The search for sources of tolerance or resistance to salinity in genotypes of wild species related to the cultivated tomato continues to occupy our attention (Anastasio et al., 1988). Genetic studies and breeding programs using interspecific variability are being carried out by our work team, given the growing problem of salinization of soils and waters in some areas of our country.
With this objective, an experiment was carried out in 1987, in Alhama Murcia (Spain) which included: 22 accessions of L. pimpinellifolium (originating from Peru) and 8 accessions of L. peruvianum (originating from Peru). The experiment was designed in random blocks with 3 repetitions and 5 plants per plot. The crop was cultivated in open air in a parcel with high salinity, as is shown in the results of electrical conductivity testing (Abrisqueta et al., 1962) carried out on four different dates: The 1st analysis was taken before sowing the crop 29th February); 2nd analysis, during the transplanting (31st May); the 3rd analysis, near a month after transplanting (23rd June); the 4th analysis, the 22nd of September, in each plant that produced fruit. The average EC\e\ values (saturation extract and the limits of variation in each analysis were (Table 1):
Table 1. Averages and limits of variation of EC\e\ (dS/m) in the soil
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1st 2nd 3rd 4th
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Average (ECe) 61.2 21.6 26.4 42.9
Limits of variation 43.7-72.2 18.5-24.8 21.5-40.9 38.6-49.3
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The crop watered with fresh water was left unwatered intentionally after it
had been transplanted for near a month (23rd June). This explains the
noticeable increase in salinity at the end of the productive period.The characteristic measured was the survival on two dates: 2 weeks after transplanting and at the end of the biological cycle. All the plants for which fruit reached maturity belonged to the L. pimpinellifolium species, specifically the accessions PIM-847, PIM-850, PIM-1135 and PIM-2350. Taking into account that the physiological mechanisms involved in tolerance may be different according to the level of salinity employed (Jones & Qualset, 1984; Shannon et al., 1987), these selected genotypes will be exposed to a new test in controlled conditions with hydroponic cultivation in sand and various salinity treatments. While tolerance to other concentrations of salinity are being confirmed, crossing of tomato cultivars has been started in order to derive possible breeding lines in the future.
Acknowledgement: This work was supported by the research project CA 0917/84 held by the CAICYT. We thank J.A. Martinez (S.E.A., Alhama Murcia) for his useful collaboration.
Literature cited:
Abrisqueta, C; M.J. Guillen; F.G. Fernandez and M. Caro. 1962. An. Edaf. Agrob. XXI, 545 554.
Anastasio, G.; C. Pellicer; M.S, Catala; J. Costa; G. Palomares and F. Nuez. 1988. TGC 38: 5-7.
Jones, R.A.; C.O. Qualset. 1984. In "Application of genetic engineering to crop improvement". G.B. Collins & J.G. Petolino (Ed-s), The Netherlands, pp. 304 340.
Shannon, M.C.; J.W. Gronwald and M. Tal. 1987. Journal of the Amer. Soc. Hort. Science (1987) 112(3), 416 423.