مطالعه پاسخ ژنوتيپ هاي پنبه به تغذيه برگي روي در خاك هاي آهكي

Cotton (Gossypium hirsutum L.) is one of the most important agricultural an‎d industrial crops of warm an‎d semi-arid regions, an‎d its production depends on genotype, plant nutritional status, an‎d soil chemical properties. In calcareous an‎d alkaline soils, high pH an‎d abundant calcium carbonate can reduce zinc availability, an‎d deficiency of this micronutrient may restrict photosynthetic processes as well as root an‎d shoot growth. This greenhouse pot experiment eva‎luated the physiological, growth, an‎d nutritional responses of seven cotton genotypes to foliar application of zinc sulfate in two calcareous soils differing in plant-available zinc. The experiment was conducted as a factorial based on a ran‎domized complete block design with three replications. Treatments consisted of seven genotypes, two foliar-zinc levels (unsprayed control an‎d zinc sulfate at 4 g L-1) an‎d two soil zinc conditions, giving 84 experimental units. Foliar spraying was carried out at the four- to six-leaf stage in two applications one week apart. The measured traits included photosynthetic pigments, chlorophyll fluorescence, net photosynthesis, stomatal conductance, transpiration, intercellular CO2 concentration, leaf number an‎d area, shoot an‎d root dry weight, total root length, root surface area, root volume, mean root diameter, an‎d Zn an‎d Fe concentrations in soil an‎d plant tissues. Data were analyzed using SAS 9.4 an‎d means were compared by the least significant difference test at the 5% probability level. Genotype, foliar zinc application, an‎d soil zinc status significantly affected most of the eva‎luated traits. Foliar zinc generally increased net photosynthetic rate, stomatal conductance to CO2, transpiration rate, concentration of photosynthetic pigments, Fv/Fm, Fm, leaf area, shoot an‎d root dry weight, an‎d root length, surface area an‎d volume, while reducing Fo an‎d Ci in many genotypes. The increase in shoot zinc concentration confirmed absorption an‎d translocation of foliar-applied zinc. Zinc limitation was more severe in the low-zinc soil, whereas foliar application partially compensated for reductions in physiological an‎d growth traits. Genotypic responses were not uniform, indicating meaningful genotypic variation in tolerance to zinc deficiency an‎d responsiveness to foliar zinc. Overall, foliar application of zinc sulfate at 4 g L-1 improved photosynthetic performance, root-system development, dry matter production, an‎d zinc nutritional status, particularly under low-zinc soil conditions; however, genotype selec‎tion should consider both zinc-deficiency tolerance an‎d the capacity to respond to foliar zinc.

پرويز احسان زاده

حسين شريعتمداري , حميدرضا عشقي زاده

حسن كريم مجني , اميرحسين خوش گفتارمنش