Nutrient seed priming effects on the germination rate, seedling vigour, early growth, nutrient uptake and water stress tolerance of chillies (capsicum annum l.)

Capsicum annuum L. (chilli) is a widely cultivated and high-demand crop in South Africa, offering considerable income potential to smallholder farmers. However, its productivity remains low due to poor seed germination, weak seedling vigour, and environmental stress factors such as water scarcity. Nutrient seed priming (NSP) is a pre-sowing technique that has emerged as a promising agro-technological intervention to enhance germination, seedling establishment, nutrient uptake, and stress tolerance in chilli production. This study investigated the effects of different concentrations and priming durations of zinc oxide (ZnO) and potassium nitrate (KNO₃) seed priming solutions on germination, early growth, and nutrient uptake of chilli seedlings under laboratory and glasshouse, conditions. For the laboratory trial an 8x4 factorial treatment was used with five ZnO concentration, three KNO3 concentration and three priming durations. Laboratory trials revealed that NSP significantly improved germination indices, with 10 mg/L ZnO enhancing germination energy by 62.12% compared to higher concentrations, significantly higher effect were observed at ZnO 20 mg/L in all the other measured germination indices (Germination rate, mean germination time and germination rate index). The best performing treatments ZnO 10 mg/L, ZnO 20 mg/L and KNO3 10 g/L were then used in the glasshouse study. In this glasshouse experiment, a 5x3 factorial treatment was used, the best performing treatment two ZnO concentration, one KNO3, a positive control (H2O) ,negative control (no priming) and three priming duration. Priming with 20 mg/L ZnO for 6 hours yielded greater seedling performance in terms of shoot height, root length, fresh seedling weight, and stem diameter. Duration notably influenced fresh biomass accumulation, suggesting the availability of ZnO during early development facilitates resource allocation for growth, the best performing concentration from each nutrients with the best performing priming duration where then used on the water stress trial. Further trials under controlled moisture conditions (30%, 50%, and 80% field capacity) assessed nutrient uptake efficiency. Results showed that priming with KNO₃ and water significantly enhanced nitrogen, phosphorus, and potassium uptake, while ZnO priming increased nitrogen and phosphorus uptake by 54.63% and 25.7%, respectively, compared to controls. However, Zn uptake was reduced in ZnO-primed plants, suggesting a complex interaction between priming treatments and soil moisture levels. Overall, NSP, particularly with KNO₃ and ZnO proved effective in improving chilli seedling vigour, early growth, and nutrient acquisition, especially under water stress. These findings underscore the need for crop-specific and moisture-sensitive priming protocols to optimize chilli productivity in smallholder systems

M. Sc. (Agriculture)

Agriculture and  Animal Health