Dinoseb and Triacontanol as Growth Regulators in Irrigated and Nonirrigated Field Corn

The growth regulators dinoseb (2-sec-butyl-4,6-dinitrophenol) and triacontanol [CH₃(CH₂)₂₈CH₂OH] have previously been applied to several crops, including corn (Zea mays L.), in efforts to stimulate yields. Field performance has been erratic with both yield increases and yield decreases reported. It was hypothesized that crop response to dinoseb and triacontanol may be influenced by environmental stress on the growing crop to which they are applied. This is a report of two field experiments (1978 and 1979) in which dinoseb and triacontanol were applied to irrigated and water-deficient field corn to test this hypothesis. Two corn hybrids (Pioneer 3369A and Funks G4646) were planted in irrigated and nonirrigated split blocks. Dinoseb (17.4 g/ha) and triacontanol (4.0 g/ha) were applied as foliar sprays, 2 weeks before tasseling. Corn grain yields were significantly reduced in 11 of 12 dinoseb-treated vs. untreated comparisons. Yield reductions averaged 18.0% in irrigated corn and 18.4% in nonirrigated corn. A significant irrigation ✕ dinoseb interaction occurred in only one of six comparisons. Some of the grain yield reduction in dinoseb-treated plots could be attributed to reduced harvest index and reduced percentage ear fill. Triacontanol did not affect grain yield in six of eight comparisons of triacontanol-treated vs. untreated plots. One of the four irrigation ✕ triacontanol interactions was significant, showing a yield increase due to triacontanol under irrigation, and a yield decrease in waterdeficient corn. Harvest index and percentage ear fill were not affected by triacontanol. The hypothesized interaction of environmental stress with the growth regulators dinoseb and triacontanol was not substantiated in these experiments. Triacontanol had minimal effect on corn performance, and dinoseb had very detrimental effects on both irrigated and water-deficient corn. It is suggested that the inconsistent performance of these compounds, as reported in the literature, should not be attributed to environmental conditions of the growing crops.