Screening cotton cultivars for efficient utilization of zinc in chelator-buffered nutrient solution
2001
Irshad, M.
A solution culture experiment was conducted in wire house of the Department of Soil Science, University of Agriculture, Faisalabad, with the objectives of: To study differential growth response among cotton cultivars grown with adequate and deficient Zn level and to evaluate, the suitability of DTPA to induce Zn-deficiency for initial screening of cotton cultivars. The seeds were germinated in polyethylene lined iron trays containing pre- washed sand. One week old uniform seedlings were mounted in floating thermopol sheets, in two iron tubs (200 L capacity each) containing half strength Johnson's modified solution as a basal growth medium with deficient and adequate levels of Zn. For deficient level Zn deficiency was induced by adding 50 muM excess DTPA of all micronutrient (ZN + Cu + Fe + Mn) concentrations. Experimental layout was completely randomized factorial with six repeats of each cultivar in both the treatments. After one month the plants were harvested, separated into roots, and shoots and weighted after oven drying. The fine ground samples of shoot were digested to estimate their Zn, Cu, Fe and Mn concentrations and data was subjected to statistical analysis. The results obtained are summarized in the following pages. Cotton cultivars differed significantly in SDM, RDM, TDM, ZnSF and Zn utilization efficiency due to differential Zn supply in tile growth medium. FH-900 and VH-137 proved efficient in Zn utilization and biomass accumulation under adequate as well as deficient Zn supply. Zn concentration in cotton shoots of plants grown in chelator- buffered solution (Zn deficient) was 8-fold lower compared to those grown with adequate Zn. Further more, Zn concentration in Zn deficient solution plants was lower than the critical concentration of Zn (less than 20 mg kg-1) reported in literature for diagnosis the deficiency in cotton plant. Typical Zn deficiency symptoms i.e. inward curling of top leave, were evident in the plants grown in DTPA-buffered Solution. This indicates that the DTPA can he successfully used to induce Zn deficiency for initial screening of cotton cultivars against Zn deficiency. Fe, Cu and Mn concentrations were also reduced in shoot of cotton cultivars grown with chelator- buffered solution. However, the decrease concentration was not enough to warrant deficiency of these elements.
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