'On-Farm’ Seed Priming: A Strategy for Ecological & Sustainable Agriculture

Abstract

There is an urgent need to intensify food production globally and reduce our reliance on synthetic agronomical inputs. Crop establishment is the most vulnerable stage in the crop cycle, therefore, sustainable strategies with the potential to alleviate unfavourable seedbed conditions are crucial to ensure yield potential is not restricted early in the season. Industrial seed priming is an effective strategy, but it is both energy-intensive and expensive. ‘On-farm’ seed priming offers a low-cost alternative; however, it is commonly underutilised in the developing world, and it has never before been evaluated in a European agricultural context. Therefore, this thesis sought to determine the potential contribution of ‘on-farm’ seed priming to increase food production in the developing world. In addition, the aim was to assess the effectiveness of ‘on-farm’ seed priming together with chitosan (an organic plant elicitor) to sustainably intensify barley (Hordeum Vulgare L.) production in conventional European agrosystems. Quantitative analysis showed that ‘on-farm’ seed priming had a significant positive effect on crop yields (on average, a 21 % increase over farmers’ practice) in the developing world, and was most effective in dry climates, and nutrient deficient or salinity-stressed environments. In European conventional barley systems, ‘on-farm’ seed priming and chitosan-based seed treatments enhanced spring barley yields through improving emergence and seedling vigour, and led to a greater number and size of tillers being retained for grain filling. By contrast, winter barley did not benefit from seed priming treatments. Although seed treatments can promote emergence, it is likely that they alter the adaptative mechanism for overwinter acclimation and result in a fitness cost. It was found that a greater canopy size can provide a certain degree of tolerance to pre stem elongation powdery mildew (Blumeria graminis) infection and that rapid stem elongation limited secondary spreads of powdery mildew and, hence, provide a certain level of disease escape. Overall, this thesis provides the evidence for governmental institutions and policymakers in developing countries to promote ‘on farm’ seed priming as a recommended practice. In a European agricultural context, seed treatments can be included as one more management practice in spring-sown crops to ensure that yield potential is not restricted early in the season. Seed treatments may deliver disease tolerance and escape traits, but these benefits will be conditional upon conferring successful establishment and vigour first.