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Hanna Y. Hanna

Cultivars and growing media are important components of a successful greenhouse tomato (Solanum lycopersicum) operation. Two studies were conducted simultaneously and independently in two 30 × 96-ft greenhouses in Spring 2006 and 2007 (January–July) to assist producers in selecting appropriate cultivars and reducing production cost. The first study was conducted to evaluate yield, fruit weight, fruit quality, and shelf life of ‘Geronimo’, ‘Quest’, and ‘Trust’ tomatoes planted in perlite and pruned to three or four fruit per cluster. The second study was conducted to determine the initial cost of perlite, pine bark, and rockwool growing media and their effect on yield of ‘Quest’ pruned to three or four fruit per cluster. ‘Geronimo’ produced the highest total marketable yield and ‘Trust’ produced the lowest. ‘Trust’ produced more cull yield and lower fruit weight than ‘Geronimo’ or ‘Quest’. Pruning clusters to three fruit increased total marketable yield and fruit weight, and reduced cull yield of all cultivars. Only ‘Geronimo’ produced higher early marketable yield at four fruit per cluster. All cultivars produced higher early marketable yield in 2007 than in 2006. Tested cultivars had similar fruit content of potassium and sodium and similar concentration of soluble solids. ‘Trust’ fruit had a higher pH than the other two cultivars. About 92% of ‘Quest’ tomatoes remained marketable after storage at 67 °F for 1 week. ‘Geronimo’ and ‘Trust’ had only 83% and 78% marketable fruit, respectively, under the same conditions. Initial costs to grow greenhouse tomatoes in perlite were higher than in rockwool, and were the lowest in pine bark. Plants grown in perlite produced higher total marketable yield than plants grown in either of the other media. They produced lower cull yield than plants grown in rockwool, but produced similar cull yield to plants grown in pine bark. Pruning clusters to three fruit increased total marketable yield and fruit weight in both studies. Pruning clusters to four fruit increased cull yield in both studies regardless of planting year.

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Hanna Y. Hanna

Planting greenhouse tomatoes (Solanum lycopersicum) in the same perlite more than once without reconditioning to restore medium loose structure, desalination to remove excess salt, and disinfection to guard against pest contamination is risky, and replacing the perlite to produce every new crop is costly. Reconditioning and treating perlite with hot water at a minimum cost provides a favorable solution for both problems and saves natural resources. A study was conducted in a 30 × 96-ft greenhouse in Spring 2007, 2008, and 2009 (January–July) to evaluate three methods for perlite recycling cost, desalination efficiency, and effects on tomato yield at three or four fruit per cluster. Each recycling method consisted of two components: the reconditioning action and the hot water treatment. The three recycling methods included no stir/sift then disinfect, stir then disinfect, and sift then disinfect. Perlite recycled with the no stir/sift then disinfect method was not reconditioned before the hot water treatment. Instead, it was agitated with a nozzle mounted on a pressure washer wand during the hot water treatment. Perlite recycled with the stir then disinfect method was reconditioned first with an auger mounted on an electric drill and then treated with hot water. Perlite recycled with the sift then disinfect method was reconditioned first by sifting the perlite with a homemade apparatus and was then treated with hot water. Recycling perlite with the no stir/sift then disinfect method reduced labor input by 49% and 81% compared with the stir then disinfect and the sift then disinfect methods, respectively. The no stir/sift then disinfect method reduced recycling cost by 22% and 50% compared with the other two methods, respectively. Perlite that was not reconditioned (no stir/sift) had higher nitrate-nitrogen (NO3-N) before hot water treatment than the stirred perlite and equal NO3-N to the sifted perlite. Hot water treatment significantly reduced medium electrical conductivity, NO3-N, potassium, and sodium. Tomatoes grown in perlite recycled with any of the three methods produced similar marketable and cull yields and fruit weight. Pruning fruit to three per cluster increased marketable yield, fruit weight, and reduced cull yield. There was no significant recycling method × cluster pruning interaction for yield components, indicating that all recycling methods had similar effects on tomato yield at three or four fruit per cluster. We conclude that the no stir/sift then disinfect method is less time consuming, more economical, and has no negative impact on yield. Tomatoes grown with three fruit per cluster in perlite recycled with any of the three methods produced greater marketable yield, less cull yield, and heavier fruit than tomatoes grown with four fruit per cluster.

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Hanna Y. Hanna

Growing grafted hybrid tomato (Solanum lycopersicum) cultivars in greenhouse operations is gaining popularity worldwide. The costs of producing grafted plants remain a deterrent to the smaller producer. After removing plant tops to use as scions for grafting tomato plants, the stumps that have well-developed root systems and cotyledon leaves are usually discarded with the root media and containers. If productive plants can be produced from sprouts on the stumps, they can be used as non-grafted hybrids at the same farm or sold to other growers for income to defray part of the grafting costs. A 2-year greenhouse study examined the effects of three propagation methods and three tomato cultivars on plant yield and related traits. Seedling, grafted, and stump sprout plants of the hybrid cultivars Geronimo, Quest, and Starbuck were used in this study. Plants grafted on ‘Maxifort’ rootstock had greater stem diameter (P < 0.0001) below the first and third clusters than the seedling or stump sprout plants. The seedling plants had greater stem diameter than stump sprout plants below both clusters. During the first 3 weeks of harvest, seedling plants produced greater yields (P < 0.0001) than grafted or stump sprout plants and the differences were cultivar related. ‘Quest’ was the only cultivar that produced similar yields (2.8 vs. 2.3 lb) as a seedling or a grafted plant during the first 3 weeks of harvest. Tomato plants propagated by all three methods produced similar yields and fruit weight in the remaining 16 weeks of harvest. Cultivars had no significant effect on yield during the first 3 weeks of harvest (P > 0.05), but their yields were significantly different during the remaining 16 weeks of harvest (P < 0.0001). The apparent reason for yield advantages of the seedling plants during the first 3 weeks of harvest was the uninterrupted growth during the seedling stage. Propagation method had no specific influence on fruit quality attributes. On the bases of this study, producing productive tomato plants from stump sprouts is a feasible cultural technique that can reduce losses associated with plants used in grafting. It also allows the repeated use of the soilless media and the seedling containers. The produced plants can generate substantial income for businesses that graft a significant number of tomato seedlings. For this cultural method to work, grafting should be timed to allow the stump sprout plants to grow for at least 5 weeks before planting in the grow bags. This practice is normally followed in producing transplants from seeds.

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H.Y. Hanna

In the southern United States, the polyethylene-mulched and drip-irrigated beds remaining after the last harvest of fresh-market tomatoes (Lycopersicon esculentum) offer the potential for producing a cucumber (Cucumis sativus) crop to increase grower profit. A 2-year study of double-cropping cucumbers with `Celebrity' (nematode-resistant) and `Heatwave' (nematode-susceptible) tomato cultivars was conducted at the Red River Research Station in northwestern Louisiana to assess the benefits of this system and to determine how soon cucumbers should be planted following the termination of the tomato crop. Results indicated that cucumbers planted after `Celebrity' produced significantly greater premium and total yields per acre than did cucumbers planted after `Heatwave'. Plant fresh weight of cucumbers was greater and the percentage of galled roots was smaller when planted after `Celebrity' than when planted after `Heatwave'. Planting dates had significant effects on cucumber yield. Cucumbers planted in early July, immediately after the termination of the tomato crop produced the highest yield. Cucumbers planted in early August, 1 month after terminating the tomato crop produced an intermediate yield, and cucumbers planted in September, 2 months after the termination of the tomato crop, produced the lowest yield. A gradual decline of plant fresh weight and a gradual increase of galled-root percentage resulted from delaying cucumber planting beyond the July month. Year of planting had no significant effect on cucumber productivity, but it did influence plant fresh weight and the percentage of galled roots significantly. Average minimum temperature in September was lower than the minimum safe temperature for growing cucumbers. The combined effect of higher temperature and lower percentage of galled roots may have contributed to the increased yield of cucumbers planted in July.

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H.Y. Hanna

A study was conducted to determine if air blowers would be less time consuming, more economical, and as effective as hand-held electric vibrators to pollinate two greenhouse tomato (Lycopersicon esculentum) cultivars. Vibrator-pollinated plants of each cultivar produced greater marketable yield than did blower-pollinated plants. Within cultivars, marketable yield was greater and yields of culls were lower with vibrator-pollinated plants. Fruit weight and diameter and the number of seeds per fruit were greater in vibrator-pollinated plants. Marketable yield of `Trust' was greater and cull yield was lower than that of `Caruso' in 1996. However, marketable yield of `Caruso' was greater than that of `Trust' and cull yield was about the same in 1997. Interactions between pollinating tools and cultivar were not significant except for fruit weight in 1997. The time needed to pollinate 640 plants for 13 weeks was 7.13 and 11.75 person-hours using the air blower and the electric vibrator, respectively. Labor cost for pollination was $49.92 for the air blower and $82.25 for the vibrator. Yield loss using the air blower for pollination was not offset by the savings in operating costs.

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H.Y. Hanna

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).

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H.Y. Hanna

A study was conducted to determine if raising tomatoes (Lycopersicon esculentum) in cleaned and disinfected used perlite would be more economical than new perlite and have no negative impact on yield. Cleaning and disinfecting used perlite for recycling saved 56% of the cost to replace the media and reduced salt content to the optimum level recommended for raising container grown plants. Disinfecting used perlite with hot water raised media temperatures above limits necessary to kill several fungi and nematodes. Tomatoes planted in recycled perlite produced greater marketable yield and heavier fruit than those planted in new perlite. Season and year of planting also have significant effects on yield. Used perlite can be cleaned and disinfected as needed and recycled for many years because it is not organic in nature and physically and chemically stable.

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H.Y. Hanna

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.

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H.Y. Hanna

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.

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H.Y. Hanna

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.