Relative performance of white clover (Trifolium repens) cultivars and experimental synthetics under rotational grazing by beef cattle, dairy cattle and sheep

Assessment of the relative performance of white clover (Trifolium repens L.) cultivars, using multi-year and multi-location seasonal growth trials, is key to identification of material with specific and broad adaptation. This paper is based on a multi-year and multi-location study of 56 white clover entries comprising 14 commercial cultivars and 42 experimental synthetic lines evaluated for seasonal growth under rotational grazing across four locations in New Zealand over 4years. The four locations (and animals grazing) were: Kerikeri (beef cattle), Aorangi (beef cattle), Ruakura (dairy cattle), Lincoln (sheep). Significant (P<0.05) genotypic variation among the 56 entries, and genotype × year, genotype× location and genotype× season interactions, were estimated. We were able to identify cultivars and experimental synthetics with specific and broad adaptation to the three grazing management types. Cvv. AberDance, Apex, Demand, Prestige, Quartz and Riesling, with leaf size ranging from small to medium–large, showed highly above-average performance under sheep grazing. Synthetic lines 15 and 45 also had highly above-average performance under sheep grazing. Cvv. Legacy and Kopu II showed above-average performance under cattle and dairy grazing. Synthetics 15, 48, 49, 44, 22 and 18 and cv. Quartz had above-average performance under all three grazing managements. Synthetics 27, 33 and 38 had highly above-average performance across all three grazing managements and were superior to all 14 cultivars evaluated. Several of these superior synthetics are being tested across multiple grazing environments. Among the 14 cultivars evaluated, Legacy and Quartz showed superior seasonal growth performance across the three grazing managements. Quartz is being evaluated in several on-farm trials across temperate regions of the world.

Prioritisation of candidate genes in QTL regions for seed germination and early seedling growth in bread wheat (Triticum aestivum) under salt-stress conditions

Salinity and drought are major abiotic stresses affecting wheat (Triticum aestivum L.) production throughout the world, and discovery of loci for traits affecting yield under salinity may lead to the breeding for salt-tolerant plants. In the present study, 186 F10 recombinant inbred line (RIL) populations were evaluated under salt-stress conditions in order to identify main-effect and epistatic-effect quantitative trait loci (QTLs) for 15 traits in wheat during the germination and early-seedling stages. In total, 61 main-effect QTLs on 15 chromosomes and 21 epistatic interactions on 12 chromosomes were detected through composite interval mapping (CIM) and a mixed-model-based CIM method. Two major QTLs for primary-leaf fresh weight and coleoptile fresh weight were detected on chromosome (or linkage group) 5B2 and 2D, respectively, which contributed ~44% and 43% of the phenotypic variance. Additionally, 12 QTL clusters including different traits were detected on 1A1, 3A, 4A, 2B1, 3B, 5B1 and 2D1. Candidate genes were identified within QTL regions and gene ontology (GO) enrichment analysis was performed. In total, 9134 candidate genes were grouped into 274 GO terms (including 79 GO terms involved in the ‘biological process’ category). These genes directly or indirectly play a vital role such as lipid localisation, biological regulation, fatty acid biosynthetic process, cellular process, DNA conformation change, translational elongation, carbohydrate metabolic process, Fe ion homeostasis, hydrogen peroxide metabolic process, and pigment biosynthetic process at the germination and early-seedling stages under salt-stress conditions.