Response of four wheat genotypes to Zn foliar application on a calcareous soil

Zinc deficiency is one of the important reasons that cause to decrease wheat yield in the entire world especially in calcareous soil of Iran. An experiment with a randomized complete block design, and four replications in a factorial arrangement was conducted to investigate differential response of some wheat genotypes to foliar application of Zn. Four wheat genotypes (Pastur cultivar, line M-75-7, line S-75-20 and Chamran cultivar) and four foliar application levels of Zn (0, 5, 10 and 15 kg Zn ha-1 from the source of ZnSO4) were used. Results showed that the studied wheat genotypes significantly varied in yield components, the line S-75-20 had the highest yield components (number of spike per m2, number of fertilized spiklets in spike and number of seeds in spike) as well as grain yield (3151 kg ha-1) among wheat genotypes. The effect of foliar application of Zn on grain yield was depended on the rate of applied Zn and wheat genotype. Foliar spray of 5 and 15 kg Zn ha-1 increased the grain yield as compared to the control while a decrease in grain yield was found by application of 10 kg Zn ha-1. Among different treatments, the highest grain yield (3914 kg ha-1) was related to the line S-75-20 in 15 kg Zn ha-1 treatment. Wheat genotypes were significantly different in Zn uptake. The highest and lowest Zn uptake was related to the line S-75-20 and Chamran, respectively. Line S-75-20 had the lowest Zn foliar application efficiency, as calculated based on the grain and straw yield, among the studied genotypes. It seems that foliar application of Zn in calcareous soils with similar condition to the present experiment could not guarantee correcting plant Zn deficiency. Differential response of wheat genotypes to foliar spray of Zn is an important factor that has to be considered in Zn fertilizer management.