Crops, Volume 3, Issue 4 (December 2023) – 7 articles

In current markets, the primary uses for soybean seeds are in products derived from their oil or protein content. However, growers are compensated based on seed yield, so a more valuable crop is one that does not compromise on yield when compared with existing options, with an optimum combination of protein and oil. A negative correlation of seed protein with seed yield and oil makes the simultaneous improvement of these traits difficult but not impossible through conventional breeding. Selections of lines with exceptional yield and seed composition were made from two recombinant inbred line (RIL) soybean mapping populations to identify high protein and/or high oil lines with yields comparable to elite cultivars. The performance of these RILs was evaluated in multiple environments, and several genotypes were identified with yields comparable to those of high-yielding check cultivars with seed protein and/or oil content superior to the checks. These genotypes will provide breeders with additional sources of germplasm for continuing efforts to improve seed composition traits without compromising seed yield and provide growers with more profitable cultivars. Full article

Fusarium head blight (FHB) is a devastating fungal disease of hexaploid wheat (Triticum aestivum). Several genetic loci were previously identified that control FHB resistance in wheat, including Fhb1. Fhb7, a major QTL conferring resistance to FHB, controlling for mycotoxin deoxynivalenol (DON) production, has been introgressed into soft red winter wheat (SRWW). As an exotic QTL, Fhb7 is associated with linkage drag, affecting agronomic and end-use quality performance. This study outlines a breeding strategy for introducing and pyramiding Fhb7 into SRWW breeding populations that already possessed Fhb1 and harbored some additional disease-resistance genes. In addition to the Fhb1-Fhb7 pyramiding, we developed gene-based markers for both genes and examined them on 57 SRWW breeding lines. Our data showed that 15 out of 57 breeding lines possessed both Fhb1 and Fhb7 resistant alleles. Two years of phenotypic data from the inoculated and misted irrigation field showed that the combination of Fhb1-Fhb7 lowers mycotoxin DON accumulation in kernels, which provides protection for end-users and the milling industry. The Fhb gene-pyramided lines, with the additional regionally important disease resistance genes, produced in this breeding pipeline showed reasonable agronomic traits and can be used in crossing programs for the widespread introgression in elite wheat cultivars. Full article

Plants of the genus Physalis are of economic interest because of their fleshy edible fruits with high nutritional value. Some species have high medicinal value with a long history of ethno-medicinal use to treat diverse diseases. There is therefore a need to correctly discriminate the different species of Physalis for proper utilization. Although most Physalis species have unique morphologies, their vegetative stages are identical, making it difficult to accurately identify them based on morphological characteristics. DNA barcoding has the potential to discriminate species accurately. In this study, ribulose bisphosphate carboxylase large (rbcL) and internal transcribed spacer 2 (ITS2) regions were used to discriminate Physalis species and to reveal their phylogenetic relationships and genetic diversity. Physalis plant samples were collected from seven counties in Kenya based on the availability of the germplasm. The voucher specimens were identified using the botanical taxonomy method and were deposited in the University of Nairobi herbarium. Genomic DNA was isolated from leaf samples of 64 Physalis accessions and used for PCR amplification and the sequencing of rbcL and ITS2 barcode regions. The discriminatory ability of the barcodes was based on BLASTn comparison, phylogenetic reconstruction and cluster analysis, and the determination of inter- and intra-specific distances. The nucleotide polymorphism, genetic diversity and distance of the identified Physalis species were determined using DnaSP and MEGA 11.0 software. Species discrimination was more robust using ITS2 sequences. The species identified and discriminated by ITS2 sequences were Physalis purpurea, Physalis peruviana and Physalis cordata. The rbcL sequences were only able to identify Physalis to the genus level. There was high interspecific and low intraspecific divergence within the identified Physalis species based on ITS2 sequences. The ITS2 barcode is an ideal DNA barcode for use in the discrimination of species, as well as in genetic diversity studies of Physalis accessions in Kenya. Full article

Parthenium weed (Parthenium hysterophorus L.) is an emerging production constraint in many summer crops including sorghum (Sorghum bicolor L. Moench), but limited control options are available. In this field study, the efficacy of sole and sequential applications of a pre-emergence (pendimethalin) and a post-emergence (bromoxynil) herbicide was evaluated for parthenium weed control in grain sorghum over two years. Pendimethalin or bromoxynil alone could only provide 54% and 63% control, whereas their sequential application provided 86% control of parthenium weed over the weedy treatment. The sorghum plants in pendimethalin followed by bromoxynil treatment had the highest leaf fresh weight per plant, plant dry biomass, plant height, and the number of heads among the herbicide treatments. Sorghum fresh forage yield, dry fodder yield, 1000-grain weight, and grain yield were highest in the weed-free treatment followed by the pendimethalin followed by (fb) bromoxynil treatment. Overall, the herbicide treatment performance was in an order of pendimethalin fb bromoxynil > bromoxynil > pendimethalin for weed control and sorghum yield improvement. These results suggest that pendimethalin followed by bromoxynil may provide acceptable control (>85%) of parthenium weed and may improve sorghum grain yield (up to 23%). Full article

Amid a rapidly growing global population and increasing threats to crop yields, this review focuses on Speed Breeding (SB) in crop genetics. It traces SB’s development from carbon arc lamp experiments 150 years ago to its modern use with LED technology which significantly accelerates breeding cycles. SB has applications in genetic mapping, genetic modification, and trait stacking, enhancing crop resilience by leveraging allelic diversity. It aligns well with breeding methods like single plant selection and single seed descent. The integration of SB with gene editing, genotyping, and genomic selection holds great promise. However, SB faces challenges related to infrastructure, genotypic variations, and potential stress responses. In summary, SB is a powerful and promising approach to address food security concerns and advancing crop genetics. Full article

Pearl millet (Pennisetum glaucum (L.) R. Br.) and cowpea (Vigna unguiculata L. Walp.) are well-adapted to semiarid regions. A two-year study at New Mexico State University’s Rex E. Kirksey Agricultural Science Center at Tucumcari, NM, USA, compared monoculture pearl millet and cowpea with their mixtures in various row arrangements in four randomized complete blocks each year. Treatments included monoculture pearl millet (millet) and cowpea (cowpea), pearl millet and cowpea mixture planted in the same row (millet–cowpea), the species planted in alternate rows (millet–cowpea 1:1), the species planted in two adjacent rows alternating between species (millet–cowpea 2:2), and the species planted in four adjacent rows alternating between species (millet–cowpea 4:4), Mixture neutral detergent fiber (NDF) was reduced i millet–cowpea 1:1 and millet–cowpea 2:2 compared to millet (673, 662, 644, 646, and 666 g NDF kg⁻¹ for millet, millet–cowpea, millet–cowpea 1:1, millet–cowpea 2:2, and millet–cowpea 4:4, respectively, LSD = 18, p ≤ 0.05). Crude protein tended to be increased in millet–cowpea 2:2. Based on these results two rows of cowpea alternated with two rows of pearl millet, all spaced at 15 cm and harvesting for hay at the pearl millet boot stage likely optimizes the compromise of DM yield and the nutritive value of the mixture. Full article

Tomato (Solanum lycopersicum L.) had almost 190 million tonnes produced in 2021. Tomato fruit suffer losses of up to 50% during harvest and transport, which causes financial hardship, reduces the amount of food available and causes environmental harm. Calcium plays an important role in cell wall strength. This work assessed the use of a calcium transport stimulant (MCAS) to increase the firmness of tomato fruit in the laboratory and the foliar application to tomato plants. Then, handling damage was simulated. In the laboratory, the calcium with MCAS significantly increased the fruit firmness compared to the untreated and calcium without MCAS, which were not significantly different. When calcium with MCAS was applied to tomato plants foliarly before harvest, the calcium with MCAS-treated fruit were significantly firmer than the untreated or calcium without MCAS-treated fruit for up to 10 weeks after harvest, and this was achieved by applying only 0.91 kg ha⁻¹ calcium. Finally, when fruit were exposed to a simulated drop, the calcium with MCAS-treated fruit remained firmer than the undamaged fruit or dropped fruit with calcium without MCAS. Calcium with MCAS could significantly increase the fruit firmness and increase the shelf-life of tomatoes while applying less calcium. Full article