Hybrid vigor studies for different yield contributing traits in wheat under normal and heat stress conditions | Estudos de vigor híbrido para diferentes produtividades do trigo sob condições normais e de estresse por calor

English. Terminal heat stress is among one of the major constraints in wheat productivity in many countriesof the world including Pakistan. To combat this natural calamity,one hundred spring wheatgenotypes were assessed for heat stress tolerance under plastic sheet tunnel resulting in sevenparents with varied heat stress tolerance. The seven parents including tolerant, moderately tolerantand susceptible but high yielders were later hybridized in a 7×7 diallel fashion. Analysis of variancerevealed significant differences for all the studied traits.The heterosis and heterobeltiosis estimatesrevealed that thereisdesirable hybrid vigor in the current studies for all the traits evaluated.For grainyield maximum heterosis of 28.70% under normal and 27.02% under heat stress conditions wereobserved. Regarding heterobeltiosis it remained at 15.58% under normal and 13.62% under heatstress conditions. Similarly desirable negative results were obtained for relative cell injury%, days toheading and maturity and positive significant heterosis and heterobeltiosis was obtained for flagleaf area, biomass per plantand harvest index%. The cross combinations like Inqilab-91×Shalimar-88,Shalimar-88 × Maya/Pavon, Chenab-2000 × Punjab-85, Maya/Pavon × Chenab-2000, Shalimar-88 ×Uqab-2000 and Uqab-2000 × Maya/Pavonhave shown good hybrid vigor in terms of various traitsstudied. Suggestively, they may be further exploited following pedigree or bulk method to developheat tolerant wheat varieties because of their ability to perform well under normal and even diverseenvironments.

Portuguese. Estresse por calor está entre um dos maiores problemas quanto à produtividadede trigo em muitospaíses do mundo, incluindo o Paquistão. Para combater esta calamidade natural, cem genótiposde trigo de primavera foram avaliados quanto à tolerância ao estresse térmico sob túnel plástico,resultando em sete pares com tolerância variada a esse estresse. Os sete pares incluindo tolerantes,moderadamente tolerantes e suscetíveis, com exceção do mais elevado foramhibridizados em umesquema7 × 7, emformadialélica.A análise de variância reveloudiferenças significativas paratodasas características estudadas. As estimativasde heterosee heterobeltioserevelaram que hádesejávelvigor híbrido,nos estudosatuais, paratodas ascaracterísticas avaliadas.Para a produçãode grãoshouve heterosemáxima de28,70%sob condiçõesnormais e27,02%sob condições deestresse térmico. Quanto àheterobeltiose,manteve-se em15,58%normais e13,62%sob condições deestressetérmico.Da mesma forma,desejáveis resultados negativosforam obtidos para% em relaçãoà lesão celular, aos dias para crescimento e maturidade e positivaheteroseeheterobeltioseforamobtidaspara a áreada folha, a biomassa por planta eíndice de colheita%. AscombinaçõeshíbridascomoInqilab-91 ×Shalimar-88, Shalimar-88 ×Maya/Pavon, Chenab-2000 ×Punjab-85, Maya/Pavon×Chenab-2000, Shalimar-88 ×Uqab-2000 e Uqab-2000 ×Maya/Pavontêm mostradovigorhíbridobom em termos devárias característicasestudadas.Sugestivamente, eles podem sermais explorados,seguindométodo genealógicoou a granelpara desenvolvervariedades detrigotolerantesao calordadasuahabilidade de desenvolver-se bemem condições normaise atémesmo emdiversos ambientes. Hybrid vigor studies for different yield contributing traits inwheat under normal and heat stress conditionsAbstractTerminal heat stress is among one of the major constraints in wheat productivity in many countriesof the world including Pakistan. To combat this natural calamity,one hundred spring wheatgenotypes were assessed for heat stress tolerance under plastic sheet tunnel resulting in sevenparents with varied heat stress tolerance. The seven parents including tolerant, moderately tolerantand susceptible but high yielders were later hybridized in a 7×7 diallel fashion. Analysis of variancerevealed significant differences for all the studied traits.The heterosis and heterobeltiosis estimatesrevealed that thereisdesirable hybrid vigor in the current studies for all the traits evaluated.For grainyield maximum heterosis of 28.70% under normal and 27.02% under heat stress conditions wereobserved. Regarding heterobeltiosis it remained at 15.58% under normal and 13.62% under heatstress conditions. Similarly desirable negative results were obtained for relative cell injury%, days toheading and maturity and positive significant heterosis and heterobeltiosis was obtained for flagleaf area, biomass per plantand harvest index%. The cross combinations like Inqilab-91×Shalimar-88,Shalimar-88 × Maya/Pavon, Chenab-2000 × Punjab-85, Maya/Pavon × Chenab-2000, Shalimar-88 ×Uqab-2000 and Uqab-2000 × Maya/Pavonhave shown good hybrid vigor in terms of various traitsstudied. Suggestively, they may be further exploited following pedigree or bulk method to developheat tolerant wheat varieties because of their ability to perform well under normal and even diverseenvironments.