Cucurbit Genetics Cooperative Report 7:49-50 (article
Effect of Methodology on Expression of Intercultivar Differences
in Response to NaCl Stress in Melons
H. Nerson, H.S. Paris, Z. Karchi, Y. Burger, and M. Edelstein
Department of Vegetable Crops, Agricultural Research
Organization, Newe Ya'ar Experiment Station, P.O. Haifa, Israel
Most vegetable crops are sensitive or moderately sensitive to
salinity (1). Melons are classified as moderately tolerant (3)
and are a potential crop for irrigation with saline water (2).
Sources of salt tolerance within a crop must be identified as the
first step in a breeding program whose goal is to develop
cultivars having higher salt tolerance. Several methods of
screening and selection for salt tolerance have been evaluated
for many crops (4).
Our objective was to compare responses of four melon accessions
from diverse genetic backgrounds to salinity stress induced by
three screening methods, and to relate these results to field
test results. Accessions compared were the Israeli muskmelon
'Galia', the Israeli casaba 'Noy 'Amid', the European casaba
'Rochet', and a muskmelon introduction from Iran designated
"Persia 202". The three screening methods were: (a) Seedlings
were grown in 250 ml pots filled with fine gravel which were put
in slightly larger pots containing Hoagland solution. At the
first leaf stage (about ten days after emergence), NaCl at the
rate of 10,000 ppm was added to the nutrient solution, which was
renewed every other day. The pots were placed in growth chambers
at two temperature regimes (day/night), 31C/23C and 23C/15C,
with a 12-hour photoperiod. (b) Similar to a except
that the pots were filled with a 4:1 (by volume) mixture of local
silty loam:vermiculite at two salinity levels, 10,000 and 15,000
ppm, and (c) Seedlings were grown in larger pots (600 ml), in the
greenhouse, with the same mixture as in b. NaCl at
15,000 ppm was introduced at the same developmental stage as in a and b but by daily application of
50 cc/pot in the nutrient solution.
Fourteen days after the beginning of salinization, plants were
analyzed for growth, the data being presented in Table 1.
Comparison of control results among the various methods revealed
three different levels of seedling growth. The most favorable
conditions were in c (larger pot, fertile medium,
and high radiation) while the poorest were in a (small pot, hydroponic, inert medium, and relatively low
radiation). Differences among accessions in response to NaCl
stress were inconsistent among the three methods. For a given
method, the most clear-cut difference occurred in c, where 'Rochet' was far superior to the other
Table 1. Effect of three methods of NaCl application on absolute
growth (mg dry weight) and relative growth (% of control) of four
melon accessions, 14 days after salinity introduction.
Salinity level (ppm NaCl)
zAverage of temperature regimes (see text). Mean separation in
relative growth (%) columns by Duncan's multiple range test, 5%
The two casabas, 'Rochet' and 'Noy Amid', were compared in a
field experiment for sensitivity to salinity. Expressed in terms
of percent yield reduction, 'Rochet' was less sensitive to
salinity than 'Noy 'Amid', consistent with the performance of
these two cultivars in method c. This suggests that
screening for salt tolerance should be conducted under as near to
optimal growing conditions as possible. Such conditions would
reduce confounding effects of various other environmental
stresses and enable each accession tested to express its full
- Maas, E.V. and G.J. Hoffman. 1977. Crop salt tolerance--current
assessment. J. Irrig. Drain. Div., Amer. Soc. Civil Engin.
- Pasternak, D., I. Borovic, Y. De-Malach, and A. Davidson. 1980.
Production of melons in the Negev Highlands with brackish water
for summer and early autumn export. Hassadeh 61:133-138 (in
Hebrew with English abstract).
- Shannon, M.C. and L.E. Francois. 1978. Salt tolerance of three
muskmelon cultivars. J. Amer. Soc. Hort. Sci. 103:127-130.
- Shannon, M.C. 1979. In quest of rapid screening techniques for
plant salt tolerance. HortScience 14:587-589.
Contribution No. 980-E, 1983 series, from the Agricultural
Research Organization, Bet Dagan, Israel.