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TEMPERATURE DEPENDENT PHENOLOGICAL MODELS FOR DENT CORN AND POPCORN (ZEA MAYS L.) (GROWTH STAGING)
Abstract
Phenological models are used widely to predict development of dent corn (Zea mays L.). Genotype by photoperiod and genotype by temperature interactions for maturity have been recorded for identical hybrids grown across a range of latitudes and planting dates restricting inferences from maturity predictions derived using generalized corn phenology models. Limited data exist for popcorn. Research objectives included evaluating dent corn phenological keys on popcorn, developing improved thermal phenology models, and comparing reference points and procedures for calculating thermal units. Automated climate stations in Nebraska facilitated modeling corn phenology using hourly averages. Data was collected in eastern Nebraska during 1982-84: incorporating daily and hourly climate data, planting date effects, one locally adapted dent corn hybrid (B73 x Mo17), and three differently maturing popcorn hybrids (P410, P609, and "Iopop12"). Corn growth was described at 150 growing-degree-day intervals (base 10(DEGREES)C) using both current and modified staging procedures. Existing corn phenology descriptions were unsuitable for modeling morphologically and genetically diverse materials with contrasting leaf development, leaf number, grain type, and grain development. A modified phenological key and numeric analogue were developed. Violations of standard regression assumptions were associated with incorrect model specification, heterogeneity of error variance, and non-independence of errors. Superior models were developed by using modified staging procedures, partitioning data into emergence then pre- and post-anthesis development, incorporating planting data effects (pre-plant heat sums) as a covariate, using hourly heat sums, and using growth curve analysis. Response profiles for emergence, pre-, and post-anthesis phenology differed significantly (0.01 level) between years (1982-83), among planting dates within years, among hybrids, and among hybrids within planting dates. Hourly heat sums (base 5(DEGREES)C) varied less between years when compared with other procedures. Pre-plant heat sums accounted for a significant amount of variation (0.01 level) and were used to develop tables containing regression coefficients for describing early-, mid-, and late-planted corn phenology. Maturity ratings for some corn hybrids changed as planting date was delayed; Iopop 12 matured earlier, P410 remained unchanged, P609 matured later, and B73 x Mo17 matured earlier then later.
Subject Area
Agronomy
Recommended Citation
STEVENS, E. JOHN, "TEMPERATURE DEPENDENT PHENOLOGICAL MODELS FOR DENT CORN AND POPCORN (ZEA MAYS L.) (GROWTH STAGING)" (1985). ETD collection for University of Nebraska-Lincoln. AAI8521479.
https://digitalcommons.unl.edu/dissertations/AAI8521479