Effect of Calcium and Potassium Nutrition on Yield,Ion Content,and Salt Tolerance of Brassica campestris (rapa) |
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Authors: | R P Collins P J C Harris M J Bateman J Henderson |
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Institution: | 1. Faculty of Business, Environment and Society , Coventry University , Coventry , UK;2. Faculty of Health and Life Sciences , Coventry University , Coventry , UK |
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Abstract: | When plants encounter salinity, growth is reduced initially by water stress and subsequently by toxic levels of ions and by interference with nutrient acquisition and translocation. Calcium (Ca2 +) in particular seems to have an important role in salt tolerance and there are reports of a beneficial effect of increasing Ca2 + availability. Higher potassium (K+) concentrations in plants may also improve salinity tolerance as sodium (Na)+/K+ ratios have been shown to be important. Previous work with a range of Acacia species has suggested that endogenous seed Ca2 + and K+ concentrations might influence salinity tolerance at germination, but this has not previously been tested with a single species. The objectives of this investigation were thus to determine whether (1) altered Ca2 + and K+ nutrition of Brassica campestris (rapa) L. plants affects the yield and ion content of their seeds, and (2) seeds with different Ca2 + and K+ contents differ in their salinity tolerance. Plants were grown in a growth room or greenhouse in (1) Gem® horticultural sand (2) Silvaperl® perlite and sand (2:1), or (3) Shamrock® Medium General Purpose Irish Sphagnum Peat and Vermiperl® vermiculite (1:1). Plants in each growth substrate were supplied with nutrient solutions based on a modified Hoagland's solution as a control, low Ca2 + and low K+ solutions containing those elements at half the control strength, but all other mineral elements as far as possible at control strength, and high Ca2 + and high K+ solutions containing those elements at double control strength but all other mineral elements, as far as possible, at control strength. An increase in substrate available Ca2 + and K+ resulted in increased Ca2 + and K+ concentration in seeds, respectively, and was accompanied by a reduction in seed K+ and Ca2 +, respectively. The Ca2 + and K+ concentrations of seeds affected their salinity tolerance. Increases in seed Ca2 +, K+ or Ca2 ++ K+ concentrations decreased salinity tolerance at germination. The results, especially in terms of Ca2 + nutrition, contradict previous results of an increased salinity tolerance with increased Ca2 + and/or K+ concentrations. |
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Keywords: | Brassica campestris (rapa) calcium plant nutrition potassium salinity tolerance seed germination |
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