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Fluid Journal : Fluid Journal 1999-2001
3 Fluid Journal Winter 1999 severe leaf shredding from hail seven days before tasseling in late July, which decreased yield potential. Yield response varies 1993. There were significant yield differences between hybrids at each of the three sites (Figures 1, 2, and 3). Corn yields were significantly different with Fe treatments at Site 1 (pH 8.6) and Site 2 (pH 8.2). The foliar sprays of FeSO4•7H2O at the 8.6 pH site (Figure 1) were effective on the tolerant but not on the non-tolerant hybrid, producing more growth and greening on the tolerant than on the non-tolerant hybrid. It is an inexpensive treatment, but may be effective only if a tolerant hybrid is planted. The seed row-applied FeSO4•7H2O produced more growth and chlorosis correction than the foliar treatment. 1994. Due to hail, Site 2 and Site 3 showed no significant treatment effects, but Site 1 did (Figure 1). 1995. Grain yields showed similar increases (Figure 1). The 100-lb/A rate of FeSO4•7H2O was sufficient to correct chlorosis on the tolerant hybrid, but the 150-lb/A rate was required for the non- tolerant hybrid. There were no marked differences in final plant population with the highest rate of FeSO4•7H2O (data not shown). Chlorophyll readings Chlorophyll meter readings were significantly increased by Fe treatment onSite1,butnotonSite2andSite3. The range of chlorophyll meter readings is significantly wider than those reported for nitrogen (N) deficiency. Therefore, the readings defined chlorosis sufficiently to map chlorosis severity in whole fields that could be used as a basis for selecting different corn hybrids and Fe treatments. Chlorophyll meters are expensive (U.S. $1,200). However, measuring plant height may provide sufficient information to produce maps of severely chlorotic sites. Correlation of plant height and chlorophyll meter readings with final grain yield of the tolerant Pioneer brand 3362 were both significant. Response was similar for the Pioneer brand 3398. The relationship between grain yield and mid-season chlorophyll meter readings, as influenced by Fe treatments, shows the potential for determining chlorosis severity and projected yields (Figure 4). Dr. Hergert is professor; Dr. Nordquist is professor; Peterson is research technologist, and Skates is facility manager in the Cooperative Extension at the University of Nebraska. Figure 3. Effect of Fe source on grain yields of corn at Site 3, pH 7.7, Hergert, et al. , University of Nebraska, 1993-1994. Figure 4. Effect of Fe treatment on grain yield and chlorophyll meter readings on two hybrids, Site 1, Hergert, et al., University of Nebraska, 1993. 80 TNTTNTT T T T NT NT NT NT 1993 1994 100 120 140 160 180 200 Check Foliar Fe NT = Non-tolerant Hybrid Fe SO4 T= Tolerant Hybrid Yield-bu/A 200 200 Yield-bu/A Yield-bu/A Meter Meter Yield Yield Chlorophyll Chlorophyll Reading Reading 150 150 100 100 50 50 10 10 20 20 30 30 40 40 50 50 60 60 CK CK Foliar Foliar Pioneer Brand 3362 Pioneer Brand 3398 FeSO4 FeSO4
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