Iron deficiency chlorosis (IDC) causes a significant reduction in yield of groundnut grown in calcareous and alkaline soils in India. The main aim of the study was to assess genotypic differences for morpho-physiological parameters associated with IDC resistance across different stages and their effect on yield and its related traits. The factorial pot experiment was comprised of two major factors, i) soil-Fe status [normal-Fe, deficit-Fe], and ii) genotypes [five] with differential IDC response, constituting 10 treatments. They were assessed for five morpho-physiological parameters associated with IDC resistance across five crop growth stages and also yield and its related traits. Associations between these traits were also estimated. Under deficit-Fe conditions, IDC resistant genotypes recorded significantly lower visual chlorosis rating (VCR), higher SPAD values, active Fe, chlorophyll content, peroxidase activity, and high yield compared to susceptible ones. Between normal-to deficit-Fe soils, resistant compared to susceptible genotypes showed no change in VCR scores; a lower reduction in SPAD, chlorophyll, active Fe, peroxidase activity, and pod yield. Under deficit-Fe conditions, high yield among resistant genotypes could be attributed to higher seed weight, number of pods and haulm yield, while contrasting reduction in main stem height and number of primaries. The results indicate that for initial large-scale screening of groundnut genotypes for IDC resistance, SPAD values are most ideal while active Fe could be utilized for confirmation of identified lines.

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.

No abstract

Iron deficiency is an important abiotic constraint reducing the growth and yield of groundnut especially under calcareous soils. Foliar application of Fe-chelates can overcome iron deficiency but it is not economical. Evaluation of 318 recombinant inbred lines (RILs) along with parents for iron deficiency chlorosis (IDC) and productivity traits under iron deficient soils over three years indicated significant genotypic and genotypic x environment interaction (GE) component for both IDC and productivity traits. Among the RILs, range of variation was higher than that of the parents for visual chlorotic rating (VCR), SPAD chlorophyll meter reading (SCMR) and productivity parameters across three years indicated the presence of transgressive segregants. VCR had higher phenotypic and genotypic, variances, heritability and genetic advance as per cent of mean (GAM) in all the three years as compared to SCMR. Among productivity traits, pod yield (g plant-1) had higher PCV and GCV compared to shelling per cent and 100 seed weight. Significant negative correlation between VCR and pod yield per plant indicated effect of IDC on productivity in RILs. Nine lines were superior for both IDC tolerance and productivity traits. This extensive phenotyping of RIL population for IDC tolerance under iron deficient conditions can be used for identification of genomic regions associated with IDC tolerance by genotyping of this RIL population.

No abstract