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The zinc (Zn) requirement of a maize (Zea mays L.) hybrid ('FHY-396') and an indigenous variety ('EV-7004') was measured at low (22.4 ± 5°C) and high (28.8 ± 5°C) root-zone temperatures (RZT). Four Zn rates (0, 3, 9 and 27 mg kg-1 soil) were applied to a calcareous loam soil in pots for the glasshouse study. Shoot and root dry matter yields were significantly more at the higher RZT. Regardless the RZT, maximum relative shoot dry matter yield in hybrid and variety was produced, respectively, at 9 and 3 mg Zn kg-1 soil. Zinc concentration in roots and shoots of both the cultivars increased with Zn rates and it was significantly more at the higher RZT. Cultivars differed in critical Zn concentration (CZnC) required for maximum shoot dry matter yield. The CZnC ranged from 25 to 39 μg Zn g-1 plant tissue for optimum growth of both the cultivars at low and high RZT. [ABSTRACT FROM AUTHOR]

A pot study was conducted on Gujranwala series (Udic Haplustalf) to compare zinc (Zn) requirement of maize hybrids (FHY- 456, FHY- 396, and FHY- 421) and indigenous varieties (EV-1089, Golden, and Soneri). Uniform rates of nitrogen:phosphorus:potassium (N:P:K) and four rates of Zn were applied in triplicate according to CRD. There was a significant (P < 0.05) main and interactive effect of maize genotypes and zinc application on shoot growth and Zn uptake. The three maize varieties uniformly produced maximum shoot dry weight at 3 mg Zn kg-1 soil. The maize hybrids produced maximum shoot dry weight at 9 mg Zn applied kg-1 soil. A 6.3 mg Zn kg-1 plant tissue was optimum for FHY-421 (hybrid) and 9.5 mg Zn kg-1 plant tissue was optimum for Soneri (variety). Hence, more pronounced response in maize hybrids than indigenous varieties require higher rates of Zn application. However, further verification of the results is warranted under field conditions. [ABSTRACT FROM AUTHOR]