Search Results
Abstract
‘Tropic’ and ‘Walter’ tomatoes (Lycopersicon esculentum, Mill.) were grown in central Alabama on a Lucedale fine sandy loam soil (Rhodic Paleudult) with uniform 0- to 15-cm surface soil pH of about 6.0 and subsoil pH ranging from 4.4 to 6.2. Depth and amount of soil water extraction and plant heights increased as subsoil pH increased. Marketable tomato yields were influenced by subsoil pH, with maximum yields occurring at pH 5.6 to 5.8. Marketable yields ranged from 10,400 to 55,500 kg/ha for ‘Tropic’ and from 14,000 to 39,400 kg/ha for ‘Walter’. Yield of large size fruit of ‘Tropic’ was greater above pH 5.0 than below pH 5.0. Fruit size distribution for ‘Walter’ was not affected by subsoil pH.
Abstract
Field studies were conducted to determine the response of snap beans (Phaseolus vulgaris L.) and cucumbers (Cucumis sativus L.) to no, intermediate, and high irrigation with 0, 65, 100, and 135 kg N/ha on beans and 56 and 112 kg N/ha on cucumbers. Intermediate irrigation increased marketable yields, but high irrigation did not. Average snap bean yields for the 3-year period by soil water regimes were 5,800, 7,000, and 6,800 kg/ha, and for cucumbers were 32,200, 35,400, and 33,000 kg/ha for no, intermediate, and high irrigation, respectively. Applied N increased yields, with the 3-year average snap bean yields being 4,600, 6,600, 7,200 and 7,700 kg/ha for 0, 65, 100 and 135 kg/ha rates, respectively, and cucumber yields being 31,900 and 35,100 kg/ha for 56 and 112 kg/ha, respectively. There was a greater response to N fertilizer on the spring crop than on the fall crop.
Abstract
Ethylene production of 470 ‘Hi-Early Red Delicious’ apples harvested from primary, secondary, tertiary, etc., branches of 4 uniform trees of Malus domestica Borkh. was measured to determine pattern of ripening in relation to fruit position on the tree. Considerable variation was noted between and within branches. Some fruits showed surprisingly high ethylene (about 200 ppm at 155 days and up to 500 ppm at 160 days after full bloom) while others measured less than 5 ppm. Regression analysis revealed a linear trend between primary branches from base to apex of the tree. Delayed ethylene production of fruits below terminal shoots suggests ripening regulators in shoot tissue are interacting to delay ethylene synthesis.
Peach-to-nectarine mutations are associated with broad pleiotropic effects. The present study addresses the heritability of nectarine-specific effects in three hybrid families. A comparison of peach and nectarine siblings showed that nectarine fruit were smaller (less fresh weight), rounder, darker, redder, and had higher levels of sugars and organic acids. These heritable characteristics are similar to effects of spontaneous peach-to-nectarine mutations described previously.
Abstract
A method is described whereby relative humidity is reduced in the atmosphere of agar-solidified tissue cultures. Plantlets of chrysanthemum (Chrysanthemum X morifolium Ramat.) cultured under low humidity exhibited a high mortality rate and those that survived were smaller and had few roots. Severe retardation of stomatal development occurred under reduced humidity and mature stomata had considerably narrower apertures than did plantlets grown at about 100% relative humidity. Plantlets of cauliflower (Brassica oleracea L. Botrytis group) cultured under reduced humidity also exhibited reduced growth but, in addition, developed large quantities of surface wax and had lower rates of water loss. The results are discussed in relation to the potential uses of the technique for acclimatization of plantlets prior to transfer to soil.
Increased interest has been demonstrated in the production and marketing of thornless blackberries. Once blackberries are harvested, the length of time they can be stored at low temperatures above freezing is limited by initiation of fungal spoilage and rapid loss of market quality. The objective of this study was to assess effects of low dose γ-irradiation and modified atmosphere packaging on market quality retention of thornless blackberries as evaluated by Hunter color values, Instron shear rates, TSS, pH, and microbial growth over 96 h. Blackberries were irradiated at ambient temperatures using a Nordion Gammacell Model 220 (dose rate =11.0 Grays/min) delivering a 0.3 kGy dose to the tissue. Both control and irradiated samples were placed in packaged and nonpackaged groups, stored over 96 h (4°C), taken for analysis at 24 hr intervals. An additional treatment included packaged controls containing C2H4 absorbant. Following 72 h storage, packaged samples were stored in air to determine subsequent benefit. CO2 and O2 concentrations inside packages were 7.5% and 11.6%. By 72 hr, yeast and mold counts were lower in irradiated, packaged samples, but a significant increase was observed following placement of samples in air.
Abstract
Field studies were conducted on an Orangeburg sandy loam soil (Typic Paleudults) in central Alabama to determine the effects of tillage methods (complete, strip, and no-tillage), nitrogen rates (100 and 200 kg/ha), and rye (Secale cereale) cover crop on growth and yield of tomatoes (Lycopersicon esculentum Mill.). Marketable tomato yields tended to decrease as amount of tillage decreased. The 3-year average yields for complete-tillage, strip-tillage, and no-tillage treatments were 29.9, 27.0, and 26.0 MT/ha, respectively. There was no consistent effect from N-rate on marketable yields. Average yields from the lower N-rate were greater than the higher N-rate in the two driest years and were similar or higher from the higher N-rate in the year of more average rainfall. Marketable yields tended to be greater on no-rye plots than on rye plots, with yields averaging 2.2 MT/ha higher for no-rye plots.
Abstract
Field studies were conducted on Plinthic and Typic Paleudult soils in central Alabama to determine the response of tomatoes (Lycopersicon esculentum Mill), to furrow, sprinkle, and trickle irrigation with and without in-row chiseling. Irrigation by all methods and in-row chiseling increased plant heights which ranged from 70 to 120 cm at first harvest. Marketable tomato yields were influenced more by irrigation (37% increase) than by chiseling (8% increase). Yields averaged 36.7 metric tons/ha with no irrigation and 50.1 metric tons/ha with irrigation. No difference was found between irrigation methods. Amounts of irrigation water applied per season averaged 34.5 cm for furrow, 37.4 cm for sprinkle, and 16.0 cm for trickle. In-row chiseling increased yields an average of 3.7 metric tons/ha, but was significant in only 1 of 3 years.
This report presents preliminary data and arguments supporting the investigation and possible adoption of a low-cost method of cherry and grape tomato (Solanum lycopersicum) production. Cherry and grape tomato crops are currently grown using indeterminate or relatively large determinate plants requiring trellising and significant hand labor at harvest. In contrast, processing tomato crops are usually determinate cultivars raised without supporting systems, and they are harvested mechanically. In Summer 2009, a Mississippi trial of home garden tomato cultivars included a compact, mounding yellow-fruited cherry tomato that produced more than 2 kg of fruit per plant in the first harvest. The architecture of the plant, high yield potential, and concentrated set indicate that there is potential to grow commercial cherry and grape tomato crops in much the same way commercial processing tomatoes are grown: unsupported on bare or mulched beds, with once-over harvest. Such a system could reduce the monetary and labor costs of production of cherry and grape tomatoes. Seed companies, tomato growers, and supporting agencies should work together to further investigate the potential of this system of cherry and grape tomato production.
Demand for organically grown produce is increasing, largely due to concerns of consumers about health and nutrition. Previous studies have not shown a consistent difference of essential nutrients, such as vitamins and minerals, between organic food crops and the conventional counterparts. However, to date, little consideration has been given to phytochemicals, secondary plant metabolites with potential health-promoting properties. We first discuss factors that can infl uence the levels of phytochemicals in crops, and then we critically review the results of published studies that have compared the effects of organic and conventional production systems on phytochemical contents of fruit and vegetables. The evidence overall seems in favor of enhancement of phytochemical content in organically grown produce, but there has been little systematic study of the factors that may contribute to increased phytochemical content in organic crops. It remains to be seen whether consistent differences will be found, and the extent to which biotic and abiotic stresses, and other factors such as soil biology, contribute to those differences. Problems associated with most studies tend to weaken the validity of comparisons. Given the limitations of most published studies, needs for future research are discussed.