Botrytis cinerea and rachis browning as a result of desiccation are the two main factors that reduce table grape postharvest quality ( Nelson, 1985 ). The means for preventing decay during storage is the use of sulfur dioxide (SO 2 ), which was first tried
Abstract
‘Shasta’ chrysanthemum (Chrysanthemum morifolium Ramat) showed less SO2-induced leaf necrosis than ‘Hurricane’. The growth retardant a-cyclopropyl-a-(4-methoxy-phenyl)-5-pyrimidine methanol (ancymidol) at 0.16 and 0.48 mg ai/2.5 cm pot reduced SO2 damage on both cultivars. There was positive correlation between stomatal activity (water diffusion resistance) and degree of leaf necrosis from SO2.
Abstract
The capacity of rhododendron (Rhododendron catawbiense Michx., cv. Nova Zembla) and firethorn (Pyracantha coccinea M. J. Roem. var. Lalandii (Duren) Dipp.) to change ambient SO2 levels in a closed fumigation system was studied. P. coccinea removed greater quantities of SO2 at faster rates than R. catawbiense. Differences in leaf surface characteristics between the 2 species suggest that at least part of the SO2 uptake mechanism may involve a surface-mediated response to the pollutant.
Abstract
Spinach (Spinacia oleracea L.) was exposed intermittently to NO2 and SO2 (2 hours/week; 0.8 or 1.5 ppm) in a simultaneous or sequential fashion over the 42-day growth period. Nighttime simultaneous exposure to NO2 and SO2 reduced growth and altered assimilate partitioning to the root. The relative growth rate of total plant and root was reduced significantly below controls early in the growth period. In contrast, neither daytime exposure to the pollutant mixture nor sequential exposure to the 2 pollutants affected growth.
Abstract
Seeds of Zamia furfuracea Ait. (cardboard plant) were treated following removal of the sarcotesta (fleshy seed coat) with concentrated H2SO4 and 1000 ppm GA3 in a 4 × 4 factorial combination. The highest total germination of 82.2% in an average time of 74.5 days (germination value = 0.070) was achieved when seeds were exposed to H2SO4 for 15 minutes. Average number of days to germination was reduced to 37.7 when 30 minutes of H2SO4 treatment was followed by 24-hour GA3 soak without significantly affecting percent germination (germination value = 0.103). Interactions of H2SO4 and GA3 are explained by the effect of H2SO4 on sclerotesta (stony seed coat) thickness and the effect of GA3 on the accelerated development of an immature embryo.
Abstract
Soil moisture stress (SMS) and abscisic acid (ABA) pretreatment had a marked effect in modifying SO2 sensitivity in 2 cultivars of poinsettia (Euphorbia pulcherrima Willd. ex Klotzch.) ‘Ruff and Reddy’ and ‘Rudolph’. Plants grown in 10-cm plastic pots in the greenhouse and exposed to SMS by withholding water for 2.5 days prior to SO2 fumigation in the growth chamber (4 hr at 3 μ1·liter−1) showed greatly reduced SO2 injury; both cultivars were protected similarly. SMS treatment also greatly decreased stomatal conductance and transpiration rate of the leaves. ‘Ruff and Reddy’ plants pretreated with ABA (200 mg·liter−1 of the racemic mixture) 4 hr prior to SO2 fumigation were injured less by SO2 than ‘Rudolph’ and had correspondingly lower stomatal conductance and transpiration rate. ‘Rudolph’ plants pretreated with ABA did not show significantly less SO2 injury, even though stomatal conductance and transpiration rate were lower than controls after ABA pretreatment. These findings demonstrate the importance of moisture stress preconditioning in modifying sensitivity of poinsettia plants to SO2 and suggest a protective role for ABA in certain cultivars.
Abstract
Potted vines of ‘Cabernet Sauvignon’ and ‘White Riesling’ grapes (Vitis vinifera L.) and potted ‘Bartlett’ pear (Pyrus communis L.) and ‘Hartley’ English walnut trees (Juglans regia L.) were grown in greenhouses for 2 seasons and fumigated with ambient levels of H2S, treble ambient H2S, and amounts of SO2 equivalent to the treble levels of H2S. No foliar symptoms or deleterious effects on growth or fruiting were observed which could be ascribed to the treatments.
Abstract
Lettuce (Lactuca sativa L. cv. Grand Rapids) and radish (Raphanus sativus L. cv. Cherry Belle) plants growing at baseline environmental conditions were exposed to charcoal-filtered air, 0.40 ppm (v/v) ozone, and 0.80 ppm sulfur dioxide alone or in combination for 6 hours at 14 days from seeding. Analysis of covariance was used to account for significant within-treatment variation in plant growth. Covariates used were: planar leaf area (PLA) at 14 days for leaf area, fresh weight, and dry weight at harvest; plastochron index (PI) at 14 days for PI at harvest; and hypocotyl diameter for hypocotyl weights of radish roots at harvest. The covariates reduced the variability (standard geometric errors) of the response variables and increased the precision of statistical tests substantially for lettuce but much less for radish. For lettuce, the effect of the gas mixture on plant growth and foliar injury was less severe than that of the single gases. Radish plants, in contrast, exhibited no response to SO2 and the effects of O3 and the mixture on foliar injury and plant growth were similar.
Abstract
Flowering plants of 5 cultivars of petunia (Petunia hybrida Vilm.), exposed to 2.8 ppm SO2 (16 hours) under controlled environmental conditions, exhibited variation in SO2 sensitivity based on the degree of water-soaked necrotic leaf lesions. The range of SO2 absorption rates was ± 14% of the mean for the 5 cultivars; however, there was a 2-fold difference in sensitivity among the cultivars, indicating that variation in SO2 absorption plays only a limited role in determining the genetic differences involved in the reaction of petunia to SO2. Detached leaves from all cultivars were equally sensitive to a 10 mM Na2SO3 solution. The injury response of leaf discs to Na2SO3 solutions was monitored by chlorophyll extracts. Although the cultivars varied in sensitivity, the ranking differed from that observed for whole plants to SO2. Callus cultures grown on Murashige and Skoog (MS) medium + naphthaleneacetic acid (NAA) at 2.0 mg/liter + ben-zylamino purine (BA) at 0.5 mg/liter were treated with Na2SO3. Their viability, when evaluated by triphenyl tetrazolium chloride (TTC), yielded a sensitivity ranking of the same cultivars which differed from that obtained with both leaf discs and whole plants. No differences in Na2SO3 sensitivity were observed for callus cultures of the cultivars cultured on MS + 1.0 mg/liter 2,4-dichlorophenoxyacetic acid (2,4-D). The dissimilar injury responses to SO3 =/HSO3 − in different tests on explants of the same cultivars indicate that at each level of plant organization sensitivity to Na2SO3 is determined by different morphological and physiological factors from those which specify whole plant reaction to SO2.
Abstract
Greenhouse experiments using seedling pecan trees [Carya illinoensis (Wan-genh.) C. Koch] compared rates and repeated applications of K2SO4, K2SO4 vs. KNO3, and Ν adjuvants in combination with K2SO4 or KNO3. Leaf and stem Κ concentrations increased linearly with rates to 87.1 g/liter K2SO4 applied 5 times at 14-day intervals. Phytotoxicity was negligible to 10.9 g/liter K2SO4. Plants receiving individual applications of KNO3 or K2SO4 at 9.8 g K/liter 2 times at 14-day intervals had 92% and 53% more Κ than the control, respectively. KNO3 at 25.3 g/liter or K2SO4 at 21.8 g/liter, in combinations with urea and/or NH4NO3 at 6.25, 12.50, and 25.00 g/liter, increased leaf Κ concentration significantly and the increase was consistently greater using KNO3 than K2SO4. Both urea and NH4NO3 applied with either KNO3 or K2SO4 increased leaf Κ concentrations. Negligible phytotoxicity occurred when urea or NH4NO3 was applied at 6.25 g/liter with K2SO4 or KNO3.