Short-term preservation of maize landrace seed and taro propagules using indigenous storage methods

摘要

Some native subsistence farmers in South Africa store maize (Zea mays L.) cobs over a fireplace and subject the seeds to smoke and heat. Taro (Colocasia esculenta L. Schott.) propagules are maintained in dry pits for one month, in layers separated by grass straw, and water is prevented from contacting them. These methods have been used together with others to maintain landraces for centuries, but they have largely been abandoned with no modern technology replacements. The objective of this study was to examine the effects of the maize and taro storage methods on the quality of planting material. Experiments were conducted on three subsistence farms located in KwaZulu-Natal, and at the University of KwaZulu-Natal, South Africa. Two maize landraces, yellow and white, were subjected to the smoke-over-fire storage method for five months during the normal off-season period for maize production in the location. Control maize seeds were stored in unsealed containers away from fire and smoke. Taro propagules of different sizes (80-100g corm(-1), 40-60g corm(-1) and 20-30g corm(-1)) were compared for storability in dry pits, in layers separated by grass straw, for one month. Subsequently, sprouted corms were stored in dry conditions to allow shoot development. During maize seed storage, water content was determined monthly. Maize seed quality was determined by viability, germination and seedling vigour. Sprouting and rooting during taro pit storage, and main shoot development during air storage were used to determine taro propagule performance in storage. Seeds that were stored over fire and smoke showed higher germination and vigour that non-smoked seed. Sprouting and shooting of taro propagules were better in large propagules and the optimum storage depth was 35cm to 40cm. alpha-amylase activity increased during pit storage and declined to almost the pre-storage levels during shoot growth period outside the pits, in all corm sizes. It is concluded that smoke and heat storage improve maize seed quality and pit storage enhances taro propagules by inducing sprouting. Data from this study can be used to investigate the physiological and biochemical basis of seed and propagule quality enhancement, and possibly contribute to technological inventions that are based on indigenous knowledge systems.