause decrease in spike length compared to normal irrigation in each and over the two seasons. The reduction due to water stress in the first, second seasons and combined means were 5.48, 11.67 and 8.53%, compared to normal irrigation, respectively. The longest spike was recorded for Sel-542 under normal and water stress irrigations. Drought susceptibility index recorded fifteen, seventeen, and nineteen genotypes were less susceptible or tolerance to drought in the first, second and over the two seasons, respectively.
Number of spikes/row
The reduction in number of spikes/row to water stress in the first, second seasons and combined means were 27.02, 18.89 and 23.62% compared to normal irrigation, respectively. Number of spikes/row of the different genotypes differed in rank from normal and water stress irrigation and from season to season. Drought susceptibility index indicated that sixteen, seventeen and eighteen genotype were less than unity in first, second, and over the two seasons, respectively and considered tolerant to drought.
Number of spikelets/spike
The reduction in number of spikelets/spike due to water stress were 5.70, 5.29 and 5.51% in the first, second seasons and over two seasons, respectively, compared to normal irrigation. Generally water stress reduction number of spikelets/spike for all genotypes. Fifteen, twenty-two and eighteen genotypes could be considered tolerant to drought in first, second and over the two seasons, respectively.
Grain yield/plant
The reduction in grain yield/plant due to water stress were 26.62, 34.35 and 30.44% in the first, second and over two seasons, respectively compared to normal irrigation. Twenty one, nineteen and twenty genotypes could be considered tolerant to drought in first, second and over the two seasons, respectively (The DSI less than unity).
Grain yield/row
The reduction in grain yield/row due to water stress were 40.68, 29.37 and 35.81% compared to normal irrigation in the first, second and over two seasons, respectively. Eleven and nine genotypes were significantly surpassed the mean average of grain yield/row under normal and water stress irrigation, respectively over the two seasons. Drought susceptibility index indicated that eighteen, twenty and eighteen genotypes were tolerant to water stress in first, second and over two seasons.
The 100 grain weight
The reduction in 100 grain weight due to water stress in the first, second seasons and combined means were 9.45, 12.07 and 10.8%, respectively, compared to normal irrigation. The combined means revealed five and two genotypes were significantly surpassed the average 100 grain weight under normal and water stress irrigation, respectively. Drought susceptibility index were less than unity for seventeen in first and fifteen in both second and over the two seasons.
B – Physiological traits
Separate and combined analyses of variance for the physiological traits i.e. proline, sugars, proteins, amino acids revealed significant or highly significant differences between normal and stress water for all physiological traits. Also, among the evaluated genotypes, as well as, mean squares due to irrigation treatment x genotypes interaction are also significant differences for all physiological traits.
Proline content
Proline content of all genotypes was increased by water stress. The increase accounted 55.44, 57.30 and 56.34% compared to normal irrigation in the first, second seasons and combined means, respectively. Drought susceptibility index were less than unity for fourteen genotypes and those tolerant to drought over the two seasons.
Sugars
Soluble sugars was increased by water stress in all genotypes. This increased over all genotypes accounted 35.30, 41.97 and 38.02 from normal irrigation in the first, second and over two seasons, respectively. Drought susceptibility index of sugars indicated that fourteen genotypes tended to be tolerant to drought under combined seasons.
Soluble proteins
Soluble proteins contents of all genotypes were higher under the water stress than those of the normal irrigation in each season and over two seasons. The increase in soluble proteins due to water stress in the first, second seasons and combined means were 35.36, 19.88 and 24.52% compared to normal irrigation over all genotypes. Drought susceptibility index indicated that ten genotypes tended to be tolerant to drought under each season and combined means.
Total free amino acids
Total free amino acids of all genotypes were higher under the normal irrigation than those of the water stress treatment. It was decreased by 35.6, 49.2 and 43.07% under water stress compare to normal irrigation in the first, second and over the two seasons, respectively. Drought susceptibility index indicated that twelve genotypes tended to be tolerant to drought under each season and over the two seasons.
II- Performance of bread wheat genotypes at El-Ghorieb location
A- Agronomical traits
Separate and combined analyses of variance in each season and over the two seasons revealed significant or highly significant differences between normal and water stress irrigations for all agronomical traits. Also, among genotypes and interaction between irrigation treatment x genotypes for all agronomical traits, except for 100 grain weight among genotype in second season and genotypes x irrigation interaction in first season and combined mean.
Plant height
The reduction in plant height due to water stress in the first, second seasons and combined means were 21.75, 12.91 and 17.67% compared to normal irrigation, respectively. The tallest genotype was C118 and shortest was C103 under combined average. Drought susceptibility index indicated that fifteen, fifteen and nineteen genotypes tolerant to drought and gave less then unity for first, second and over the two seasons, respectively.
Spike length
Water stress cause slight decrease in spike length compared to normal irrigation in first season (12.20 and 11.24 cm) second season (11.95 and 10.0 cm) and combined means (11.63 and 10.62 cm) over all genotypes. The reduction due to water stress in the first, second seasons and combined means were 7.86, 9.51 and 8.64% compared to normal irrigation, respectively. Drought susceptibility index indicated that eighteen, twenty and seventeen genotypes in first, second and over two seasons, respectively tended to be tolerant to drought.
Number of spikes/row
The reduction in number of spikes/row due to water stress in the first, second seasons and combined means were 51.63, 57.45 and 53.37% compared to normal irrigation. The genotypes C109, C138 and C144 were the best under water stress in both seasons. Drought susceptibility index indicated that seventeen, thirteen and fifteen genotypes proposed DSI less than unity and these considered tolerant to drought in the first, second and over two seasons, respectively.
Number of spikelets/spike
Water stress reduced number of spikelets/spike by 6.44, 9.79 and 8.02% compared to normal irrigation in the first, second and combined over the two seasons, respectively. Mubarak genotype was the best one under water stress over both seasons. Drought susceptibility index recorded twenty two, sixteen and nineteen genotypes less than unity in the first, second and over the two seasons, respectively.
Grain yield/plant
The decrease by water stress accounted for 36.63, 33.63 and 35.12% from normal irrigation in the first, second and combined over the two seasons, respectively. Under normal irrigation one, five and three genotypes gave significant grain yield/plant than the best check cultivar Sids-12 in the first, second and over two seasons, respectively. Drought susceptibility index indicating that eighteen in the first season, and seventeen in both second and over the two seasons which gave DSI less than unity.
Grain yield/row
The reduction in grain yield/row due to water stress in the first, second seasons and combined means were 56.01, 27.20 and 44.84% compared to normal irrigation, respectively. Some genotypes (i.e. C146) gave significantly grain yield/row than the check cultivars under normal and water stress irrigation. Drought susceptibility index indicated that sixteen, twenty one and eighteen genotypes were tolerant to drought in the first, second and over the two seasons, respectively.
100-grain weight
The reduction in 100 grain weight due to water stress in the first, second seasons and combined means were 9.45, 41.17 and 24.32% compared to normal irrigation, respectively. Ten genotypes were significant and surpassed the check cultivar Giza-168 over two seasons. Drought susceptibility index indicated that twenty, sixteen and nineteen genotypes were tolerant to drought in the first, second and over the two seasons, respectively.
B – Physiological traits
Separate and combined analysis of variance for the physiological traits (i.e. proline, sugars, proteins, and amino acids) revealed significant or highly significant differences between normal and water stress irrigation in all physiological traits, except protein content in second season, also, among the evaluated genotypes. As well as mean squares due to irrigation treatment x genotypes interaction are also significant differences for all physiological traits.
Proline contents
The increased in proline content due to water stress in the first, second seasons and combined means were 50.07, 9.84 and 60.44% compared to normal irrigation, respectively. Drought susceptibility index revealed that fifteen genotypes could be recorded as drought tolerant.
Soluble sugars
The increased in soluble sugars due to water stress in the first, second seasons, and combined means were 48.78, 31.43 and 39.49% compared to normal irrigation, respectively. Drought susceptibility index indicated that twelve genotypes were tolerant to drought under over two seasons.
Soluble proteins
The increased in soluble proteins due to water stress in the first, second seasons, and combined means were 22.54, 23.51 and 22.94% compared to normal irrigation, respectively. Drought susceptibility index indicated that sixteen genotypes were tolerant to drought over the two seasons.
Total free amino acids
The total free amino acids was decreased by 45.9, 41.8 and 43.8% under water stress compared to normal irrigation in the first, second and over the two seasons, respectively, under all genotypes. Eleven genotypes tend to be tolerate to drought in each and over the two seasons.