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- Author or Editor: Hanna Y. Hanna x
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A study was conducted in Summer 1996 and 1997 to determine the residual effects of planting nematode-resistant vs. susceptible tomato (Lycopersicon esculentum Mill.) cultivars and use of white vs. black polyethylene mulch on the growth and yield of a subsequent muskmelon (Cucumis melo L.) crop. Tomato cultivars were planted in early April and harvested in June and early July. Muskmelons were planted in late July on the same beds. Muskmelons, planted after the nematode-resistant tomato cultivar Celebrity, produced significantly greater marketable yield and more fruit per hectare in both years than did muskmelons planted after the nematode-susceptible tomato cultivar Heatwave. Plant dry weight of muskmelons was greater and the percentage of their galled roots was smaller when planted after nematode-resistant tomatoes than when planted after nematode-susceptible ones. Mulching tomatoes with black or white polyethylene had no significant effect on growth, yield, and root galling of subsequent muskmelon crops.
Studies were conducted in 1994, 1995, and 1997 to determine the effect of assisting natural wind pollination using an air blower on yield and fruit characteristics of three tomato (Lycopersicon esculentum Mill.) cultivars. Tomato plants and flowers in the air blower–assisted treatment were vigorously vibrated at midday every other day on sunny days for 4 weeks. Plants and flowers in the control treatment were exposed to ambient wind only. Early yield was significantly greater in the treated plants in 2 years, marketable and total yields for all tested cultivars were significantly greater in all years, and yields of culls were significantly lower in 2 years. Fruit weight and diameter and number of seeds per fruit were increased in all years.
Several studies were conducted to determine the effect of using tomato (Lycopersicon esculentum Mill.) plant skeletons as a support for trellised cucumbers (Cucumis sativus L.) double-cropped with tomatoes. In addition, the effect of mulch color, drip irrigation, and root-knot nematodes on subsequent cucumber yield also were examined. The presence of tomato skeletons significantly reduced the total yield (U.S. Fancy, no. 1, and no. 2), but not the premium (U.S. Fancy, no. 1) yield of cucumbers. Black polyethylene mulch used for the previous tomato crop had no undesirable effect on cucumber yield compared to the white mulch. Drip irrigated cucumber using same tomato irrigation lines significantly increased cucumber yield compared to nonirrigated cucumber. Cucumbers planted after nematode resistant tomatoes produced significantly higher yields than cucumber planted after nematode-susceptible tomatoes.
Several studies were conducted from 1988 to 1990 to determine the effect of using tomato plant skeletons as a support for trellised cucumbers double-cropped with tomatoes. In addition, the method by which tomato plants were killed before cucumbers were planted and the in-row spacing and row arrangement of cucumber plants on subsequent cucumber yield were also examined. Yields of trellised `Dasher II' cucumber (Cucumis sativus L.) plants planted in tomato (Lycopersicon esculentum Mill.) plots fumigated with metam-sodium were not significantly higher than yields from plants grown in plots where tomato plants were killed with glyphosate or paraquat. The presence of tomato skeletons significantly reduced the average total yield, but not the average premium yield, of three cucumber cultivars in 2 years of the study. Cultivar effect on yield was significant, and there was a significant cultivar × tomato skeleton interaction for yield during 1988. Spacing cucumber plants in the row in the presence of tomato skeletons significantly influenced yields. Planting cucumbers in double rows per tomato bed with tomato skeletons in between significantly increased yield in 1988, had a mixed effect in 1989, and had no effect in 1990 when compared with planting cucumbers in a single row per bed. Chemical names used: l,l' -dimethyl-4,4′-bipyridinium salts (paraquat); N -(phosphonomethyl)glycine (glyphosate); sodium N- methyldithiocarbamate (metam-sodium).
Black polyethylene mulch is preferred for producing early spring tomatoes (Lycopersicon esculentum Mill.) because of its warming effect on the soil around the roots. However, using the same mulch for double-cropping cucumbers (Cucumis sativus L.) with tomatoes is considered by some growers to be undesirable because of the belief that heat accumulation under the mulch in midsummer or early fall is detrimental to cucumber yield. Eight studies were conducted from July to September in 1994, 1995, and 1996 to determine the effects of mulching spring tomatoes with black vs. white polyethylene mulch on the growth and yield of subsequent cucumber crops. Soil temperature recorded after planting cucumbers ≈4:00 pm for 3 weeks was higher under black mulch than under white mulch. Color of the mulch did not affect leaf length, leaf width, and plant dry weight of cucumbers in six of the eight studies. Cucumbers grown on black mulch produced longer leaves in one study and wider leaves in two studies, and plant dry weight was lower in two studies. Mulch color had no significant effect on the premium or total yields of cucumbers in all but one study. Cucumbers grown on black mulch produced lower percentages of culls in two studies.
Abstract
Fruit set of 6 genotypes of tomato (Lycopersicon esculentum Mill) ranged from 50% (BL6807) to l% (L401) in the summer and from 93% (BL6807) to 78% (L401) in the spring. Flower drop was significantly higher in the summer for each cultivar, except for BL 6807 where there was no difference. All genotypes had significantly more underdeveloped ovaries in the summer and generally less normal pollen, smaller fruit, and less seed per fruit. Although these variables were related to low fruit set at high temperatures, they were not primarily responsible for this character.
Abstract
Seven tomato genotypes (Lycopersicon esculentum Mill) were crossed in all except reciprocal combinations in a diallel test for heat tolerance. S6916 had the highest general combining ability (GCA) value for heat tolerance, indicating that it transmitted good fruit setting abilty at high temperatures to its progeny. BL6807 had the second highest GCA value for fruit set but also transmitted underdeveloped ovaries. L401 had the lowest GCA value for fruit set. Additive gene action was more important than nonadditive effects for fruit set, flower drop, and underdeveloped ovaries at high temperatures.
Seaweed extract has been reported to have various beneficial effects on many crops. A study was conducted in 1989 and 1990 to evaluate the effects of Response 9-9-7, a seaweed extract fortified with NPK, on yield of staked tomatoes and cucumbers. Plants were sprayed to the runoff weekly, biweekly, every 3 weeks and every 4 weeks with 1:500, 1:250, 1:150 and 1:125 v/v Response/water respectively. Results indicate that spring tomatoes sprayed with Response 9-9-7 at all rates outyielded the check which was sprayed with plain water. However, the only significant difference was obtained when tomatoes were sprayed with 1:150 Response/water in 1989 and 1:500 in 1990. Response/water at 1:500 rate significantly increased the quality and marketable yield of cucumber in both years. Response 9-9-7 had no effect on yield of tomatoes grown in the summer under heat stress.
Apple scab, caused by Venturia inaequalis (Cke.) Wint., is the most serious disease of apple trees. Resistance to V. inaequalis, derived from the small-fruited species Malus floribunda 821, is determined by a major dominant gene Vf. Our major objective is to identify RAPD markers linked to the Vf gene. The approach in this paper is based on the introgression of the Vf gene from M. floribunda into commercial cultivars. Almost 200 random sequence decamer-primers have been used to screen a pair of bulked samples and the donor parent M. floribunda clone 821 for markers linked to the Vf gene conferring resistance to apple scab. A single primer has been identified which generated a PCR fragment, OPK16/1300, from the donor parent M. floribunda clone 821 and the scab-resistant selections/cultivars bulk, but not from the scab-susceptible recurrent parent bulk. Co-segregation analysis using a segregating apple progeny and polymorphism analysis of individual scab-resistant Coop selections/cultivars have confirmed that this marker is linked to the scab-resistance gene Vf. OPK16/1300 has since been cloned and sequenced. Sequence-specific primers of 25 oligonucleotides based on the marker have been synthesized and used to screen further M. floribunda clone 821, scab-susceptible apple cultivars, scab-resistant apple cultivars, and scab-resistant Coop selections. The sequence-specific primers have identified polymorphisms of OPK16/1300 based on the presence or absence of a single band.