Accumulation of resveratrol, ferulic acid and iron in seeds confer iron deficiency chlorosis tolerance to a novel genetic stock of peanut (Arachis hypogaea L.) grown in calcareous soils.

Peanut is mostly grown in calcareous soils with high pH which are deficient in available iron (Fe2+) for plant uptake causing iron deficiency chlorosis (IDC). The most pertinent solution is to identify efficient genotypes showing tolerance to limited Fe availability in the soil. A field screening of 40 advanced breeding lines of peanut using NRCG 7472 and ICGV 86031 as IDC susceptible and tolerant checks, respectively, was envisaged for four years. PBS 22040 and 29,192 exhibited maximum tolerance while PBS 12215 and 12,185 were most susceptible. PBS 22040 accumulated maximum seed resveratrol (5.8 ± 0.08 ppm), ferulic acid (378.6 ± 0.31 ppm) and Fe (45.59 ± 0.41 ppm) content. Enhanced chlorophyll retention (8.72-9.50 µg ml-1), carotenoid accumulation (1.96-2.08 µg ml-1), and antioxidant enzyme activity (APX: 35.9-103.9%; POX: 51- 145%) reduced the MDA accumulation (5.61-9.11 µM cm-1) in tolerant lines. The overexpression of Fe transporters IRT1, ZIP5, YSL3 was recorded to the tune of 2.3-9.54; 1.45-3.7; 2.20-2.32- folds respectively in PBS 22040 and 29,192, over NRCG 7472. PBS 22040 recorded the maximum pod yield (282 ± 4.6 g/row), hundred kernel weight (55 ± 0.7 g) and number of pods per three plants (54 ± 1.7). The study thus reports new insights into the roles of resveratrol, ferulic acid and differential antioxidant enzyme activities in imparting IDC tolerance. PBS 22040, being the best performing line, can be the potent source of IDC tolerance for introgression in high yielding but susceptible genotypes under similar edaphic conditions. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-023-01321-9.

Photosynthetic characteristics of peanut genotypes under excess and deficit irrigation during summer.

In a field experiment three irrigation treatments were given to twelve peanut genotypes through drip. At 80 days after sowing (DAS) the amount of irrigation applied was 20 % higher than the evaporative demand (ET) in T1, 25 % less than ET in T2 and 48 % less than ET in T3 against the cumulative evaporative demand of 412 mm. The relative water content (RWC) of peanut leaves reduced by cutting irrigation from 93.5 % in T1 to 91.1 % in T2 and 77.2 % in T3 but, net photosynthetic rate (P N) was higher in T2 (29.6 µmol m(-2) s(-1)) than T1 (28.6 µmol m(-2) s(-1)) and T3 (24.3 µmol m(-2) s(-1)) at 75-80 DAS. Peanut genotype ICGV 91114 showed the highest P N (30.9 µmol m(-2) s(-1)) which was statistically at par with GG 20, ICGV 86590, TAG 24, SB XI, TMV 2 and TPG 41. The non-photochemical quenching (NPQ) varied with different irrigation treatment with lowest in T2 and highest in T3. The de-epoxidation state (DeS) was 38 % in T1 and T2 but, increased to 47 % in T3 due to the sever water deficit stress. Applying 20 % higher irrigation than the ET demand (T1) does not warrant any extra benefits in terms of higher photosynthesis in peanut at 75-80 DAS. Further, a reduction of 25 % of the ET (T2) in peanut seems to be the ideal condition for photosynthesis and desirable chlorophyll fluorescence parameters at 80 DAS. Girnar 3 and ICGV 91114 showed NPQ value above 2.2 and higher de-epoxidation state, maintained least deviation in Fv/Fm and Fv'/Fm' under severe water deficit condition are promising peanut genotypes.

Physiological efficiencies in 186 peanut cultivars of various botanical groups

Peanut is a major oilseeds crop of India with its largest area in the world, but its productivity is less than the world average. Though India has released a number of peanut cultivars, studies on the physiological efficiencies of such varieties are scarce. In this study, we tried to elucidate the physiological basis, net photosynthesis (PN), transpiration (E), stomatal conductance (gs), chlorophyll fluorescence (Fv/Fm), SPAD chlorophyll meter reading (SCMR), chlorophyll (chl) contents in leaf at 60-65 days of crop and pod and haulm yields at harvest in 186 peanut cultivars during Kharif season. The average and range of PN were 19.8 and 11.4-31.4 µ mol m-2s-1, gs 0.25 and 0.11-0.45 m s-1, E 6.84 and 3.96-11.61 m mol m-2s-1, SCMR 34.0 and 20.3-44.1, total chl 7.79 and 3.07-15 mg g-1 leaves, Fv/Fm 0.846 and 0.802-0.887, pod yield 179 and 68-309 g m-2 and haulm yield 464 and 144-884 g m-2 and a number of superior cultivars identified. The pod yield was strongly correlated with SCMR, chl and carotenoid contents, haulm yield and pods plant-1, but weakly associated with PN, gs, and Fv/Fm. The PN correlated with gs and E, however, SCMR was the single best parameter. The Spanish and Virginia bunch groups showed most desirable physiological traits. The cultivars TPG 41, Chintamani, M 37, GG 8, GG 13, Kadiri 7 and M 522 showed superior physiological traits for their cultivation.