Top management challenges and concerns for agronomic crop production in California: Identifying critical issues for extension through needs assessment

Soil acts as a sink for a number of organic and inorganic pollutants, through which these enter into the food chain and become a potential source of human diseases. Heavy metal (Cd, Cu, Cr, Fe, Ni, Pb, Zn) and metalloid (As, Sb) contamination of soil resources is increasing due to natural and anthropogenic activities. Currently, metal(loid) accumulation is one of the most serious environmental concerns owing to their toxicity to crops. Agronomic crops, mainly cereals (wheat, Triticum aestivum; maize, Zea mays; rice, Oryza sativa), are cultivated on large area and, thereby, are more vulnerable to metal(loid) toxicity, affecting crop growth (seed germination, root/shoot length, and biomass), physiology (water relation, pigmentation, photosynthetic machinery), and metabolic processes (reactive oxygen species (ROS), lipid peroxidation, protein degradation). However, to counter these anomalies, crops are equipped with antioxidants (CAT, POD, SOD, APX, GR, proline, phenolics) to detoxify metal-induced ROS and proteins (phytochelatins, PCs; metallothioneins, MTs) to sequester metal(loid)s. Thus, further insight into these processes is important to exploit better metal-contaminated areas for raising crops, generate revenue, and feed ever-increasing population. Therefore, we present an overview of heavy metal(loid) pollution in soil; their toxicity to cereals (wheat, maize, rice) at morphological, physiological, and cellular levels; and their tolerance mechanisms. At the end, we explore the symbiotic association of cereal crops to a microbe in scavenging metal toxicity.

Implications of weakening of the United States Geological Survey Pesticide National Synthesis Project for Weed Scientists

Environmental pollution with heavy metals has become a problem of major interest due to the harmful effects of metal ions that constantly evolve and generate serious threats to both the environment and human health through the food chain. Recognizing the imperative need for toxicological assessments, this study revolves around elucidating the effects of Pb(II) and Cu(II) ions on three plant species; namely, Medicago sativa L., Triticum aestivum L., and Zea mays L. These particular species were selected due to their suitability for controlled laboratory cultivation, their potential resistance to heavy metal exposure, and their potential contributions to phytoremediation strategies. The comprehensive phytotoxicity assessments conducted covered a spectrum of critical parameters, encompassing germination inhibition, seedling development, and broader considerations regarding ecosystem health. The key metrics under scrutiny included the germination rate, the relative growth of root and stem lengths, the growth inhibition index, and the tolerance index. These accurately designed experiments involved subjecting the seeds of these plants to an array of concentrations of PbCl2 and CuCl2 solutions, enabling an exhaustive evaluation of the phytotoxic potential of these metal ions and their intricate repercussions on these plant species. Overall, this study provides valuable insights into the diverse and dynamic responses of different plant species to Pb(II) and Cu(II) metal ions, shedding light on their adaptability and resilience in metal-contaminated environments. These findings have important implications for understanding plant-metal interactions and devising phytoremediation strategies in contaminated ecosystems.

We review the recent development of Conservation Agriculture (CA) for rice-based smallholder farms in the Eastern Gangetic Plain (EGP) and the underpinning research on agronomy, weed control, soil properties and greenhouse gas emissions being tested to accelerate its adoption in Bangladesh. The studies are based mostly on minimum soil disturbance planting in strip planting (SP) mode, using the Versatile Multi-crop Planter (VMP), powered by a two-wheel tractor (2WT). One-pass SP with the VMP decreased fuel costs for crop establishment by up to 85% and labour requirements by up to 50%. We developed strip-based non-puddled rice (Oryza sativa) transplanting (NPT) in minimally-disturbed soil and found that rice grain yield increased (by up to 12%) in longer-term practice of CA. On farms, 75% of NPT crops increased gross margin. For non-rice crops, relative yield increases ranged from 28% for lentil (Lens culinaris) to 6% for wheat (Triticum aestivum) on farms that adopted CA planting. Equivalent profit increases were from 47% for lentil to 560% for mustard (Brassica juncea). Moreover, VMP and CA adopting farms saved 34% of labour costs and lowered total cost by up to 10% for production of lentil, mustard, maize (Zea mays) and wheat. Effective weed control was obtained from the use of a range of pre-emergent and post-emergence herbicides and retention of increased crop residue. In summary, a substantial body of research has demonstrated the benefits of CA and mechanized planting for cost savings, yield increases in many cases, increased profit in most cases and substantial labour saving. Improvement in soil quality has been demonstrated in long-term experiments together with reduced greenhouse gas emissions.

Application of exogenous N fertilizers provides agronomic benefits but carries environmental liabilities. Managing benefits and liabilities of N-based fertilizers in conventional (CNV) and organic (ORG) cropping systems might be improved with better knowledge of nutrient dynamics, the generation of intrinsic N, and maintenance of soil organic matter. This study evaluated mineral N dynamics, yields, residue inputs, and change in soil organic C (SOC) and total N (TN) in strip-tilled, four-year crop rotations [corn (Zea mays L.)-soybean (Glycine max [L.] Merr.)-wheat under-seeded with alfalfa (Triticum aestivum L./Medicago sativa L.)-alfalfa] over eight years of production under CNV management using mineral-N (NO3NH4) and chemical pesticides or ORG management using organic-N (animal manure) and no chemical treatments. In ORG, N availability increased over time, but did not benefit ORG yields due to poor control of insects and weeds. Corn, soybean, and wheat grain yields were 1.9 to 2.7 times greater in CNV. In general, SOC was lost in CNV but did not change in ORG. Cumulative yield N removals exceeded cumulative fertilizer-N inputs by an average of 78% in CNV and 64% in ORG. These results indicated ORG management supported N availability by generating intrinsic N.

The PLATZ family is a novel class of plant-specific zinc finger transcription factors with important roles in plant growth and development and abiotic stress responses. PLATZ members have been identified in many plants, including Oryza sativa, Zea mays, Triticum aestivum, Fagopyrum tataricum, and Arabidopsis thaliana; however, due to the complexity of the alfalfa reference genome, the members of the PLATZ gene family in alfalfa (Medicago sativa L.) have not been systematically identified and analyzed. In this study, 55 Medicago sativa PLATZ genes (MsPLATZs) were identified in the alfalfa “Xinjiangdaye” reference genome. Basic bioinformatic analysis was performed, including the characterization of sequence lengths, protein molecular weights, genomic positions, and conserved motifs. Expression analysis reveals that 7 MsPLATZs are tissue-specifically expressed, and 10 MsPLATZs are expressed in all examined tissues. The transcriptomic expression of these genes is obvious, indicating that these MsPLATZs have different functions in the growth and development of alfalfa. Based on transcriptome data analysis and real-time quantitative PCR (RT-qPCR), we identified 22, 22, and 21 MsPLATZ genes that responded to salt, cold, and drought stress, respectively, with 20 MsPLATZs responding to all three stresses. This study lays a foundation for further exploring the functions of MsPLATZs, and provides ideas for the improvement of alfalfa varieties and germplasm innovation.

A field experiment was carried out at research farm, Institute of Pesticide Formulation Technology, Gurgaon over 2 years (2011 and 2012) to evaluate the bioefficacy of triasulfuron 20 WG (New source) in wheat [Triticum aestivum (L.) emend. Fiori & Paol.] and its residual effect on succeeding maize (Zea mays L.) crop. Different doses of triasulfuron 20 WG (New source) @ 75 and 100 g/ha; triasulfuron 20 WG (existing source) @ 75 and 100 g/ha; metsulfuron 20 WG @ 20 g/ha were applied at 35 days after sowing of crop with knapsack sprayer using flat fan nozzle @ 450 litres water/ha and 3 hand weedings at 15 days interval after emergence of the crop in weed free check. The effect of above mentioned treatments on weed density, weed biomass and weed control index (WCI %) were recorded at 60 days after application (DAA) against broad leaved weeds in wheat fields. The results indicated that the main broad-leaved weeds in wheat field were Chenopodium album L., Anagallis arvensis L., Melilotus sp., Rumex sp. and Lathyrus aphaca L. Metsulfuron 20 WP @ 20 g/ha and existing source of triasulfuran 20 WG @ 75 g/ha was least effective against broad leaf weeds. New source of triasulfuran 20 WG @ 100 g/ha was most effective in respect of weed control and dry-matter accumulation by weeds. Grain yield of wheat with the use of triasulfuron 20 WG (New source) @ 100 g/ha was 3.96 and 3.95 t/ha during first and second year of experimentation, which was the highest among the herbicide formulation. No carry over effect of these her- bicides was observed on succeeding maize.

BLAST (Basic Local Alignment Search) analyses of Hordeum chilense RAPD markers have shown DNA sequence similarities with several plant genes. Biologically significant hits were scored for: plastocianin (Hordeum vulgare), alpha-gliadin (Triticum aestivum), Grandel-6 retrotransposon (Zea diploperennis), retrofit (gag/pol) copia-like, transposon-like element (Oryza longistaminata), copia-like retrotransposon Hopscotch polyprotein (gag/pol) (Zea mays) and several retrotransposons/retroelements from other species (Arabidopsis thaliana, Oryza sativa, Pisum sativum and Zea mays). Statistically significant hits also included endochitinase (Brassica napius), ribulose-1,5-bisphosphate carboxylase (Euglena gracilis), piruvate, orthophosphate dikinase (Flaveria trinervia), and an ORF flanked by ARS sequences (Triticum aestivum). Interestingly, it was also found that the currently recommended BLAST algorithm (version 2.0.11; gapped) at <http://www.ncbi.nlm.nih.gov> did not produce any biologically significant hits, whereas the previous version (1.4.11; ungapped) did generate biologically significant results. Thus, we suggest using the new BLAST 2.0.x when strong homologies are expected in short sequence stretches between closely related species. In other instances (and particularly when searching for lower similarities, yet spanning significantly larger stretches between more distant species), the BLAST 1.4.x could yield additional results. BLAST searches are valuable tools to identify and clone DNA sequences of interest, with applications in Marker-Assisted Selection (MAS) and wheat introgression.

Although Melanaphis sacchari Zehntner (Hemiptera: Aphididae) is known worldwide for its injury to sugarcane, Saccharum officinarum L., and sorghum, Sorghum bicolor (L.) Moench, M. sacchari is reported to infest several plants in the family Poaceae, including important agronomic crops. It is not clear how M. sacchari interacts with other crops in the Louisiana agroecoscape but there is potential for these plants to be bridging hosts prior to sorghum colonization. Thus, this study determined the population dynamics of M. sacchari on sugarcane, sorghum, rice (Oryza sativa L.), sweetpotato (Ipomea batatas L.), maize (Zea mays L.), Johnsongrass (S. halepense L.), and wheat (Triticum aestivum L.) using life table studies. Melanaphis sacchari was able to complete its life cycle on sorghum, sugarcane, rice, and wheat, having the highest intrinsic rate of increase (rm) on sorghum (0.466). Population growth was negative on rice (rm = -0.020) and intermediately positive on sugarcane and Johnsongrass. The results demonstrate that there is the potential for multiple host use within the agricultural landscape. Using the information collected from this study, population estimations on host plants demonstrate that M. sacchari populations will increase more rapidly on sorghum than on the other host plants.

Tillage is decreasing globally due to recognized benefits of fuel savings and improved soil health in the absence of disturbance. However, a perceived inability to control weeds effectively and economically hinders no-till adoption in organic production systems in the Upper Midwest, USA. A strip-tillage (ST) strategy was explored as an intermediate approach to reducing fuel use and soil disturbance, and still controlling weeds. An 8-year comparison was made between two tillage approaches, one primarily using ST the other using a combination of conventional plow, disk and chisel tillage [conventional tillage (CT)]. Additionally, two rotation schemes were explored within each tillage system: a 2-year rotation (2y) of corn (Zea mays L.), and soybean (Glycine max [L.] Merr.) with a winter rye (Secale cereale L.) cover crop; and a 4-year rotation (4y) of corn, soybean, spring wheat (Triticum aestivum L.) underseeded with alfalfa (Medicago sativa L.), and a second year of alfalfa. These treatments resulted in comparison of four main management systems CT-2y, CT-4y, ST-2y and ST-4y, which also were managed under fertilized and non-fertilized conditions. Yields, whole system productivity (evaluated with potential gross returns), and weed seed densities (first 4 years) were measured. Across years, yields of corn, soybean and wheat were greater by 34% or more under CT than ST but alfalfa yields were the same. Within tillage strategies, corn yields were the same in 2y and 4y rotations, but soybean yields, only under ST, were 29% lower in the fertilized 4y than 2 yr rotation. In the ST-4y system yields of corn and soybean were the same in fertilized and non-fertilized treatments. Over the entire rotation, system productivity was highest in the fertilized CT-2y system, but the same among fertilized ST-4y, and non-fertilized ST-2y, ST-4y, and CT-4y systems. Over the first 4 years, total weed seed density increased comparatively more under ST than CT, and was negatively correlated to corn yields in fertilized CT systems and soybean yields in the fertilized ST-2y system. These results indicated ST compromised productivity, in part due to insufficient weed control, but also due to reduced nutrient availability. ST and diverse rotations may yet be viable options given that overall productivity of fertilized ST-2y and CT-4y systems was within 70% of that in the fertilized CT-2y system. Closing the yield gap between ST and CT would benefit from future research focused on organic weed and nutrient management, particularly for corn.

Frost‐seeding a legume into an established stand of winter wheat (Triticum aestivum L.) or interseeding a legume into a small grain at planting has potential to provide the benefits of a legume green manure while still allowing for the harvest of a revenue‐producing crop. Field studies were conducted at three Michigan locations to quantify N accumulation by alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) frost‐seeded into winter wheat or interseeded with oat (A vena sativa L.) and to evaluate the response of a subsequent corn (Zea mays L.) crop to legume and fertilizer N. Cropping sequences included corn following either wheat, wheat frost‐seeded with a legume, oat, or oat interseeded with a legume. Corn was planted either no‐till following wheat or conventionally (moldboard plow) following oat. Frost‐seeding and interseeding alfalfa and red clover had no effect on small grain yield, and stands of alfalfa and red clover were adequate (&gt;13 plants/sq ft) even though N fertilizer had been applied to the small grains. Nitrogen accumulation did not differ among alfalfa or red clover cultivars, and averaged 80, 50, and 116 lb N/acre for alfalfa; and 96, 99, and 176 lb N/acre for red clover frost‐seeded into winter wheat at the three locations. When interseeded with oat, alfalfa contained an average of 44 lb N/acre and red clover contained an average of 33 lb N/acre prior to fall plowing. Corn response to the frost‐seeded legumes differed among locations due primarily to differences in precipitation during the weeks just prior to and following corn planting. When soil water was adequate, corn grain yields following the small grain seeded with a legume were 4 to 62% greater than following the small grain without the legume. With below‐normal precipitation following corn planting, corn grain yields in the legume systems were reduced by 3 to 27%, primarily due to delayed and reduced emergence. Fertilizer replacement values based on grain yield ranged from 0 to 49 lb N/acre for alfalfa and from 0 to 113 lb N/acre for red clover. Response of corn to the preceding legume differed by year, location, and seeding method.

The objectives of this study were to determine the efficacy and risk of controlling weeds at reduced herbicide rates under various environmental and biotic conditions, through analysis of published data on the use of below-labeled rates of herbicides. A database was established by extracting information from previously published papers on weed control at below-labeled rates of herbicides in crop production systems over large geographical and temporal scales. The database was then analyzed to evaluate the efficacy and risk of using herbicides at various reduced rates under different management systems. Using below-labeled herbicide rates in conjunction with interrow cultivation is an effective way of reducing herbicide input in agricultural systems while maintaining satisfactory weed control. There are greater opportunities for herbicide reduction using preemergence (PRE) than preplant incorporated (PPI) or postemergence (POST) herbicides, in coarse-textured than in fine-textured soils, and in corn than in soybean or wheat. The success of reducing herbicide rates does not depend on whether the herbicides are applied in conventional or conservation tillage systems or whether they are used with or without adjuvants. The above conclusions are based on studies conducted in experimental fields where weed pressures may be subjectively chosen to be high. Greater potential for herbicide reduction may exist at locations or in cropping systems were weed pressure is low.Nomenclature: Corn, Zea mays L.; soybean, Glycine max (L.) Merr.; wheat, Triticum aestivum L.Additional index words: Database, herbicides, reduced rates, weed control efficacy.Abbreviations: POST, postemergence; PPI, preplant incorporated; PRE, preemergence.

The power and versatility of genome editing tools in crop improvement

A field study was conducted on upland soils for six years to determine interactive effects of winter wheat (Triticum aestivum L.) cover crop, organic and inorganic soil amendments on grain yields and nutrient utilizations in a no-till corn (Zea mays)-soybean (Glycine max) rotation. Experimental design was a split-plot arrangement with four replicates. Cover crops were the main plots and fertilization treatments used as sub-plot. Fertilization treatments included an unfertilized control, poultry litter, poultry litter (PL) plus flue gas desulfurization (FGD) gypsum and inorganic N fertilizer applied every other year to corn. Corn grain yield and grain N and P uptake were greater with PL than inorganic fertilizer in 2014 and 2016. Addition of FGD gypsum to PL significantly increased corn grain yield by 15% in 2016. Cover crop increased corn and soybean grain yields in a year with less seasonal rainfall possibly by conserving soil moisture.

In recent years there has been an increase in consumers demands for mungbean, alfalfa, soybean, radish and other seed sprouts (Rosas and Escartin, 2000) that are usually eaten raw in salads or in sandwiches. Seed sprouts have been part of the human diet since old times in countries such as Japan where they are widely consumed. Tthe interest in consuming fresh green sprouts has extended all over the world because they are considered to provide health benefits (Rosas and Escartin, 2000). A great variety of seed sprouts can be found at present in the market, such as adzuki bean (Phaseolus angularis), alfalfa (Medicago sativa), broccoli (Brassica oleracea convar. botrytis), cress (Lepidium sativum), lentil (Lens culinaris), mung bean (Phaseolus aureus), soybean (Glycine max), white mustard (Sinapis alba), green and yellow pea (Pisum sativum), onion (Allium cepa), radish (Raphanus sativus), rice (Oryza sativa L.), rye (Secale cereale), sesame (Sesamum indicum), sunflower (Helianthus annuus) and wheat (Triticum aestivum), although the most popular are alfalfa, soybeans, mung beans and raddish (Taormina et al., 1999). Seed sprouts are usually eaten raw in salads or in sandwiches, and concerns for the safety of these raw foods have increased lately. Sprouts are grown from seeds placed in environmentally controlled, hydroponic conditions and incubated in warm, moist, nutrient-rich conditions, which are ideal environments for microbial growth. The seeds usually carry microbial loads comprised between 3 and 6 log CFU/g, including pseudomonads and enterobacteriaceae as main components (Andrews et al., 1982; Prokopowich and Blank, 1991; Robertson et al., 2002; Splittstoesser et al., 1983). The bacterial load increases rapidly during the sprouting process, reaching from 6 to 8 log CFU/g after two days in one study (Fu et al., 2001) and between 7.8 and 8.8 in another (Weiss et al., 2007). Other reports have indicated final counts of up to 8-9 log CFU/g in commercial sprouts (Patterson and Woodburn, 1980; Prokopowich and Blank, 1991). In addition, the pathogenic bacteria can survive on sprouts through the typical refrigerated shelf life of the products (Harris et al., 2003). Recent studies indicate that pathogenic bacteria can survive both on and in plant tissues (Lynch et al., 2009). For example, when alfalfa seeds contaminated with Escherichia coli O157 or with Salmonella are sprouted, the bacteria enter the growing sprout, and appear throughout the deep tissues of the young plants (Itoh et al.,