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Abstract
Numerical rating scales and their descriptive equivalents for firmness, visual quality, decay, butt discoloration, wilting, and other defects of lettuce (Lactuca sativa L.) are described. Also presented are scoring systems for brown stain, russet spotting, and rusty-brown discoloration of crisphead lettuce that consider severity of lesions, proportion of leaf affected and number of leaves affected in a head.
Abstract
Growth-regulating substances have been used extensively on horticultural crops to increase fruit set and prevent fruit drop. Several investigators have observed that preharvest application of growth regulators such as 2,4,5-trichlorophenoxyacetic acid may affect fruit maturity and ripening (Stewart, 4). This raised the question about the effects of the postharvest treatment of fruits with grbwth regulators.
Abstract
Chlorotic silver maples (Acer saccharinum L.) were treated during bud break with soil-applied EDDHA (ethylenediaminedi-0-hydroxyphenylacetate) and trunk implants of encapsulated FAC (ferric ammonium citrate), EDTA (ethylenediaminetetracetate) and DTPA (diethylenetriaminepentaacetate). Foliar levels of Ca were higher in chlorotic than green tissue. Chlorophyll levels and twig growth of treated trees were not significantly different from chlorotic controls after treatment. Soil Fe levels were different under chlorotic and green control plants. However, foliar Fe analyses demonstrated that Fe levels were not different in green and chlorotic leaf tissue.
Abstract
Ten flowering annuals were greenhouse-grown and irrigated with four levels of saline water [electrical conductivities (EC) = 0.8, 1.5, 3.0, 4.5 dS·m−1] to determine their response to increased salinization. Twelve different parameters were monitored at the end of an 8-week period. All 10 species differed in their response to salinization. The relative number of flowers and the relative maximum flower diameter at harvest decreased significantly for six of ten and seven of nine species, respectively, with increased salinity. A salt tolerance scale was devised that best described their response to salinity. The parameters selected were dry weight, plant height, number of flowers, and maximum flower diameter. Cosmos (Cosmos bipinatus Cav. ‘Sunny Gold’) was rated very sensitive for all four parameters. Following Cosmos, the rating changed and so did the sequence, depending on the parameter being considered. Both petunias (Petunia hybrida Linn. ‘White Cascade’ and ‘Challenger White’) and dianthus (Dianthus chinensis Linn. ‘Princess White’) were the only species rated very tolerant for all four parameters.
Abstract
Temperature of fruit of Vitis labrusca L. cv. Concord at harvest was the primary factor governing the rate of postharvest quality changes. Fruit harvested at mid-day at 32°C remained at that temperature inside a bulk pallet box for 72 hours, regardless of diurnal temperature fluctuations. Without addition of SO2, alcohol concentration steadily increased after 12 hours holding the mechanically-harvested grapes in a bulk pallet box and reached 3% after 72 hours. Loss of soluble solids began immediately after harvest and after 72 hours, 44% of the soluble solids present at the time of harvest had been lost. Addition of S02 at harvest or no later than 6 hours after harvest aided in slowing postharvest deterioration. The addition of 80 or 160 ppm SO2 to a bulk pallet box of grapes mechanically harvested at a temperature of 35° was as effective in retarding postharvest deterioration of the quality attributes determined in this study as was harvesting at 24°. Harvesting at a cool temperature (24°) and SO2 addition will allow for extended holding of the raw product with minimal alcohol production and raw product quality loss.
Abstract
Naphthaleneacetic acid (NAA) was applied to 10-year-old ‘Concord’ grapevine trunks at 0, 2, 4, and 8% concentrations. Best control of shoots on trunks was obtained with the 4 and 8% concentrations with no visual foliar injury or detrimental effects on yield, vine size, or fruit quality. One application of NAA at 8% reduced the number of trunk shoots for 3 years, but 100% control was obtained only in the year of application.
Abstract
Succinic acid-2, 2-dimethylhydrazide (daminozide), at rates of 0, 1000, and 2000 ppm, was applied between first and peak bloom to 2 adjacent ‘Concord’ (Vitus labrusca L.) vineyards: a 9-year-old vineyard with a histoty of good fruit set and a 19-year-old vineyard with a history of poor fruit set. No significant yield increase was obtained in the young vineyard, but there was a tendency for lower soluble solids and poorer juice color due to daminozide. Yields were increased by 2.4 and 3.3 MT/ha by 1000 and 2000 ppm daminozide, respectively, in the older vineyard with no significant effect on juice quality. The one-year increase in yield of grapes in the older vineyard was accompanied by a reduction in vine size.
Muscadine grapes (Vitis rotundifolia Michx.), native to the southeastern United States, have a distinct flavor, and grocers are interested in marketing them as table grapes. Two studies using 'Fry' muscadines were conducted to assist the muscadine industry in providing quality table grapes. Study 1 (1998 and 1999) evaluated density sorting and relationships between maturity, color, soluble solids, firmness, shelf life, and sensory evaluation of grapes. Study 2 (1998) determined the effect of storage on quality attributes of different maturities of grapes and evaluated use of polyethylene bags to extend their storage. Density separation successfully sorted grapes by maturity. Muscadine berry color may allow for visual or electronic sorting to eliminate immature fruit. Sensory panelists could distinguish differences in maturities for all sensory attributes. In 1999 maturities 3 and 4 (≈24-33 soluble solids: acid ratio) were preferred overall by panelists. As maturity increased, soluble solids and pH increased, and acidity decreased. Firmness decreased as maturity and storage at 2 °C increased. Percent decay increased with maturity and storage time. Grapes stored in polyethylene bags had reduced decay. A chart developed from the 1999 data related berry color to soluble solids: acid ratio, soluble solids, tartaric acid, and pH. Data from these studies can be used by industry to establish harvest parameters and enhance marketability of 'Fry' muscadine grapes.
Nineteen flowering landscape species were sprinkle irrigated with either reuse water or fresh water, with an additional treatment of reuse water plus shade (solar radiation reduced by 24%), for 113 days during late summer and early fall in southern Nevada. The species selected were common to mixed landscape areas on golf courses in southern Nevada transitioning to reuse water. An index of visual damage (IVD) was assessed, along with an assessment of flower production, canopy temperature, tissue ion analysis and spectral reflectance. The IVD values separated based on species (p < 0.001), treatment (p < 0.001) and by a species by treatment interaction (p < 0.001). Irrigating with reuse water plus shade reduced the IVD compared to the reuse without shade in 7 of the 19 species (p < 0.05). When IVD values were included for all species, 40% of the variation in the IVD values could be accounted for if N, B, Ca, Mg, Na, and Zn were included in the regression equation. Higher r 2 values were obtained when individual species were isolated, with regression equations differing based on tissue ion combinations [e.g., ice plant (Mesembryanthemum crystallinum L.) r 2 = 0.81 IVD↑, Na↓, Mn↑]. Three vegetation indices chlorophyll index (CHL), red/far red (R/FR) and water band index/normalized difference vegetation index (WBI/NDVI)) accounted for 51% of the variation in the IVD values. As much as 72% of the variation in vegetation indices could be accounted for based on tissue ion concentrations when separated based on treatment, with Na being the only common ion in all of the highest correlations. Flower production was highest in the reuse plus shade treatment in all 13 species flowering during the experimental period, with as much as 86% of the flower production variation driven by different tissue ion concentrations [purple cup (Nierembergia hippomanica), r 2 = 0.86, flowers↑, Mn↑, Zn↓]. Nine of the nineteen species had acceptable levels of foliar damage (IVD < 2.0). We believe that if the spray irrigation can be minimized (bubblers/drip) and/or partial shade provided, through multi-story landscape designs, a more favorable response will be observed.
Irrigation ponds on nine golf courses in southern Nevada were monitored for water quality over a 1600-day period. Three of the golf courses were fresh water courses, three were courses scheduled to transition to reuse water during the study period and three were long term users of reuse water. Salinity [electrical conductivity (EC)], NO – 3-N, PO4-P, pH, algal chlorophyll concentration, clarity, temperature, oxygen, and all major cations and anions were analyzed on a monthly basis. A selected fairway on each course was equipped with water meters to assess irrigation volumes on a bimonthly basis. Estimates of salt and NO – 3-N loading on fairways were made by weighting irrigation volumes with concentrations of salt (assuming 700 mg·L–1 per dS·m–1) and NO – 3-N measured in the irrigation ponds. Pond spectral reflectance measurements were obtained on a single monitoring day and correlated with water quality parameters. EC, temperature, NO – 3-N, PO4-P, algal chlorophyll concentration and clarity all demonstrated significant changes in all irrigation ponds that transitioned to reuse water (p < 0.05). Multiple regression analysis revealed that as much as 75% of the variability in pH in some irrigation ponds could be accounted for based on water quality parameters measured, with higher R2 values associated with elevated HCO– 3 concentrations. Spectral reflectance (individual wave bands and spectral indices) was shown to be correlated with pH, clarity and algal chlorophyll concentration (R 2 = 0.66** to 0.82***) with a well defined threshold relationship between clarity and the spectral index R705/R670. Average yearly NO – 3-N loads on fairways averaged 8.5 kg·ha–1·yr–1 on fresh water courses, 86.5 kg·ha–1·yr–1 on transition courses and 209.8 kg·ha–1·yr–1 on long term reuse courses (all significantly different at p = 0.05). Average yearly salt loads on fairways averaged 11,959 kg·ha–1·yr–1 on fresh water courses, 14,675 kg·ha–1·yr–1 on transition courses and 27,445 kg·ha–1·yr–1 on long term reuse courses (long term significantly different at p = 0.05). Such results indicate that significant attention must be given to irrigation strategies used on reuse irrigated golf courses to properly manage for higher nitrogen and salt loads.