Possibilities of genetic re-improvement in open pollinated processing tomato cultivars: a case study from Turkey


DUZYAMAN E. , DUMAN I. , GUMUS M. , Esiyok D. , VURAL H.

EUROPEAN JOURNAL OF HORTICULTURAL SCIENCE, cilt.71, ss.199-206, 2006 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 71 Konu: 5
  • Basım Tarihi: 2006
  • Dergi Adı: EUROPEAN JOURNAL OF HORTICULTURAL SCIENCE
  • Sayfa Sayıları: ss.199-206

Özet

Open-pollinated (OP) processing tomato cultivars are preferred in Turkey by resource-poor farmers. Seven seed or tomato paste companies (14% of the total) were found to be still distributing OP seeds. Seed samples of 38 different seedlots from a total of 6 cultivars ('C-37', 'Interpeel', 'Rio Fuego', 'Rio Grande', 72 Improved' and 'VF 6203') were collected. Only 68.4% of the seed sources (26 seedlots) were free of seed-borne viral (tomato mosaic virus) or bacterial (Clavibacter michiganensis subsp. michiganensis) pathogens. In replicated field trials, conducted in the districts of Karacabey (Marmara Region) and Muradiye (Aegean Region), seedlots of OP cultivars were generally inferior to F, hybrids ('Brixy', 'NDM 055' and 'Shasta') in yield and technological traits. In principal component (PC) analysis, F, hybrids were the most separated group, while the phenotypes of some OP seedlots were more heterogenic. Hybrids were mainly separated by the 1st PC axis which mainly contains yield and degrees Brix x yield (degrees BxY). Besides source-specific genetic differences, high degrees of phenotypic variances for yield were also present within most seedlots. Cultivar purity is apparently lost following many seed multiplication cycles carried out by the seed companies and/or the farmers. A comparison of selected populations with their original populations revealed that selection significantly increased yield and degrees BxY in all cultivars. Possibilities for genetic re-improvement are also discussed.