Egbert Ralph, Research Scientist

Characteristics of New Varieties of Tomato

Between January 1997 and August 1998 a series of trials were conducted to evaluate the adaptability of over 35 varieties of tomato.  Evaluations were conducted at the National Agricultural Research Institute at Mon Repos and on farmers' fields along the coast of Guyana.

Trials were established on Onverwagt clay, which has a fine granular structure that is friable and poorly drained; pH 5.7.

Seeds were sown into seedling trays and seedlings transplanted 4-6 weeks after sowing.  Fertilization consisted of the following:

                                                     40% at flowering

                                                     30% at fruit set

              TSP -         80 kg/ha:        all at transplanting

              MOP -       120 kg/ha:        50% at transplanting

                                                      50% at flowering

Spacing used was 60cm X 40cm; approximately 41000 plants/ha.  Crops were grown in the dry season as well as the wet season.

The following describes some characteristics of five of the best performing varieties; most of the varieties so far are identified by code.

TA

This is a very short (39cm tall) determinate variety, producing small, firm, round fruits moderately sweet to taste; slight cracking may occur in mature fruits.

Fruit setting under high temperature is very good with the variety producing harvested fruits 10 days earlier than the local variety (first harvest 63 days after transplanting).  Harvesting can take place for 8 weeks with most fruits being produced between weeks 3-5 of the harvest period.  Yield per plant averages 1.5 kg with a total yield of up to 63.9 t/ha.  While fruits are small (19g), a large number of fruits are produced (79 per plant).

The variety has shown tolerance to bacterial wilt and a low incidence of bacterial soft rot.  It also shows good adaptability to dry conditions being able to produce 50% more yield than the local variety.

TB

A tall (105 cm) indeterminate variety, TB produces medium firm, plum shaped fruits that are sweet to taste; no cracking occurs in mature fruits.  Fruit set is fairly heavy with first harvest occurring 55-70 days after transplanting, depending on environmental conditions.  Harvesting can occur for up to 5 weeks, with yield as high as 62 t/ha.  Fruits are small (22g) but many are produced on each plant (72).  Mean yield per plant 1.45 kg. 

The variety shows good adaptability when grown under dry conditions and moderate susceptibility to bacterial and fusarium wilt.

TC

This is a tall (110 cm) indeterminate variety producing medium firm, round shaped fruits that are sweet to taste; the variety displays no fruit cracking.  Fruit setting is fairly heavy; first fruit set can occur 31 days after transplanting.  Harvesting lasts for a period of 7 weeks with highest yield occurring between weeks 2-5.  Yields obtained are as high as 60 t/ha.  Also a prolific producer (60 fruits/plant) fruits produced are small (24g).  Yield per plant averages 1.3 kg.

Can produce well under dry conditions.  The variety shows moderate to light resistance to bacterial and fusarium wilt.

Alafua Winner

A short determinate plant (50-60 cm tall) this variety produces small round fruits weighing about 32g.  Fruits are medium firm (moderate resistance to transportation) and show no cracking.  Fruit ripening is uniform with a high fruit set rating; fruits are medium sweet to taste.

First fruit set takes place 50 days after transplanting.  The harvest period lasts for 7 weeks with peak harvest occurring from the 2^nd - 5^th weeks of harvest.  High yield obtained per plant (1.5 kg), fruits however, half the size of local variety.  Total yield obtained as high as 74 t/ha.  Performs well under wet and dry conditions.  The variety shows tolerance to bacterial wilt and moderate susceptibility to soft rot.

Capitan

A short indeterminate plant (60 cm tall), Captain produces a medium large, round fruit weighing 68g.  Fruits are medium in firmness but displays a fair degree of cracking; ripening is moderately uniform with a heavy fruit set rating.  Fruits are sweet to taste.  

Captain produces first fruit 31 days after transplanting.  Maximum fruit production occurs within 2 weeks after first harvest but production continues for 2-3 weeks after the maximum period.  Yield of up to 60 t/ha are obtained with each plant producing up to 1.45 kg fruit.  Shows good producing ability under wet conditions.

Local Variety

This is an early to medium maturing variety.  Plants are intermediate in height (72 cm) producing medium to large fruits (59 g).  Fruits are segmented (some smooth) and are slightly flattened in shape; they are soft, very susceptible to growth cracking and considered to be "bitter" in taste.

Fruit setting is rated as medium with peak harvest occurring within a 4 week period.  Under good growing conditions, yield can reach as high as 56 t/ha.  Twenty one fruits may be produced per plant giving an average yield of 734 g/plant.  The variety is moderately susceptible to bacterial and fusarium wilt.  i.e. not many plants will be affected by these diseases.

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