Evaluation of spring barley genotypes tolerance to drought stress and aphid infestetion [electronic resource].

Includes reference.

Thirty four barley genotypes plus two local barley (check) were tested for resistance to drought stress and corn leaf aphid, Rhopalosiphum maidis (Fitch.) infestation under field conduction at Sohag governorate during 2004/2005 and 2005/2006 seasons. Results show that, the irrigation intervals significantly affect the population densities of Rhopalosiphum maidis and the prolonged of interval of irrigation to four week caused a significant decline in aphid population. The results obtained reveled that the corn leaf aphid, Rhopalosiphum maidis (Fitch.) appeared from January then increased gradually to reac:l its maximum level of abundance during last week of March during both seasons. The genotypes were different in their sensitivity to the infestation with Rhopalosiphum maidis and it divided to four groups, the first one was highly resistance, includes (1,3, 4, 21, 23, 34 and Giza 128) and the second group was moderately resistance includes (33 and Giza 127), and the third group was susceptible includes (2, 5 and 6), and the fourth group was highly susceptible includes the remaining barley genotypes. TIle genotypes (1, 3, 4, 21, 23, 33 34, Giza 127 and Giza 128) achieved high yield under normal and regime irrigation with potentiality high resistance to drought stress. The genotypes (4, 7, 13, 15. and 29) give the highest No. of kernels/spike. Genotypes (13, 14, 20, 22 and Giza 128) give the highest number spikes/plant. The highest 1000 kernel weight was obtained by genotypes (3,8,26,30 and Giza 128). Yield was negative and strong correlation with, number of aphid (-0.87** and -0.84**) under normal and drought stress. The correlation between nonnal irrigation and aphid densities during two seasons was strong and negative (-0.868**). Strong negative correlation (-0.854**), between drought stress and the aphid densities were detected.

Summary in Arabic.

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