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Inheritance Mechanisms Of Drought Tolerance And Yield Attributes In Wheat Under Irrigated And Rainfed Conditions

Rabbani, Ghulam (2009) Inheritance Mechanisms Of Drought Tolerance And Yield Attributes In Wheat Under Irrigated And Rainfed Conditions. PhD thesis, University of Arid Agriculture, Rawalpindi .

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Abstract

Punjab province is the major wheat producing tract of the country and one-third of its total cultivated area is rainfed where rainfall is erratic and uncertain. This situation is a major limiting factor for wheat production. Understanding of genetic mechanism of drought tojerance is imperative to develop suitable wheat genotypes for these areas. Forty wheat genotypes possessing diverse genetic makeup were tested in field under medium rainfall conditions at Barani Agricultural Research Institute (BARI), Chakwal and under high rainfall conditions at Pir Mehr Ali Shah, Arid Agriculture University, Rawalpindi. From these genotypes, eight contrasting genotypes (four each drought tolerant, Inqlab-91, MAW-1,Saleem-2000 and 2KC033 and drought susceptible No. 2495, 3C061, 3C062 and 3C066) were screened out on the basis of more/less yield reduction and were crossed in all possible combinations at BARI, Chakwal. F1 hybrids alongwith parents were grown at BARI, Chakwal under two conditions; irrigated and rainfed. Data were recorded for drought and yield related attributes and were analyzed to understand the genetic mechanisms of these traits. Results of genetic analysis and graphical analysis revealed that over dominance action of genes for number of fertile tillers per plant, number of grains per spike, 1000 grain weight, number of spikelets per spike, grain filling period, grain filling rate, grain yield per plant, dry weight at maturity, harvest index and protein contents remained unchanged under irrigated and rainfed conditions. Similarly additive type gene action was observed for peduncle length, plant height and number of days to maturity under both irrigated and rainfed conditions. Over dominance type of gene action for number of days to heading and flag leaf area under irrigated conditions changed to dominance under rainfed and for spike length under irrigated conditions changed to additive under rainfed conditions. Genrtic effects controlling for the expression of yield and yield components shifted due to the changed environments. Graphic presentation indicated that parental genotypes shifted their positions from recessive to dominant or the midway or vice versa, for the same trait in response to environmental change. It was noted from the graphs that gene control of certain traits was also modified due to change in environment. Recessive gene control for number of days to heading, grain yield per plant and harvest index under irrigated conditions changed to dominant gene control under rainfed while dominant gene control of 1000 grain weight under irrigated condition changed to recessive under rainfed condition. However, it was also found that gene action for many characters remained unchanged over environments. Genotypes Inqlab-91 and MAW-1 displaying similar constitution under both sowing conditions showe that these contained stable genes for those particular characters. The screened genotypes and breeding material so generated will serve as raw material for the breeders to develop high yielding and drought tolerant wheat varieties for the rainfed areas

Item Type:Thesis (PhD)
Uncontrolled Keywords:Mechanisms, Inheritance, Drought, Tolerance, Yield, Attributes, Irrigated, Rainfed, Conditions, Cultivated, Dominance, Diverse, Genetic, Environmental, Recessive, Gene, Grains
Subjects:Agriculture & Veterinary Sciences(a) > Agriculture(a1)
ID Code:6419
Deposited By:Mr. Javed Memon
Deposited On:30 Jun 2011 11:32
Last Modified:30 Jun 2011 11:32

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