Identification of quantitative trait loci associated with iron deficiency chlorosis resistance in groundnut ( Arachis hypogaea )

Iron deficiency chlorosis is an important abiotic stress affecting groundnut production worldwide in calcareous and alkaline soils with a pH of 7.5–8.5. To identify genomic regions controlling iron deficiency chlorosis resistance in groundnut, the recombinant inbred line population from the cross TAG 24 × ICGV 86031 was evaluated for associated traits like visual chlorosis rating and SPAD chlorophyll meter reading across three crop growth stages for two consecutive years. Thirty-two QTLs were identified for visual chlorosis rating (3.9%–31.8% phenotypic variance explained [PVE]) and SPAD chlorophyll meter reading [3.8%–11% PVE] across three stages over 2 years. This is the first report of identification of QTLs for iron deficiency chlorosis resistance- associated traits in groundnut. Three major QTLs (>10% PVE) were identified at severe stage, while majority of other QTLs were having small effects. Interestingly, two major QTLs for visual chlorosis rating at 60 days (2013) and 90 days (2014) were located at same position on LG AhXIII. The identified QTLs/markers after validation across diverse genetic material could be used in genomics-assisted breeding

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Not AvailableUnlike kharif sorghum being dominated with hybrids, post-rainy sorghum growing areas are mainlycultivated with varieties especially landrace selections. Contrary to kharif hybrids, the heterosis in rabi hybrids is insignificant as the landraces are used in the development of hybrid parents.Most of the varieties developed by breeders in self-pollinated crops like sorghum are based on single crosses between two parents and bi-parental populations have only one opportunity for crossing over. However 34 break-up points are estimated to occur per crossing generation.Limited efforts have been made in generating multiple crosses (e.g., three-way or double crosses). In the present study eight parents viz., M35-1, Parbhani Moti, DSV5, CSV216R, CSV29R, CRS20, Sel.3 and CRS4 of rabi adaptation were used to synthesize four single crosses and two double crosses. Double and single crosses along with their parents were evaluated in Randomized Block Design in two replications and the mean values were used to estimate the magnitude of heterosis for yield and its attributing traits over mid-parent and better parent. Results revealed that there are significant differences for most of the traits and double cross hybrids were better in their performance over single cross hybrids. One of the double cross hybrid DC-2;((DSV5 × Sel.3) × (CSV216R × CRS4)) exhibited highest level of heterosis for the traits like panicle weight (Mp=64.27%;Bp=45.99%), grain yield per plant (Mp=81.72%; Bp=56.76%), fodder yield per plant (Mp=71.15%; Bp=55.82%) and 100 seed weight (Mp=63.27%; Bp=60%, with a highest mean value of 6.0g) whereas other double cross DC-1;((M35-1 × CSV-29R) × (Parbhani Moti × CRS-20))found superior for plant height, panicle exertion and panicle length. Even though two single cross hybrids viz.,CSV216R × CRS4 and Parbhani Moti × CRS20 showed good levels of heterosis for Panicle exertion, panicle length,grain yield and fodder yield but the values are less than double cross hybrids. So study indicated that an additional round hybridization involving more parents may be of much rewarding in diversifying the genetic base of breeding populations and realizing fair amount of heterosis in post rainy situation than that of bi-parental matingsICA

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Not AvailableForty two genotypes were tested together during rabi season 2015-16 under three water regimes 1. Well watered -irrigated throughout the crop season, 2. Water stressed ie irrigation till 45 days after sowing and 3. Water stressed ie. irrigation till 30 DAS along with four checks viz., M35-1, Phule Anuradha, CSV 22, and CSV 26. The design of experiment was split plot design with three replications. Drought tolerance and susceptible genotypes were categorised on the basis of stress susceptible index (SSI), Weighted Mean Index (WMI) and regression line. Based on these criteria genotypes Phule Anuradha x Sangola Hondi, Sangola hondi x BRJ 62, SLR 24 x BRJ 62, IC 392155, CRS 7, CRS 20, CRS 48, Selection 3 and IC - 343586 were categorised as drought tolerant. Correlations between peduncle length (cm) and days to flowering were negative and significant under all environments (-0.36* *,-0.44* * and -0.39* *) indicating higher peduncle length earlier the flowering. Under less soil moisture condition early flowering and maturity traits is important as it helps in completing life cycle with available soil moisture, thereby imparting drought tolerance. Correlations between grain yield and per cent panicle emergence were positive and significant (0.67* *, 0.44* * and 0.37* *) under all environments. Correlation between per cent reduction in grain yield and per cent reduction in leaf area at the time of flowering under one irrigation was (r=0.53*) significant and positive. Traits like early flowering, long peduncle length and less reduction in leaf area at the time of flowering were found to be associated with drought.Not Availabl

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