Application of innovative plant breeding and phenotyping to reduce the nutrient requirement of forages and improve livestock production efficiency

Forage crops such as perennial ryegrass and white clover are the major feed of UK livestock and an important component of sustainable ruminant production. Grassland covers 11million ha of the UK landmass of which 1.2million ha is <5 years old, with 325,000ha resown annually with varieties of forage grasses and legumes (Defra). The major emphasis of grassland agriculture has been on increasing dry matter yield, forage quality and animal production. Greater EU regulation means the UK grassland sector is now faced with reducing the environmental impact of production whilst simultaneously improving its production and efficiency. The effective use of nutrients is one of the key components of efficient grassland management, with the application of nitrogen (N) and phosphorus (P) integral to maintaining the productivity of high quality swards. Livestock farmers are being encouraged to produce more from forage, while less predictable fertiliser prices, may act to increase costs. This project will address the challenge of increasing the sustainable intensification of grassland agriculture through applying plant breeding and genomics technologies in parallel with enhanced phenotying technologies, within the NPPC to improve the nutrient use efficiency of perennial ryegrass and white clover varieties. Fertiliser inputs to grassland depend upon system and management regime. Nitrogen prices are currently £270/t or 78p/kg N. Application rates range widely: a standard range would be 160kg to >204kg N ha/year depending upon stocking rate, concentrate use, manure application and use of forage legumes. Improving the use of N and P in UK grassland systems through targeted plant breeding is a major challenge but also presents a significant opportunity for plant breeders. This project will exploit outcomes of earlier research on perennial ryegrass and white clover that has developed novel genetic resources and breeding technologies that will enable selection for improved nutrient use eficiency in forages, leading to varieties of perennial ryegrass and white clover requiring less N and P per unit of dry matter production, providing an economic benefit to primary producers and environmental benefits. The project will use the National Plant Phenotyping Centre at Aberystwyth University (AU) to analyse the effect of selection on NUE on single plants prior to seed production and evaluation in field trials and validation of the outcomes through optimised nutrient management. The enhanced germplasm developed will be exploited beyond the project (within 5 years of completion) by Germinal Holdings Ltd. (GHL) to produce finished varieties marketed by GHL in UK and overseas, potentially increasing the use of their varieties by 10% (currently GHL supply 30% of UK forage seed market of 10000t).

Initial studies in flowing solution culture and in the National Plant Phenomics centre has shown considerable genetic variation in nutrient use efficiency in perennial ryegrass (nitrogen) and for white clover (phosphorus). Results obtained from phenotyping this germplasm will be combined with ongoing genetic analysis in order to produce robust genetic markers for nutrient use efficiency in both species. In a parallel strand of work in this project a breeding population of white clover (Ac 5192) has been derived from plants performing well in a low-P field area. Further selections have been made from this germplasm (summer 2017), and these are being refined for further use in the white clover breeding programme (ongoing). In both species, markers identified for nutrient use efficiency will be applied to select new populations to strengthen existing breeding programmes.