Doubled haploid (DH) technology has changed the maize-breeding landscape in recent years. Traditionally, DH production requires the use of chemical doubling agents to induce haploid genome doubling and, subsequently, male fertility. These chemicals can be harmful to humans and the plants themselves, and typically result in a doubling rate of 10%–30%. Spontaneous genome doubling and male fertility of maize haploids, without using chemical doubling agents, have been observed to a limited extent, for nearly 70 years. Rates of spontaneous haploid genome doubling (SHGD) have ranged from less than 5% to greater than 50%. Recently, there has been increased interest to forgo chemical treatment and instead utilize this natural method of doubling. Genetic-mapping studies comprising worldwide germplasm have been conducted. Of particular interest has been the detection of large-effect quantitative trait loci (QTL) affecting SHGD. Having a single large-effect QTL with an additive nature provides flexibility for the method of introgression, such as marker-assisted backcrossing, marker-assisted gene pyramiding, and systematic design. Moreover, it allows implementation of new methodologies, such as haploid-inducer mediated genome editing (HI-edit) and promotion of alleles by genome editing. We believe the use of SHGD can further enhance the impact of DH technology in maize.

Eastern gamagrass is a warm‐season perennial grass that has excellent forage nutritional quality and a broad range of adaptations. Despite the favorable forage qualities, agronomic issues persist; most important for grazing systems is stand persistence from preferential grazing when growing in mixed species communities. Stand persistence when monoculture stands are grazed has been previously studied, and it has been observed that stands decline under high stocking rates or low grazing height. The objective of our study was to evaluate if an improvement of stand persistence under defoliation to a low‐cut height is feasible through the breeding of improved lines. A persistence trial was conducted using a completely random design and eight replications to evaluate the stand persistence of two commercial cultivars, two experimental lines, and an ecotype selection. Defoliation occurred by grazing and mowing to a height of 8 cm three‐to‐four times over the course of five growing seasons. Stand counts of live plants were taken following the final defoliation of the season. Mixed linear regression modeling indicates significant differences between genotypes developed in years where no grazing occurred. An ecotype selection from Northwest Oklahoma exhibited significantly greater persistence than the cultivar Pete and the other experimental lines. These results suggest that different alleles exist for critical persistence genes, indicating it may be feasible to improve the trait through breeding and selection.

Fertilization and kernel development are crucial for breeding and agronomic production of maize (Zea mays L.), which is prone to outcrossing. Because of this tendency, a major issue for organic corn farmers is to maintain genetic purity of their crop. One way to maintain this purity is to use a unilateral cross incompatibility system such as Ga1‐s. However, lack of complete pollen exclusion has been reported in Ga1‐s heterozygotes, complicating introgression of this trait into breeding germplasm. A systematic, quantitative evaluation of pollen exclusion rates in breeding lines would greatly facilitate use of this system. The purpose of this study is to quantitatively evaluate exogenous ga1 pollen exclusion of a diverse set of Ga1‐s/ga1 F₁ hybrids representing the stiff stalk and nonstiff stalk heterotic groups, and the Iowa Synthetic Corn Borer population. Differences between genotypes but not heterotic groups were observed when applying exogenous ga1 pollen onto heterozygotes possessing the same Ga1‐s allele, indicating there are epistatic interactions between Ga1‐s and modifier loci in the ga1 parents tested.

Sorghum is an important forage crop in many cropping systems. Nitrate can accumulate in the vegetative plant tissue to levels high enough that result in fatality when fed to ruminant livestock when grown under high nitrate conditions. If variation among inbred lines can be documented for nitrate concentration, it may be possible to reduce nitrate accumulation within forage sorghum hybrids by selecting inbred lines having lower nitrate accumulation. The goal of this study was to evaluate a diverse set of male‐sterile sorghum inbred lines grown under high nitrate conditions, to observe if genotypic variation exists among lines used to produce forage sorghum hybrids. Forty replicates of 20 sorghum A‐lines were grown in a greenhouse and received either 272 kg ha⁻¹ or 408 kg ha⁻¹ of actual nitrogen per plant through applications of ammonium nitrate. Variance components were extracted from linear regression models and reliability was estimated on an entry‐mean basis. Leaf and stem reliability estimates were 0.95 and 0.93, respectively. These reliability estimates indicate the genetic variance comprised most of the phenotypic variance, and that our measurements were consistent. Significant differences were also observed between genotypes for both leaf and stem tissue. Therefore, sufficient genetic variance exists for developing male sterile sorghum inbred lines having leaf nitrate concentrations below the potentially lethal toxicity threshold of 10,000 μg g⁻¹.