No abstract

In a field study, the effect of iron source through foliar as well as basal application was studied on lime induced iron-deficiency chlorosis (LIIC), chlorophyll content, nitrate reductase activity, available Fe and micronutrients in groundnut.The visual chlorotic rating screen of various Fe-efficient and Fe-inefficient cultivars clearly identified Fe-efficient and Fe-inefficient. Tirupati-4 was showing symptoms of chlorosis and was Fe-inefficient. Fe absorption capacity varied among cultivars. Applications of iron increased active Fe content in LGN-2 by 5.6 % and 163.18% in CSMG-84-1 respectively. A significant increase in chlorophyll content (10%) and nitrate reductase (110%) was observed with foliar spray of FeSO 4 . A significant damage of lipid peroxidation was observed in absence of iron which was improved by 37% in Tirupati-4 and 16.67% in CSMG-84-1 by foliar and basal supplementation of Fe, respectively. A strong correlation among the Fe, Mn, Zn and K depicted ionomic interaction with different treatments. Based on the ion absorption capacity and the level of chlorosis, the groundnut genotypes were grouped as tolerant, moderately tolerant and sensitive to iron chlorosis.

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 T 1 , 25 % less than ET in T 2 and 48 % less than ET in T 3 against the cumulative evaporative demand of 412 mm. The relative water content (RWC) of peanut leaves reduced by cutting irrigation from 93.5 % in T 1 to 91.1 % in T 2 and 77.2 % in T 3 but, net photosynthetic rate (P N ) was higher in T 2 (29.6 μmol m -2 s ) which was statistically at par with GG 20, ICGV 86590, TAG 24, SB XI, TMV 2 and TPG 41. The nonphotochemical quenching (NPQ) varied with different irrigation treatment with lowest in T 2 and highest in T 3 . The deepoxidation state (DeS) was 38 % in T 1 and T 2 but, increased to 47 % in T 3 due to the sever water deficit stress. Applying 20 % higher irrigation than the ET demand (T 1 ) 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 (T 2 ) 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.

-From a fi eld experiment, the changes in oxidative stress and antioxidant enzyme activities were studied in six Spanish peanut cultivars subjected to 25−30 days of water defi cit stress at two different stages: pegging and pod development stages. Imposition of water defi cit stress signifi cantly reduced relative water content, membrane stability and total carotenoid content in all the cultivars, whereas total chlorophyll content increased at pegging stage but decreased at pod developmental stage. Chlorophyll a/b ratio increased under water defi cit stress in most of the cultivars suggesting a greater damage to chlorophyll b rather than an increase in chlorophyll a content. Oxidative stress measured in terms of H 2 O 2 , superoxide radical content and lipid peroxidation increased under water defi cit stress, especially in susceptible cultivars such as DRG 1, AK 159 and ICGV 86031. Relationship among different physiological parameters showed that the level of oxidative stress, in terms of production of reactive oxygen species, was negatively correlated with activities of different antioxidant enzymes such as superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glutathione reductase. In conclusion, the study shows that water defi cit stress at pod development stage proved to be more detrimental than at pegging stage. The higher activities of antioxidant enzymes in the tolerant cultivars like ICGS 44 and TAG 24 were responsible for protection of oxidative damage and thus provide better tolerance to water defi cit stress.