No abstract

No abstract

The effect of Acibenzolar-S-methyl (ASM) and Rahnella aquatilis Ra39 against apple fire blight disease caused by Erwinia amylovora were tested as a possible alternative to streptomycin. In vitro studies, no inhibition effect against the pathogen was found when ASM was tested. Under greenhouse conditions, application of R. aquatilis Ra39 with the highly susceptible M26 rootstock resulted in a marked disease suppression. Application of ASM and strain Ra39 caused a high decrease of the disease, 82% and 58% respectively; this was correlated with a reduction of the growth of the pathogen within host plants up to 64% and 49.5% respectively. Further studies in the field under artificial infection condition during full bloom revealed that application of ASM and R. aquatilis Ra39 with Gala variety resulted in a control effect up to 21 and 29% respectively. In physiological studies, enhanced activities of PR-proteins (chitinase and β-1, 3-glucanase) were detected, which are well known as biochemical markers for systemic acquired resistance. Application of ASM to apple shoots caused the highest chitinase activity followed by strain Ra39. The enzyme activity was increased after 2, 4 and 6 days from application. In addition, ASM-treatment caused the higher β-1, 3-glucanase activity than strain Ra39. Maximum enzyme activity was recorded after 6 days from application and then decreased after 8 and 10 days from application.

Erwinia soft rot causes destructive and serious damage to many vegetable crops including potato in the field, transit and storage periods. The effect of certain cultural practices on the susceptibility of potato tubers to soft rot bacteria was studied and the results of this work can be summarised in the following: potato tubers harvested on 1 May first exhibited the highest disease incidence compared with those harvested on 15 May or 30 May. Harvesting on 15 June resulted in the lowest disease infection. The application of high levels of nitrogen fertiliser as urea (46.5%), ammonium nitrate (31%) and ammonium sulphate (20.5%) resulted in an increase of the susceptibility of potato tubers to bacterial soft rot disease. In contrast, the addition of phosphorous as superphosphate (15.5%) fertiliser caused the reverse effect. The addition of potassium as potassium sulphate (48%) alone at any of the tested levels showed no effect. The susceptibility of potato tubers to bacterial soft rotting disease was increased by increasing storage periods at 48C for 1, 2, 3 and 4 months. Spraying copper sulphate exhibited the highest decrease in soft rot incidence disease followed by manganese, zinc and iron. However, spraying of boron increased susceptibility to the disease. Potato tubers obtained from plants sprayed with copper and stored for different periods showed the lowest susceptibility to disease incidence. Tuber sprayed with zinc, iron, manganese and finally boron came next.

No abstract

No abstract

A B S T R A C TThe electrophoretic patterns of leaf water soluble proteins for 20 wheat varieties showed 17 bands. A new band of 60 kDa appeared in the patterns of the varieties Namangan and Kirsehir under drought stress. The protein bands of 23, 20 and 10 kDa were only presented in the pattern under drought stress for Xinjiang Uygur variety. The peroxidase isozymes showed four clear bands at loci of RF 0.075, 0.165, 0.25 and 0.75 which most of the varieties manifested more band intensities in the drought stress patterns than non-stressed plants. The superoxide dismutase showed three clear isozyme bands at loci of RF 0.28, 0.49 and 0.72. Out of the 20 varieties, 13 varieties manifested more band intensities in the drought patterns than the control and 4 varieties manifested the same band intensities under both conditions. The mean performance of agronomic traits for the varieties Sfaqis, Sids8, Giza164 and Trabulus gave high mean values for plant height, leaf area, number of spikes per plant and 100 grain weight, respectively under both conditions and showed high band intensities in the superoxide dismutase patterns under drought stress.