Effects of Different Irrigation Waters and Silicon Doses on Leaf SPAD Meter Readings, Chlorophyll and Carotenoid Contents of Tomato Plants

Abstract

This study was conducted to determine the effects of different irrigation water treatments and silicon doses on leaf SPAD meter readings, chlorophyll content and carotenoid contents of tomato plants. Tybiff Aq tomato seedling were grown in 3-liter pots filled with 1100 g of 1:1 peat-perlite mixture for 70 days. Four different type of irrigation waters were prepared with the use of sea and tap water. Irrigation waters included I) Full sea water, II) ½ sea water + ½ tap water, III) ¼ sea water + ¾ tap water, IV) Full tap water (control). Each irrigation water was supplemented with silica gel (SiO2.xH2O) at 0, 0.5, 1 and 2 mM Si doses. Nutrient solutions were supplied to meet macro and micronutrient requirements of tomato plants. Leaf chlorophyll-a, chlorophyll-b and total chlorophyll contents significantly increased with increasing tap water ratios of the irrigation water. Significant increases were observed in chlorophyll-a, chlorophyll-b and total chlorophyll contents with increasing silicon doses. Such increases achieved with silicon treatments were more remarkable for chlorophyll-a and total chlorophyll contents. Leaf chlorophyll-a, chlorophyll-b and total chlorophyll contents significantly decreased with increasing leaf sodium, chlorine and magnesium contents, but significantly increased with increasing leaf active iron and potassium contents. Leaf chlorophyll-a, chlorophyll-b and total chlorophyll contents increased with increasing leaf calcium contents, but such increases were not significant. Leaf carotenoid contents significantly increased with increasing tap water ratios of the irrigation water. Effects of silicon doses on leaf carotenoid contents varied with the type of irrigation water. The 0.5 mM silicon supplementation into tap water significantly increased carotenoid contents.