Genetic improvement for stress tolerance requires a solid understanding of biochemical processes involved with different physiological mechanisms and their relationships with different traits. The objective of this study was to demonstrate genetic variability in altered metabolic levels in a panel of six wheat genotypes in contrasting temperature regimes, and to quantify the correlation between those metabolites with different traits. In a controlled environment experiment, heat stress (35:28 ± 0.08°C) was initiated 10 days after anthesis. Flag leaves were collected 10 days after heat treatment to employ an untargeted metabolomics profiling using LC-HRMS based technique called IROA. High temperature stress produced significant genetic variations for cell and thylakoid membrane damage, and yield related traits. 64 known metabolites accumulated 1.5 fold of higher or lower due to high temperature stress. In general, metabolites that increased the most under heat stress (L-tryptophan, pipecolate) showed negative correlation with different traits. Contrary, the metabolites that decreased the most under heat stress (drummondol, anthranilate) showed positive correlation with the traits. Aminoacyl-tRNA biosysnthesis and plant secondary metabolite biosynthesis pathways were most impacted by high temperature stress. The robustness of metabolic change and their relationship with phenotypes renders those metabolites as potential bio-markers for genetic improvement.

Cover crops are a major focus of conservation agriculture efforts because they can provide soil cover and increase nutrient availability after their mineralization in cropping systems. To evaluate the effect of residue type and placement on rate of decomposition and carbon (C) and nitrogen (N) mineralization, residues from two food crops, maize (Zea mays L.) and common bean (Phaseolus vulgaris L.), and two promising cover crops, sunn hemp (Crotalaria juncea L.) and sorghum sudangrass (Sorghum bicolor [L.] Moench x S. bicolor var. Sudanese [Piper] Stapf) were used in a litterbag study in the Central Plateau region of Haiti from May to September, 2013. Residues were placed in litterbags at a rate equivalent to 3.25 Mg residue ha−1 either on the soil surface or buried at 15 cm to represent a tilled and no-tillage system, respectively. Initial C:N ratios were: maize > common bean > sorghum sudangrass > sunn hemp. Highest residue mass loss rates and C and N mineralization generally occurred in the reverse order. Overall, surface-placed residues decomposed more slowly with 40 and 17 % of initial residue mass of surface and buried residues, respectively, remaining at 112 days. Carbon and N mineralization was higher when residues were buried. Net N mineralization of buried residues was 0.12, 0.07, 0.06, and 0.03 g N g residue−1 for sunn hemp, sorghum sudangrass, maize, and common bean, respectively over 112 days. To achieve the goal of increasing nutrient supply while maintaining year-round cover, a combination of grass and legume cover crops may be required with benefits increasing over multiple seasons.

Since there are different ways to report moisture (as a decimal or as a percentage), and because the calculation seems intuitive, there is some confusion among agricultural professionals about how to adjust yield to a standardized moisture content. This 4-page publication aims to clarify the concept and themath. Written by Michael J. Mulvaney and Pratap Devkota, and published by the UF/IFAS Agronomy Department, May 2020.

Core Ideas: Carinata growth and yield was influenced more by row spacing than seeding rate. Rows spaced at 36 cm maximized carinata yield. Carinata branching was favored by wider row spacing. Carinata (Brassica carinata A. Braun) is an oilseed crop with potential as a winter crop in the southeastern United States to diversify crop rotations and provide biofuel production and livestock feed. The objective was to evaluate the effects of row spacing and seeding rate on carinata yield and oil composition. Field experiments were conducted in Jay and Quincy, FL, from 2013 to 2016 evaluating carinata growth, seed and oil yield, and oil composition grown in a factorial arrangement of four seeding rates (3, 6, 9, and 12 kg ha⁻¹) and four row spacings (18, 36, 53, and 89 cm). No interactions between seeding rate and row spacing were detected. Seeding rate did not influence any of the variables studied. In contrast, row spacing affected seed and oil yield, branch production, and pods per plant. Seed yield (ranked from highest to lowest) was 2761, 2286, 1851, and 1572 kg ha⁻¹ for rows spaced at 36, 18, 53, and 89 cm, respectively. Branching and pods per plant increased with row spacing. Neither seeding rate nor row spacing affected oil concentration and quality. Oil concentration averaged 40%, of which more than a third was erucic acid (C22:1). Protein concentration was 31%, and glucosinolate concentration was 93 μmol g⁻¹. The results of the present study demonstrated that carinata can be successfully grown in the southeastern United States, reaching yields and oil quality similar to those reported at other latitudes, and can be a source of biofuel, protein for animal feed, and cropping system diversification for growers.