Evaluation of simulated hail damage on seed yield and agronomic traits in canola (Brassica napus L.)

Natural hail can cause significant damage on seed yield and yield contributing traits of canola (Brassica napus L.). Hail damage can be assessed by (i) type of damage such as stand reduction, stem cut-off, and leaf defoliation, (ii) level of damage, and (iii) plant growth stage. In this research, a simulated hail study was performed by applying nonuniform stand reduction treatments on canola grown in North Dakota, USA, over 5 site-years, in 2017 and 2018. The experiment was a randomized complete block design 4 × 5 factorial arrangement with four growth stages, rosette, bolting, 50%, and 90% flowering, when five stand reduction treatments were applied at 0 (control), 25%, 50%, 75%, and 90%. Growth stage and stand reduction were significant for seed yield where yield decreased as stage of treatment progressed and level of stand reduction increased. Regression equations were developed to estimate the seed yield reduction at each growth stage as stand reduction increased. Stand reduction also affected other traits where plant height was reduced as stand reduction increased, whereas 1000-seed weight, primary branches plant−1, secondary branches plant−1, pods plant−1, seed yield plant−1, plant biomass plant−1, and harvest index plant−1 increased as stand reduction increased. As growth stage progressed the number of primary branches plant−1, secondary branches plant−1, pods plant−1, and harvest index plant−1 decreased, whereas 1000-seed weight increased. The findings of differential yield losses by stand reduction will help producers and crop adjusters to assess the severity of hail damage in canola.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Cold temperature delays wound healing in postharvest sugarbeet roots

Storage temperature affects the rate and extent of wound-healing in a number of root and tuber crops. The effect of storage temperature on wound-healing in sugarbeet (Beta vulgaris L.) roots, however, is largely unknown. Wound-healing of sugarbeet roots was investigated using surface-abraded roots stored at 6 and 12 °C for 28 days. Surface abrasions are common injuries of stored roots, and the storage temperatures used are typical of freshly harvested or rapidly cooled roots. Transpiration rate from the wounded surface and root weight loss were used to quantify wound healing. At 12 °C, transpiration rate from the wounded surface declined within 14 days and wounded roots lost weight at a rate similar to unwounded controls. At 6 °C, transpiration rate from the wounded surface did not decline in the 28 days after injury, and wounded roots lost 44% more weight than controls after 28 days storage. Melanin formation, lignification, and suberization occurred more rapidly at 12 °C than at 6 °C, and a continuous layer of lignified and suberized cells developed at 12 °C, but not at 6 °C. Examination of enzyme activities involved in melanin, lignin, and suberin formation indicated that differences in melanin formation at 6 and 12 °C were related to differences in polyphenol oxidase activity, although no relationships between suberin or lignin formation and phenylalanine ammonia lyase or peroxidase activity were evident. Wound-induced respiration was initially greater at 12 °C than at 6 °C. However, with continued storage, respiration rate of wounded roots declined more rapidly at 12 °C, and over 28 days, the increase in respiration due to injury was 52% greater in roots stored at 6 °C than in roots stored at 12 °C. The data indicate that storage at 6° C severely slowed and impaired wound- healing of surface-abraded sugarbeet roots relative to roots stored at 12°C and suggest that postharvest losses may be accelerated if freshly harvested roots are cooled too quickly

Postharvest jasmonic acid treatment of sugarbeet roots reduces rot due to Botrytis cinerea, Penicillium claviforme, and Phoma betae

Although jasmonic acid (JA) and JA derivatives are known to activate plant defense mechanisms and provide protection against postharvest fungal diseases for several horticultural crops, JA's ability to protect sugarbeet (Beta vulgaris L.) roots against common causal organisms of storage rot is unknown. To determine the potential of JA to reduce rot due to three common sugarbeet storage pathogens, harvested roots were treated with JA concentrations of 0.01, 0.1, 1, 10, or 100 μM, inoculated with Botrytis cinerea, Penicillium claviforme, or Phoma betae, and evaluated for the severity of rot symptoms after incubation at 20 °C and 90% relative humidity. JA concentrations of 0.01–100 μM significantly reduced rot due to all three pathogens. All concentrations of JA provided statistically equivalent control against B. cinerea and P. betae, and reduced the amount of rotted tissue due to these pathogens by an average of 51 and 71%, respectively. Against P. claviforme, JA concentrations of 0.01–10 μM were equally effective and reduced rot by an average of 44%, while an increase in JA concentration to 100 μM reduced rot by 65%. Against all three pathogens, JA treatment did not affect the incidence of infection, but reduced rot by reducing the progression of disease symptoms in root storage tissue

Postharvest salicylic acid treatment reduces storage rots in water-stressed but not unstressed sugarbeet roots

Exogenous application of salicylic acid (SA) reduces storage rots in a number of postharvest crops. SA's ability to protect sugarbeet (Beta vulgaris L.) taproots from common storage rot pathogens, however, is unknown. To determine the potential of SA to reduce storage losses caused by three common causal organisms of sugarbeet storage rot, freshly harvested roots were treated with 0.01, 0.1, 1.0 or 10 mM SA, inoculated with Botrytis cinerea, Penicillium claviforme, or Phoma betae, and evaluated for the severity of rot symptoms after incubation at 20 °C and 90% relative humidity. Roots were obtained from plants that received sufficient water or were water-stressed prior to harvest. Roots from water-stressed plants were included since water-stress increases sugarbeet root susceptibility to storage rot and SA mitigates drought effects in other plant species. SA at concentrations of 0.01–10 mM had no effect on the severity of storage rot caused by B. cinerea, P. claviforme, or P. betae in roots from plants that received sufficient water prior to harvest. However, SA at these same concentrations reduced the severity of rot symptoms for all three pathogens in roots from plants that were water stressed before harvest. For water-stressed roots, all concentrations of SA produced statistically equivalent reductions in the weight of rotted tissue for each pathogen, and on average, SA reduced rot severity due to B. cinerea, P. claviforme, and P. betae by 54, 45, and 58%, respectively. SA reduced rot from all three pathogens by reducing lesion size, but did not affect the incidence of infection. The ability of SA to reduce rot severity in water-stressed roots, but not in roots that received sufficient water before harvest suggests that SA alleviated the negative impact of water stress but did not directly protect sugarbeet roots against storage rots

Glycolysis Is Dynamic and Relates Closely to Respiration Rate in Stored Sugarbeet Roots

Although respiration is the principal cause of the loss of sucrose in postharvest sugarbeet (Beta vulgaris L.), the internal mechanisms that control root respiration rate are unknown. Available evidence, however, indicates that respiration rate is likely to be controlled by the availability of respiratory substrates, and glycolysis has a central role in generating these substrates. To determine glycolytic changes that occur in sugarbeet roots after harvest and to elucidate relationships between glycolysis and respiration, sugarbeet roots were stored for up to 60 days, during which activities of glycolytic enzymes and concentrations of glycolytic substrates, intermediates, cofactors, and products were determined. Respiration rate was also determined, and relationships between respiration rate and glycolytic enzymes and metabolites were evaluated. Glycolysis was highly variable during storage, with 10 of 14 glycolytic activities and 14 of 17 glycolytic metabolites significantly altered during storage. Changes in glycolytic enzyme activities and metabolites occurred throughout the 60 day storage period, but were greatest in the first 4 days after harvest. Positive relationships between changes in glycolytic enzyme activities and root respiration rate were abundant, with 10 of 14 enzyme activities elevated when root respiration was elevated and 9 glycolytic activities static during periods of unchanging respiration rate. Major roles for pyruvate kinase and phosphofructokinase in the regulation of postharvest sugarbeet root glycolysis were indicated based on changes in enzymatic activities and concentrations of their substrates and products. Additionally, a strong positive relationship between respiration rate and pyruvate kinase activity was found indicating that downstream TCA cycle enzymes were unlikely to regulate or restrict root respiration in a major way. Overall, these results establish that glycolysis is not static during sugarbeet root storage and that changes in glycolysis are closely related to changes in sugarbeet root respiration