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- Author or Editor: A. Abdul-Baki x
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Selected breeding lines and cultivars of tomatoes (Lycopersicon esculentrum Mill.) were evaluated for heat tolerance in the greenhouse (39°C day and 28°C night) and field using flowering, fruit-set, yield, fruit quality, and seed production as criteria. Under high temperature, heat tolerant lines performed better than the other two groups in all evaluation criteria except for seed production. The opposite was found under normal field conditions where heat sensitive commercial cultivars outyielded the heat tolerant lines and cultivars. Production of viable seeds under high temperature was severely reduced regardless of the heat tolerance level exhibited by the line or cultivar. Some of the heat tolerant lines could provide valuable sources of plant material for physiological studies to establish the molecular basis of heat tolerance and also could provide excellent germplasm sources for breeding heat tolerant tomato cultivars.
Abstract
It is beyond the purpose of this presentation to review all the definitions for the term “vigor” as applied to seeds. So far, no one definition has been accepted, and perhaps it is not yet time to settle on one definition until we know more about the subject.
Growth analysis was used to document growth responses of staked, fresh-market tomatoes (Lycopersicon esculentum Mill.) to black polyethylene or hairy vetch (Vicia villosa Roth) mulches. Leaf area and dry mass of vegetation and fruit were measured weekly during two growing seasons. Growth was better early in the season but worse later in the season for plants grown with black polyethylene than with hairy vetch mulch. Unit leaf rate (rate of growth per unit leaf area) of fruit was higher with black polyethylene than with hairy vetch, whereas the reverse was true of vegetation. This relationship led to a higher leaf area ratio and leaf area duration of plants grown with hairy vetch than with black polyethylene. Consequently, tomatoes grown with black polyethylene produced higher early yield because of increased partitioning to fruit. However, tomatoes grown with hairy vetch eventually outgrew and outyielded those grown with black polyethylene because of increased partitioning to leaf area.
A 3-year study was conducted at the Beltsville Agricultural Research Center, Beltsville, Md., to evaluate plant stand, growth, and yield of snap bean (Phaseolus vulgaris L.) cultivars Carlo and Matador grown with conventional tillage (CT) or with no-tillage hairy vetch (Vicia villosa Roth) (HV) mulch. Plant stand and dry mass of both cultivars in CT were similar to those in no-till HV. However, leaf area and yield with no-till HV were significantly higher than those with CT.
Stand, plant growth, and yield were determined on `Matador' and `Carlos' snap beans (Phaseolus vulgaris L.) that were planted as a summer crop in a 3-year study using conventional tillage (CT) and no-till hairy vetch (Vicia villosa L. Roth) mulch (HV) systems. The CT plots received (kg·ha–1) 67 N as ammonium nitrate at preplanting and both CT and HV plots received (kg·ha–1) 17N–34P–17K with the planter. Stand differences between CT and HV were not significant. Average yields in CT and HV over a 3-year period were 13.3 and 19.8 t·ha–1, respectively. Average plant dry mass 2 days before harvest was not significantly different between CT and HV. Leaf area per plant 2 days before harvest was 1992 and 3092 cm2 in CT and HV, respectively. Higher yield in the HV mulch system, as compared to CT, can be attributed to larger leaf area per plant, higher soil organic matter and water-holding capacity, and less soil compaction in the HV plots.
Hairy vetch (Vicia villosa Roth), crimson clover (Trifolium incarnatum L.), and rye (Secale cereale L.) and mixtures of rye with hairy vetch and/or crimson clover were compared for no-tillage production of staked, fresh-market tomatoes (Lycopersicon esculentum Mill.) on raised beds. All cover crops were evaluated both with or without a postemergence application of metribuzin for weed control. Biomass of cover crop mixtures were higher than that of the hairy vetch monocrop. Cover crop nitrogen content varied little among legume monocrops and all mixtures but was lower in the rye monocrop. The C:N ratio of legume monocrops and all mixtures was <30 but that of the rye monocrop was >50, suggesting that nitrogen immobilization probably occurred only in the rye monocrop. Marketable fruit yield was similar in the legume monocrops and all mixtures but was lower in the rye monocrop when weeds were controlled by metribuzin. When no herbicide was applied, cover crop mixtures reduced weed emergence and biomass compared to the legume monocrops. Despite weed suppression by cover crop mixtures, tomatoes grown in the mixtures without herbicide yielded lower than the corresponding treatments with herbicide in 2 of 3 years. Chemical name used: [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one](metribuzin).
Heat-tolerant and -sensitive Lycopersicon esculentum Mill. and L. pimpinellifolium (Jusl.) Mill. genotypes were grown in the greenhouse under optimum- (27/23C, day/night) and high-temperature (35/23C) stress regimes. Heat tolerance levels in the genotypes were established by determining percent fruit set at high and optimum temperatures. Under optimum temperature, fruit set ranged from 41% to 84% and from 45% to 91% in the heat-sensitive and heat-tolerant genotypes, respectively. Under high temperature, no fruit set in the most heat-sensitive genotypes. Fruit set in the heat-tolerant genotypes ranged from 45% to 65%. In vitro germination and tube growth of pollen taken from genotypes grown under optimum temperature conditions were determined before and after subjecting the pollen to 45C for 1, 2, and 4 hours. The response of pollen to heat treatments was genotype dependent and not a general predictor of fruit set under high-temperature stress.
Nitrogen requirements by fresh-market field tomatoes (Lycopersicon esculentum Mill.) were determined on plants grown in a hairy vetch mulch (HVM) or in black polyethylene mulch (BPM). Nitrogen treatments were 0, 56, 112, and 168 kg/ha delivered weekly through the trickle system. Yields in BPM increased significantly with higher applications of nitrogen from 54 to 91 tons/ha and chlorophyll content of fully expanded leaves increased from 7.8 to 11.3 OD664 per 100 mg fresh weight. In contrast, neither yield nor chlorophyll content of leaves increased significantly by adding nitrogen. The 0 nitrogen treatment in HVM yielded 89 ton/ha and chlorophyll content was 13.5 OD664 making it equivalent to those in BPM that had received 168 kg nitrogen/ha. The results suggest that hairy vetch can provide all the nitrogen required by the subsequent tomato crop and produces high yields and vigorous plants.
Hairy vetch, subterranean clover, polyethylene black mulch (PBM), and Horto paper were evaluated in field-grown fresh market production of tomatoes (Lycopersicon esculentum Mill), cv `Sunny'. Plant mulches were grown in beds in the fall, mowed immediately before planting, and the tomato seedlings were planted without tillage in a low input system. Yields (t.ha-1) for hairy vetch, subterranean clover, PBM, Horto paper, and no mulch were 72.1, 46.6, 59.9, 54.0, and 29.8, respectively. Although the tomato plants grown under plant mulches received 50% of the recommended fertilizer application, they produced more vigorous plants than those in other treatments. Plant mulches were effective in controlling growth of weeds and infestation by Colorado potato beetle.
Hairy vetch, crimson clover, and rye, separately or in combination, were grown in the fall as cover crops and mowed in the spring to form an organic mulch in a no-tillage sustainable agricultural system for production of fresh-market tomatoes (Lycopersicon esculentum Mill, cv `Sunny'). Fruiting earliness, yield, and size were compared between the organic mulch treatments and those under bare soil, paper and black polyethylene mulches. Fruiting was about 9-10 days earlier under black polyethylene mulch than all other treatments. Total marketable yields (t·ha-1) under the mulch treatments were: hairy vetch, 85; hairy vetch plus rye, 69; crimson clover, 66; black polyethylene, 44; bare soil, 36; and Horto paper, 30. Average fruit size was significantly larger in all organic mulch treatments than in bare soil, Horto paper, and black polyethylene mulches. Early growth of tomato plants was highest with plastic but subsequent growth was highest with hairy vetch. Superior vigor with hairy vetch was probably the result of higher nitrogen concentration of vetch residue relative to the other cover crops.