Doubled haploid (DH) technology is widely used in maize breeding because of its ability to produce 100% homozygous inbred lines within a short period of time. This efficiency has made DH technology an attractive tool for maize breeders, allowing its incorporation into breeding programs. This technology also facilitates advanced breeding techniques such as genome editing and the conversion of elite inbred lines into their cytoplasmic male sterility counterparts. The successful integration of DH technology into various maize breeding programs worldwide has spurred extensive research on the genetic basis and mechanisms underlying haploid induction, leading to the identification of key quantitative trait loci (QTL) aimed at improving efficiency and reducing costs. Additionally, new phenotypic markers are being explored for use along with the R1-nj marker to enhance the accuracy of haploid seed and plant identification. Efforts are underway to identify alternatives to colchicine, a toxic and carcinogenic compound commonly used for chromosome doubling. Nondestructive methods, such as nuclear magnetic resonance, Fourier transform Raman spectroscopy, and flow cytometry, are being developed to enable fast and accurate haploid identification and automate the process for large-scale breeding programs. As these advancements improve DH technology, the maize hybrid breeding paradigm is undergoing a substantial transformation. However, several challenges remain unaddressed.

This study was carried out to select waxy corn inbreds with good general combining ability through a diallel analysis of 10 half diallel crosses among five inbreds developed from Korean maize landraces. Total of 21 agronomic and palatability traits were investigated over two locations in 2016. There was a significant hybrid by location interaction found in plant height, ear height, number of tillers/plant, per ear weight, ear tip filling, ear commercial value and sweetness when four additional check cultivars were included in the analyses. A significant general combining ability by location interaction was found in ear height, number of tillers/plant, per ear weight, ear length and sweetness while ear width, ear commercial value and sweetness were significant for specific combining ability by location interaction. Sweetness was found significant for both interactions. The first and fourth inbred lines had the most number of traits with good estimate of general combining ability. The first inbred is expected to improve days to tasseling, anthesis silking interval, ear width, ear circumference and sweetness while decreasing husk cover in a hybrid combination. The fourth inbred line would improve days to tasseling, days to silking, plant height, ear height, per ear weight and ear length but ears would be a bit tougher than the average. A total of 19 traits had higher variance of general combining ability than that of specific combining ability. Husk cover was 12.1 times higher. Plant height and number of tillers/plant had higher variance of specific combining ability.

The International Union for the Protection of New Varieties of Plants (UPOV) promotes an effective system of plant variety protection and encourages the development of new varieties of plants. This international convention was initiated to standardize the system efforts and strengthen policy. The establishment of cultivar discrimination system is very important to distinguish varieties between domestic and foreign agricultural products. It is necessary for the protection of breeders’rights. In addition, it will help for more efficient and quality management of plant breeding. This study was conducted to identify and group rice varieties based on agro-morphological characteristics such as plant height, panicle length, number of tillers, culm length, leaf length, leaf width, leaf pigments and flag leaf angles. Using these parameters, statistical analysis classified a total of 243 rice varieties bred in Korea into four groups. Most rice varieties did not exhibit anthocyanin pigments on the leaves particularly on the first leaf, leaf blade, leaf sheath and auricle, except for varieties classified as black rice. Results of phylogenetic and principal component analysis (PCA) indicated that these varieties formed three largely distinct clusters according to their ecotype and morphological differentiation. This result would be useful in rice varietal identification for the protection of breeders’variety rights.