Some Lycopersicon accessions were found in previous studies to be relatively salt-tolerant including L. esculentum cv 'Edkawy' (Hassan and Desouki, 1982; Mahmoud et al, 1986a, 198b), 'Yusupovskii' and 'Karlik' (Sinel'nikova et al., 1983) and P.I 174263; L. exculentum ssp. cerasiforme line CER 2022 (Anastasio et al., 1988); L. pimpenellifolium accessions PIM-2350, PIM-1135, PIM-85 and PIM-847 (Costa et al., 1989) and some other wild accessions including L. peruvianum P.I 126435, L. cheesmanii ssp minor LA 1401 and L. pennellii P.I. 1246502 and LA 716 (Dehan and Tal, 1978); Sacher, 1983; Tal and Shannon, 1983; Rush 1986; Jones 1986; Saranga et al., 1987). However, L. chessmanii ssp. minor LA 1401 was found to be more sensitive to high salinity than tomato cvs Hassan and Desouki, 1982; Mahmoud et al., 1986b). The objectives of this study were: a)to develop an easy evaluation method for salinity tolerance in the seedling stage, and b) to use the developed method in screening for tolerance in 7 Lycopersicon species.
The study was performed at U.A.E. University (U.A.E.) under controlled conditions in a biotron (LH-200-RDCD). Plants were grown in jiffy pots (4x4x 5 cm depth) filled with potting compost. Temperature was maintained at 24 deg.C for the first 2 weeks after seed sowing and at 24 deg.C/21 deg.C (12 hr day/12 hr night) thereafter. Increasing irrigation water salinity of 15-day old 'VFN 8" tomato seedlings from EC 1 mS/cm (control treatment) to EC 6 ms/ cm did not affect seedlings survival, though it casued 31.5% increase in seedling dry weight. Further increases in salinity caused a gradual increase in seedling death rate which readched about 50% with 15 mS/cm treatment 1 month after the beginning of the salinity treatment. Hence accessions showing less than 50% death rate under similar conditions may be considered as relatively salt-tolerant.
This evaluation mehtod was used for screening 106 Lycopersicon accessions which included 9 tomato cultivaers, 1 line of each L. esculentum ssp. cerasiforme, L. chmielewskii and L. pennellii, 70 of the L. pimpinellifolium, 12 of the L. hirsutum, 2 of the L. parviflorum and 10 of L. peruvainum. Seeds were kindly provided by local dealers for tomato cultivars, Dr. C.M. Rick for LA accessions, and the U.S.D.A. for the P.I. accessions. Accessions were evaluated in 5 test performed in the biotron during the perido from October, 1988 to June, 1989. Five jiffy pots were used for entry. Seedlings were thinned 2 weeks after sowing to 2-5/pot. Irrigation with saline water (EC= 15 mS/cm) started after thinning and lasted for 1 month. Data were recorded on death rate at the end of the experiment.
Seedilings death rate varied for 0.0% to 79% among tomato cvs. However, their performance, in individual tests, provided a preliminary indication of the relative tolerance of wild accessions evaluated with them in the same tests. Hence, the following accesssions were condidered as salt-tolerant: L. esculentum ssp. cerasiforme LA 1310 and L. pimpinellifolium LA 1579 and P.I. 365967. The following accessions were also considered as relatively tolerant: L. pimpinellifolium P.I. 309907, P.I. 265959, P.I. 375937, P.I. 379023, P.I. 379025; and P.I. 39716; L. hirsutum P.I. 365907 and P.I. 365934; L. peruvianum P.I. 306811 and L. chmielewskii P.I. 379030. To our knowledge, none of these accesssions has been previously reported as salt-tolerant.
Literature cited:
Anastasio, G., P. Pellicer, M.S. Castala, J. Costa, G. Palomares and F. Nuez 1988 Tomato Genetics Cooperative Rep. 38:5-7.
Costa, J., M.A. Sanchis, G. Palomares and F. Nuea 1989 Tomato Genetics Cooperative REp. 39:8-9.
Dehan, K. and M. Tal 1978 Irrigation Sci. 1:71-76.
Hassan, A.A. and I.A.M. Desouki 1982 Egypt. J. Hort. 9:153-162.
Hassan, A.A. and I.A.M. Desouki 1986 Egypt J. Hort. 13:159-170.
Jones, R.A. 1986 Euphytica 35:375-582.
Mahmoud, M.H., A.S. El-Beltagy, R.M. Helal and M.A. Maksoud 1986a Acta Hort. 190:559-566.
Mahmoud, M.H., R.A. Jones and A.S. El-Beltagy 1986b Acta Hort. 190:533-543.
Rush, D.W. 1986 Diss. Abstr. Inter. B46:4088B.
Sacher, R.F., R.C. Staples and R.W. Robinson 1983 J.Amer.Soc.Hort.Sci 108:566- 569.
Saranga, Y., J. Rudich and D. Zamir 1987 Acta Hort. 200:203.
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Tal, M. and, M.S. Shannon 1983 Aust.J.Plant Phys. 10:109-117.