Sme. Satti et al., ENHANCEMENT OF SALINITY TOLERANCE IN TOMATO - IMPLICATIONS OF POTASSIUM AND CALCIUM IN FLOWERING AND YIELD, Communications in soil science and plant analysis, 25(15-16), 1994, pp. 2825-2840
Five tomato (Lycopersicon esculentum Mill ) cultivars were grown in sa
nd nutrient culture experiment in a greenhouse to investigate the effe
cts of salinity on growth and yield. Nutrient solutions were made sali
ne with 50 mM NaCl (EC = 5.5 mS/cm or supplemented with 2 mM KNO3 (EC
= 6.8), 20 mM Ca(NO3)2 (EC = 7.5), and combination of potassium (K) an
d calcium (Ca) (EC = 8.0). Seedlings were irrigated with saline treatm
ents commencing two weeks after transplanting. Determination of sodium
(Na) and K in tomato leaves and fruits were by flame photometry. Accu
mulation of Na in tomato fruits was higher than in leaves under contro
l or saline conditions for all tomato cultivars. The amount of K in th
e tomato leaves was higher in control than in saline-grown plants. Add
ition of K and Ca to the nutrient solution resulted in a 3 to 7 fold i
ncrease in K accumulation in all cultivars tested. Stem and leaf growt
h were significantly reduced with salinity but growth was enhanced fol
lowing irrigation when K was added to the nutrient solution. Flowering
and fruit set were adversely affected by NaCl stress. Reduction of fl
ower number was 44% relative to the control plants. Fresh fruit yield
decreased by 78% when plants received 50 mM NaCl. Growth and developme
nt of tomatoes under saline conditions was enhanced in this study foll
owing the application of K to the saline nutrient solution. Ameliorati
on in growth was also achieved when Ca was used but to a lesser extent
. Our results suggest that ion accumulation and regulation of K and Ca
contribute to salt tolerance and growth enhancement.