Predicting seedling emergence of cabbage and onion using vigour tests

Abstract

Predicting seedling emergence using standard and non-standard germination temperatures, standard accelerated ageing (AA) and saturated salt accelerated ageing (SSAA) tests, were investigated. Germinations were performed at temperatures of 10°, 20°, 20°/30° and 30°C for cabbage (Brassica oleracea var. capitata L.) and 10°, 15°, 20° and 30°C for onion (Allium cepa L.). Seeds were aged using relative humidities of 32% (RH32), 43% (RH43), 75% (RH75) and 100% (RH100). Emergence trials were conducted at a range of temperatures (winter, 15°/25° and 30°C) and growth media. Most SSAA vigour tests were useful in differentiating seed lots based on their physiological stage of deterioration. In the SSAA tests, the seed moisture content remained below 14% and no fungal growth occurred. For cabbage, highly significant correlations were obtained between 10°C and RH32 and all emergence trials. For onions highly significant correlations with emergence percentage were obtained with germinations at 15° and 30°C. Mean germination time (MGT) and germination energy (GE) were valuable in categorising seed lots with moderate vigour levels, however, only GE revealed good correlation with winter emergence trial of onions.

Crop physiology: A perspective for southern Africa

“…Membrane integrity is improved early following uptake of water during germination (Mayer & Marbach, 1981;Mazibuko & Modi, 2005). Inability of membranes to maintain integrity results in leakage of substances (Modi, 2004a,b) and subsequent pathogen infection (Fessehazion et al, 2008), which indicate poor seed quality. A general scenario of metabolic events during seed germination has been reviewed (Obroucheva & Antipova, 1997), including the permissive role of gibberellic acid and inhibitory effect of abscisic acid.…”