Stalk lodging in popcorn and related plant characteristics as influenced by two hybrids and treatment with ethephon
Abstract
Stalk lodging of popcorn (Zea mays everta L.) causes considerable economic losses. Use of ethephon (2-chloroethyl phosphonic acid) as an antilodging agent in small grains is well documented. Use of ethephon could result in reduced stalk lodging in popcorn. Two popcorn hybrids, P608 and P410, which differed in stalk strength were studied in field experiments on a Chalmers silty clay loam soil (fine silty, mixed, mesic Typic Haplaquoll) and on a Raub silt loam soil (fine silty, mixed, mesic Aquic Argiudoll) during 1985 and 1986 to determine the nature of genetic lodging resistance. The effects of ethephon treatment on lodging were determined and the mechanism for the lodging response due to ethephon treatment was compared to genetic lodging resistance. Ethephon was applied at 0 and 0.42 kg active ingredient (a.i.) ha$\sp{-1}$ when the initiating tassel was between 0.32 and 0.64 cm long. The two popcorn hybrids differed in genetic stalk lodging resistance due to differences in ear height and resistance to crushing. Resistance to crushing was related to differences in specific gravity, concentrations of nonstructural carbohydrates, and concentration of lignin in the 2nd internode above the soil surface. Treatment with ethephon reduced lodging and therefore increased harvestable yield, but did not affect grain yield or popping quality. Plant height, ear height, and the ratio of ear-to-plant height were reduced by ethephon treatment and were responsible for the reduction in stalk lodging. Ethephon treatment reduced resistance to crushing and specific gravity and thus decreased stalk strength. Internode segment weight and rind thickness increased due to ethephon treatment, but were not related to the ethephon-induced reduction in resistance to crushing. Ethephon treatment decreased concentrations of neutral detergent fiber (NDF), lignin, and cellulose and increased the concentration of hemicellulose. These ethephon-induced changes in the concentration of nonstructural carbohydrates and lignin altered the cell wall superstructure which partially explains the ethephon-induced reduction in resistance to crushing. Because treatment with ethephon increased lodging in several hybrids in a study conducted in 1985, additional studies on the effects of ethephon treatment on a wider spectrum of popcorn hybrids are recommended.
Degree
Ph.D.
Advisors
Vorst, Purdue University.
Subject Area
Agronomy
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