Plant water status,H<Subscript>2</Subscript>O<Subscript>2</Subscript> scavenging enzymes,ethylene evolution and membrane integrity of <Emphasis Type="Italic">Cicer arietinum</Emphasis> roots as affected by salinity

The chickpea genotype, CSG-8962 was raised in screenhouse to study salinity induced changes in ethylene evolution, antioxidative defence system and membrane integrity in relation to changes in plant water and mineral content. At vegetative stage (60 d after sowing), the plants were exposed to single saline irrigation (0, 2.5, 5.0 and 10.0 dS m^–1). Sampling was done 3 d after saline treatments. The other sets of treated plants were re-irrigated with water and sampled after further 3 d. The _w of leaf and _s of leaf and roots decreased from –0.47 to –0.61 MPa, –0.67 to –1.23 MPa and from –0.57 to –0.95 MPa, respectively, with increasing salinity. Similarly, RWC of leaf and roots reduced from 87.5 to 72.3 % and 96.7 to 84.35 %, respectively. The decline in s of roots was mainly due to accumulation of proline and total soluble sugar. With salinity, increase in ethylene evolution, 1-aminocyclopropane-1-carboxylic acid (ACC) content and ACC oxidase activity was reported. Similarly, marked increase in H₂O₂ content (20 – 182 %) and lipid peroxidation (43 – 170 %) was observed. The defense mechanism activated in roots was confirmed by the increased activities of superoxide dismutase (SOD), peroxidase (POX), ascorbate peroxidase (APX), glutathione transferase (GTase), glutathione reductase (GR) and catalase (CAT) but ascorbic acid (AA) content was decreased. About 3-fold increase in Na⁺/K⁺ ratio and 2.5 fold increase in Cl^– content was observed. Upon desalinization, a partial recovery was observed in most of the parameters studied.     

The rock-phosphate solubilizing capacity ofPueraria javanica as affected by soil pH,superphosphate priming effect and symbiotic N2 fixation

Summary WhenPueraria javanica was grown on acid soil in a pot experiment, the legume’s acidifying effect, originating from an uptake pattern in which on an equivalence basis more nutritive cations than-anions were absorbed, was sufficient to mobilize rock phosphate even when added as very insoluble material. In neutral soil, a small quantity of triple superphosphate proved necessary to set into motion a chain of reactions in which the priming action of the TSP enables nodulation to take place followed, in order, by N₂ fixation, soil acidification and rock phosphate mobilization. More attention should be paid in tropical regions to mixed farming systems in which leguminous crops, like Pueraria, produce fodder for livestock whose faeces and urine, when properly collected, can be used for the manufacturing of biogas, after which the residues can serve as manure to food crops. Even when they prove unsuitable for beneficiation, many rock phosphates found in African and Latin American countries can be made useful as fertilizer for leguminous fodder crops.