Seedling Growth as Affected by Seed Weight in Common Vetch

Abstract

AbstractGrowth pattern of seedlings is important for any species to achieve successful establishment. Growth chamber experiments were conducted to study the relationships between seed weight and usage of cotyledonary reserves and growth rates of major seedling components and to determine the changes in relative importance of cotyledonary reserves and newly developed photosynthetic tissues on seedling growth in common vetch (Vicia sativa L.). Seedlings from three seed‐weight groups of ‘Warrior’, PI 284563, and ‘Cahaba White’ were grown in growth chambers at a temperature of 28/12°C under complete darkness and light–dark cycle (13/11 h) conditions. Seedlings from heavier seeds utilized cotyledonary reserves (UCR) at a faster rate; however, conversion efficiency of cotyledonary reserves (CECR) into plant tissue was the same regardless of seed weight. Hence, the advantage of heavy seeds lies in their higher content of cotyledonary reserves and on their ability to provide energy more rapidly to the growing seedlings. Seedlings from heavier seeds had greater rates of elongation, accumulation of leaf area and shoot, leaf, and root dry weights than those from light seeds. Thus, heavier seeds produce seedlings with a higher growth capacity in common vetch. Cotyledonary reserves supported heterotrophic seedling growth for ≈7 d after emergence (DAE) under dark conditions. However, cotyledonary reserves had little importance in subsequent growth once the first tetrafoliolate leaf emerged at 5 DAE for light‐grown seedlings. Thus, the emergence of the first tetrafoliolate leaf marks the transition between heterotrophic and autotrophic seedling growth.