WAASB-based stability analysis and validation of resistance sources to Plasmopara halstedii race-100 from the sunflower working germplasm for the semi-arid regions of India

Abstract

In sunflower, stable performance in a semi-arid region is an essential factor for obtaining high and stable seed as well as oil yield. Therefore, efforts were made to evaluate 28 sunflower genotypes including USDA, USA, France collection and germplasm maintained at ICAR-IIOR, Hyderabad under four semi-arid locations of India during 2021–2022. Screening of the selected genotypes for Sunflower Downy Mildew (SDM) which is important disease and cause losses upto 100% incited by Plasmopara halstedii race-100 in India was undertaken during previous years (2017-20) and validation experiment was conducted during 2021. WAASB (Weighted Average of Absolute Scores) and Multi-Trait Stability Index (MTSI) adopted for stability analysis. The analysis of variance from AMMI showed highly significant effects of the climate, genotypes, and their interaction. Only 56.13% which is lesser than 60% of total GEI variation was explained by first two PCs indicating the complexity of GEI and suitability of WAASB statistics. Based on WAASB study most stable genotypes identified for yield were GMU-494, LTRR-341, EC-601901 and GMU-481and GMU-494 for oil content. Based on WAASBY scores most stable genotype identified for yield were GMU-770 (96.76) and EC-178168-2 (96.53) and for oil content GMU-481(93.64), EC-601901(91.30). Simultaneous selection index MTSI has been employed for selecting high yielding genotypes with medium to high oil content. MTSI index identified ideal genotype EC-198078 which is closer to hypothetical ideotype with least MTSI index coupled with high WAASBY score and resistant reaction to SDM. Population structure based on 20 SSR markers depicted the change of Delta (k) value (k = 4) which suggests the four populations within the collection of 28 sunflower germplasm accessions. Based on multiple year screening we have identified and validated 10 resistance sources and three new sources of resistance to SDM for semi-arid region. Identified stable genotypes coupled with SDM resistance could be useful for the development of inbreds or can be used to develop superior populations in sunflower.