Methods for identifying frost injury in immature maize seed

Fall frost damage is a major threat to maize (Zea mays L.) seed production in the central United States. Frost events prior to harvest can cause various physical, mechanical, biochemical, and physiological changes to immature seed corn. These changes can lead to decreased germination and vigor. Early detection of frost damage could reduce the financial loss caused by poor emergence when these seed lots are planted. The central hypotheses of this dissertation are that the severity of a frost event can be quantified shortly after seed has been harvested and dried, and that the magnitude of the damage is associated with seed development and genetic background of the seed. This information can be used to predict field emergence of frosted seed lots. Many different aspects of frost damage have been explored in this project, which provides several methods for identifying frost damage in maize seed. This project advances our understanding of seed physiology as related to frost damage and changes in physiology during seed maturation. Chapter 2 is a practical application of the tetrazolium test for identifying frost damage in seed corn and relating these results to vigor. Chapter 3 discusses the influence of female parent and moisture content at harvest in frost tolerance or injury. Chapter 3 also provides a detailed analysis of seed quality tests and their usefulness in predicting field emergence of frost damaged seed. Chapter 4 establishes the use of RNA extraction and qRT-PCR as a valid method for evaluating gene expression in dry maize seed

Seed Quality Assurance in Maize Breeding Programs: Tests to Explain Variations in Maize Inbreds and Populations

Maize (Zea mays L.) breeders are interested in evaluating the seed quality of their inbred lines, as seed quality has a strong relationship to field emergence. There is little information, however, on the influence of the seed quality of the inbred on field emergence of the hybrid. The objectives of this research were to (i) determine whether seed quality tests and a seed quality index of the inbred parents and F2 seed are correlated with field emergence of F1hybrids, and (ii) determine how many tests are necessary to calculate this index. Standard germination (SG), saturated cold (SC), and soak (Soak) tests, and the inbred quality index (IQI) were calculated on inbred parents and their corresponding F2 progeny, and field emergence was measured on associated F1 hybrids produced in Clinton, IL in 2002 and 2003. The tests and index of the parental inbreds and F2 progeny correlated poorly with early field emergence of the F1 hybrids. All tests were required to calculate the seed quality index. By averaging several seed quality tests into a single index, the poor seed quality performance of inbreds and F2 populations in some tests can be masked by other tests. The seed quality index might be useful when ranking inbreds based on seed quality but not as a selection tool

Methods for identifying frost injury in immature maize seed

Fall frost damage is a major threat to maize (Zea mays L.) seed production in the central United States. Frost events prior to harvest can cause various physical, mechanical, biochemical, and physiological changes to immature seed corn. These changes can lead to decreased germination and vigor. Early detection of frost damage could reduce the financial loss caused by poor emergence when these seed lots are planted. The central hypotheses of this dissertation are that the severity of a frost event can be quantified shortly after seed has been harvested and dried, and that the magnitude of the damage is associated with seed development and genetic background of the seed. This information can be used to predict field emergence of frosted seed lots. Many different aspects of frost damage have been explored in this project, which provides several methods for identifying frost damage in maize seed. This project advances our understanding of seed physiology as related to frost damage and changes in physiology during seed maturation. Chapter 2 is a practical application of the tetrazolium test for identifying frost damage in seed corn and relating these results to vigor. Chapter 3 discusses the influence of female parent and moisture content at harvest in frost tolerance or injury. Chapter 3 also provides a detailed analysis of seed quality tests and their usefulness in predicting field emergence of frost damaged seed. Chapter 4 establishes the use of RNA extraction and qRT-PCR as a valid method for evaluating gene expression in dry maize seed.</p

Determining the Extent of Frost Damage in Maize Seed Using the Tetrazolium Test

Frost damage in seed corn causes a significant decrease in seed quality. The tetrazolium (TZ) test has been used to identify types of physiological damage in several plant species, including frost damage in corn. Quantifying the amount of seed damaged by frost and the consequent loss of seed vigor are important for making management decisions. The current tetrazolium test procedures provide seed viability information but do not estimate seed vigor. In our project, the tetrazolium staining procedure was modified to allow separation of viable seeds into vigor categories. Vigor categories were defined based on Association of Official Seed Analysts (AOSA) recommendations, previous research, and current observations. The results from the tetrazolium test were compared with standard germination and saturated cold tests during the first 6 months of storage. The staining procedure aided in visual identification of frost damage. Although a strong correlation was found between seed viability as determined by the tetrazolium test, the standard germination test, and the saturated cold test, sorting seeds into vigor categories in the tetrazolium test did not improve the correlation between the tetrazolium test and the saturated cold test.This is a manuscript of an article published as DeVries, Mindy, and A. Susana Goggi. "Determining the extent of frost damage in maize seed using the tetrazolium test." Crop Management 5, no. 1 (2006). doi: 10.1094/CM-2006-0414-01-RS. Posted wtih permission.</p

Seed Quality Assurance in Maize Breeding Programs: Tests to Explain Variations in Maize Inbreds and Populations

Maize (Zea mays L.) breeders are interested in evaluating the seed quality of their inbred lines, as seed quality has a strong relationship to field emergence. There is little information, however, on the influence of the seed quality of the inbred on field emergence of the hybrid. The objectives of this research were to (i) determine whether seed quality tests and a seed quality index of the inbred parents and F2 seed are correlated with field emergence of F1hybrids, and (ii) determine how many tests are necessary to calculate this index. Standard germination (SG), saturated cold (SC), and soak (Soak) tests, and the inbred quality index (IQI) were calculated on inbred parents and their corresponding F2 progeny, and field emergence was measured on associated F1 hybrids produced in Clinton, IL in 2002 and 2003. The tests and index of the parental inbreds and F2 progeny correlated poorly with early field emergence of the F1 hybrids. All tests were required to calculate the seed quality index. By averaging several seed quality tests into a single index, the poor seed quality performance of inbreds and F2 populations in some tests can be masked by other tests. The seed quality index might be useful when ranking inbreds based on seed quality but not as a selection tool.This article is published as Goggi, A. Susana, Petrutza Caragea, Linda Pollak, Gina McAndrews, Mindy DeVries, and Kevin Montgomery. "Seed quality assurance in maize breeding programs: Tests to explain variations in maize inbreds and populations." Agronomy journal 100, no. 2 (2008): 337-343. doi: 10.2134/agronj2007.0151.</p