Influence of genetic variability on Zn response in recently improved corn (Zea mays L.) genotypes has not been investigated. Therefore, eight genotypes representing indigenous, hybrid, and composite varieties, were evaluated in the greenhouse using a Zn deficient loamy sand soil (Typic Torripsamments) at 0 (original soil), 5, and 10 ppm Zn applied to the soil. Zinc deficiency symptoms, dry matter yield response (6 weeks after sowing), Zn concentration, and P/Zn and Fe/Zn ratios were the criteria for evaluation. There was considerable variation among the eight genotypes in the severity of Zn deficiency symptoms, growth depression, Zn concentration, P/Zn, and Fe/Zn ratios under Zn stress conditions. The depression in shoot and root dry matter yield under Zn stress conditions ranged from 78 to 95 and 72 to 94%, respectively, as compared to 5 ppm supplemental Zn level. Zinc concentration in different genotypes under Zn stress condition varied from 7.4 to 20.5 ppm. The differential response among the genotypes was found to be associated with their capability to exploit soil Zn and/or translocate it to the shoot. The contribution of P/Zn and/or Fe/Zn balance in tissues to the variability in Zn responses was not significant.

Influence of genetic variability on Zn response in wheat (Triticum sp.) was evaluated in the greenhouse. There was considerable difference among 21 varieties in the time of appearance and intensity of deficiency symptoms, yield depression, and Zn concentration under Zn stress conditions. Without supplemental Zn, dry matter yields of shoot and roots were 8.6 to 33.5% and 9.4 to 36.8% lower, respectively, than at 5 ppm Zn level. Zinc concentration of varieties ranged from 4.2 to 28.3 ppm under zinc deficiency conditions. The differential response among the varieties was found closely linked to their efficiency in Zn utilization from the soil.

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The influence of genetic variability on the response of five cotton cultivars to Zn applied at 0 ppm (original Zn deficient soil), 5 ppm and 50 ppm was studied in a greenhouse experiment. Zinc content was determined in samples of shoots taken eight weeks after sowing and in samples of stock harvested at maturity. Typical zinc deficiency symptoms, varying in intensity among cultivars, were noted, which were characterized by interveinal chlorosis in the 3rd and 4th leaf and cupping.All the cultivars showed a response in yield to applied Zn both at 8 weeks after sowing and at maturity. At maturity, cultivars differed with respect to the magnitude of response of different plant parts to applied Zn. Some cultivars, recovered considerably from Zn stress conditions as plants matured. The lint yield of all the cultivars was highest with 50 ppm Zn. The yield of seed in 3 out of 5 cultivars was more with 50 ppm than with 5 ppm Zn. There was more difference among the cultivars in their shoot and stock yields than in the lint and seed yields. The effect of Zn deficiency was more pronounced on the lint and seed yields than on the stock yields.Zinc concentration in shoots at 8-weeks after sowing, and at maturity was not related to yield response.