Leaf Blade Growth and Development in Red, Pink, and Yellow Petiole Cultivars of the Swiss Chards Grown in Floating Culture System.

Adaptability of the Swiss chard to the tropical climate opens opportunity to grow this leafy vegetable all year around. Colorful petiole and leaf blade of this vegetable have attracted urban community to grow them. Objectives of this research were to study the morphological and growth characteristics of the Swiss chard, especially leaf growth rate, time to reach full size, and non-destructive measurement of the leaf area. The Swiss chards used were red, pink, and yellow petiole cultivars. The plants were cultivated using the floating culture system. Relative leaf elongation and widening rates were higher at early leaf development, i.e. soon after the leaf blade was unfolded. Then, the rates were gradually declined and completely halted at about 12 days. In this study, combination of the zero-intercept linear model and the length × width (LW) as predictor were accurate for estimation leaf area (LA) of the red (R² =0.981), pink (R² =0.975), and yellow (R² =0.980) petiole cultivars. The non-destructive measurement on selected morphological and/or weight traits should be useful for continuously monitoring of leaf growth, predicting yield at any time during plant growth, and determining the time to harvest. [ABSTRACT FROM AUTHOR]