Two cultivars of greenhouse tomato (Lycopersicon esculentum Mill.) were grown with ambient or 1000 μl CO2/liter during Jan.-June 1987 and 1988. In both years, CO2-enrichment increased foliar deformation and foliar starch, but during the season, foliar starch levels decreased while deformation increased. `Laura' had more deformation, while `Michigan-Ohio' had higher foliar starch concentration. During an entire season, there was no significant relationship between foliar starch concentration and deformation severity. Foliar C exchange rates in the lower canopy were not affected by severity of deformation. Data from these experiments do not support the hypothesis that excess foliar starch is responsible for foliar deformation at elevated CO2.
K.E. Tripp, M.M. Peet, D.H. Willits, and D.M. Pharr
A. Liptay and S. Nicholls
Tomato transplant (Lycopersicon esculentum Mill.) root growth in the field was directly related to N level supplied to the transplants as seedlings in the greenhouse. Root growth in the field increased exponentially when N was applied at 50 to 350 mg·liter-1. Transplant growth in multicelled trays increased in a sigmoidal fashion with N, up to 200 mg-liter'. The optimal N range for maximum survival, growth, and early yield in the field was from 100 to 200 mg-liter'. Strength of the seedling stem increased with N level curvilinearly. Seedling survival in the field was highly correlated with seedling stem strength.
Angela R. Davis, Amnon Levi, Sungil Kim, Stephen R. King, and Alvaro Hernandez
RNA isolation from ripe fruit can be complicated by high concentrations of sugar and water. These sugars interfere with RNA extraction often resulting in low RNA quality and quantities, and high water concentrations dilute the RNA, making isolation difficult. We report a simple but novel method by which the majority of the excess sugar and water in mature fruit of tomato (Lycopersicon esculentum Mill.), watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai], and muskmelon (Cucumis melo L.) can be easily removed from tissue before RNA extraction. This method produced quality RNA in a shorter time than the currently accepted method for fruit tissue RNA isolation and does not require liquid nitrogen or a freeze dryer.
G. Préstamo and P. Manzano
The various isozymes of peroxidase of a range of vegetables and kiwifruit were compared using sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by specific activity staining. Peroxidase isozymes were determined in potato (Solanum tuberosum L.), carrot (Daucus carota L.), tomato (Lycopersicon esculentum Mill.), kiwifruit [Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson], cauliflower [Brassica oleracea (Botrytis group)], green beans (Phaseolus vulgaris L.), and horseradish (Armoracia rusticana Gaertn, Mey Scherb.). There was only one isozyme in cauliflower (70 kDa), two in kiwifruit (45-43 kDa), and a range of isozymes (120-36 kDa) in horseradish. Ascorbic acid inhibited peroxidase activity in the extracts.
V. Kagan-Zur, D. Yaron-Miron, and Y. Mizrahi
A spontaneous tomato (Lycopersicon esculentum Mill.) triploid was studied with a view to its commercialization. Fruits induced by auxin contained 50% more DNA and 30% more protein than their diploid counterpart. The fruits were 50% larger than those of the diploid counterpart and were juicy but seedless. All fruit quality characteristics checked (polygalacturonase activity, reducing sugars content, electrical conductivity, pH, titratable acidity, pigment content, and shelf life) were comparable to the diploid except for ethylene evolution rate, which was lower than that of the diploid counterpart, and flavor, which was superior. The line seems suitable for agricultural cultivation.
Charles S. Vavrina, Stephen M. Olson, Phyllis R. Gilreath, and Mary L. Lamberts
`Agriset', `All Star', and `Colonial' tomato (Lycopersicon esculentum Mill.) transplants set to a depth of the first true leaf and `Cobia' transplants set to a depth of the cotyledon leaves yielded more fruit at first harvest than plants set to the top of the rootball (root–shoot interface). The increase in fruit count was predominantly in the extra-large category. More red fruit at first harvest suggested that deeper planting hastens tomato maturity. The impact of planting depth diminished with successive harvests, indicating the response to be primarily a first-harvest phenomenon in tomato.
Stephen Reiners and Peter J. Nitzsche
`Pilgrim' tomatoes (Lycopersicon esculentum) grown under slitted clear polyethylene or spunbonded polypropylene rowcovers were compared to those with no protection for the effect on yield. Both covers significantly increased early yield in terms of fruit numbers and weight, but no differences were observed in total yields. In addition, no difference was observed in yield between two tomato transplant sizes- 4- to 5-leaf stage and 6- to 7-leaf stage---grown in the same-sized containers. The results from this study indicate that early tomato yield may be enhanced with the use of rowcovers.
D.J. Schuster, T.F. Mueller, J.B. Kring, and J.F. Price
A new disorder of fruit has been observed on tomato (Lycopersicon esculentum Mill.) in Florida. The disorder, termed irregular ripening, was associated with field populations of the sweetpotato whitefly, Bemisia tabaci (Gennadius) and is characterized by incomplete ripening of longitudinal sections of fruit. An increase in internal white tissue also was associated with whitefly populations. In field cage studies, fruit on tomato plants not infested with the sweetpotato whitefly exhibited slight or no irregular ripening, whereas fruit from infested plants did. Fruit from plants on which a whitefly infestation had been controlled before the appearance of external symptoms exhibited reduced symptoms compared to fruit from plants on which an infestation was uncontrolled.
Martha A. Mutschler, David W. Wolfe, Edward D. Cobb, and Kenneth S. Yourstone
Fruit of tomato (Lycopersicon esculentum Mill.) hybrids heterozygous for the alc ripening mutation stored on average 60% (3.6 days) longer at 20C than that of their normal-ripening parents. There were no detrimental effects of the alc heterozygous condition on fruit color, firmness, or size. The background into which alc was introduced also affected fruit quality and shelf life. These results indicate hybrids heterozygous for the alc ripening mutant can produce commercially acceptable fruit with significantly longer shelf life than their normal-ripening parents.
Aref A. Abdul-Baki, S. A. Haroon, and R. N. Huettel
Susceptibility of tomato (Lycopersicon esculentum Mill) genotpyes to the root-knot nematode Meloydogyne incognita and to heat stress can be evaluated in a single labor- and time-saving operation using a nondestructive in vitro excised root technique. Seeds are sterilized and germinated for 2 days on 1% water agar. Five-mm root sections are grown at 28 and 35 C for 30 days on Gamborg-B medium with and without nematode inoculum. Evaluation criteria include fresh and dry weight and the appearance of juveniles, adults, gulls, and egg masses. Evidence will be presented on the breakdown of resistance to M. incognita under high temperature stress.