Drought is the major abiotic stress that limits the crop production at drastic level. Screening of tolerant accessions from available germplasm is the basic step in plant breeding. Sunflower is becoming popular and major oilseed crop in world but unfortunately it is drought sensitive. Screening in field has uncertainties due to the uncontrolled conditions, interaction of biotic and abiotic stresses and variability in environmental factors. Response of the sixty sunflower accessions to drought stress at germination and seedling stage was examined by using polyethylene glycol (PEG-6000) as drought simulator under laboratory. Normal and drought stress treatments i.e. T 1 = zero (control), T 2 =-1.33 MPa and T 3 =-1.62 MPa were developed by dissolving 0, 15 g and 20 g Polyethylene Glycol (PEG-6000) in 100 mL distilled water and a completely randomized design with three replications were used. Promptness, germination, seedling height, fresh weight, dry weight and stress indexes were determined to evaluate the response of sunflower accessions under normal and PEG simulated drought stress treatments. Principal component analysis was used to select the drought tolerant and sensitive accessions. The accessions 017583, A-75, A-79, 017592, G-33, A-48, A-23, G-61, HBRS-1 and 017566 were selected as drought tolerant while, CM-621, 017577, HA-124, HA-133, HA-342 and HA-341 were as drought sensitive. This study may be helpful for the comparison of drought indexes in a controlled experimental assay and for the identification of drought tolerant sunflower cultivars to be used in further breeding programs.
Drought stress is the most crucial factor among different abiotic stresses that limits crop production and its growth worldwide than any other stress. Screening of available germplasm is the basic tool for plant breeding. But unfortunately, there is no well-developed screening method of brassica. For this purpose, ten accessions of Brassica napus were grown in hydroponics and in vitro culture. For hydroponics, seeds of each accession were sown in polythene bags Fifteen days after sowing, seedlings were transplanted to the hydroponics at three drought stress levels T0= 0 (control), T1= 9% and T2= 18% of polyethylene glycol. Data were recorded on various seedling parameters after 15 days of transplantation. For in vitro culture seeds were grown in MS zero media and explants were used for callus culture. Three drought stress treatments of polyethylene glycol were applied which were used in previous experiment. Various drought tolerant related characters were measured after 21 days of callus formation. Recorded data of both experiments were subjected to analysis of variance and multiple comparison test. From this study it was concluded that most of the traits showed highly significant differences among the accessions in hydroponic than in in vitro culture. So, this study is very helpful in the next breeding program for the screening of brassica lines under drought stress.
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