Roots to resilience: climate-proofing crop yields within future salad production

气候变化已经并将导致更极端的气候条件(例如，2018年63%的长期平均降雨量和蒸散量增加了13%)，威胁到英国户外沙拉生产的弹性。生菜是浅根的，室外作物最初在苗圃的泥炭区种植，然后移植到精心准备的苗床中，如果移栽后出现热浪条件，苗床很容易土壤干燥。快速生根对于确保从苗床吸收足够的水分(减少对泥炭块中储存的水的依赖)并允许减少灌溉频率(以减少蒸发损失)至关重要，因为根部从深处提取水分。苗圃条件是如何影响生菜移栽生根的，人们的兴趣有限。泥炭收获对环境的影响给生菜产业带来了压力，要求其减少对泥炭作为生长基质的依赖。几种不含泥炭和减少泥炭的基质现已可用(Barrett等人。2016；科学。小矮人。212,220-234)，移栽块大小可能会减小，但它们对移栽(苗圃内外)根系发育的影响研究很少。移栽生产方式的改变可能需要改变灌溉制度，以提高水分利用效率。高频灌溉可以最大限度地促进新梢生长，但可能会以牺牲根系发育和质量为代价，同时降低水分利用效率。在任何修改后的生产系统中，都需要在经济产量(由作物大小与口味决定)和可持续性之间进行权衡。本项目旨在评估：1.现有生产系统下的生菜根系发育如何影响田间的水分提取模式2。苗圃环境条件影响生菜移栽后的根部生长，并决定其潜在的生理机制。灌溉频率影响作物的产量、品质和田间水分利用效率。

Climate change has and will result in more extreme climatic conditions (e.g. 2018 had 63% of the long-term average rainfall and evapotranspiration increased by 13%) that threatens the resilience of UK outdoor salad production. Lettuce is shallow-rooted, with outdoor crops initially raised in peat blocks in the nursery, then transplanted into intensively prepared seedbeds that are vulnerable to soil drying should heatwave conditions occur after transplanting. Rapid root establishment is critical to ensure adequate water uptake from the seedbed (decreasing reliance on water stored in the peat block) and allow less frequent irrigation (to minimise evaporative losses) as roots extract water from depth. How nursery conditions affect root establishment of lettuce transplants has attracted limited interest.The environmental impacts of peat harvesting place pressure on the industry to decrease its reliance on peat as a growing substrate. Several peat-free and peat-reduced substrates are now becoming available (Barrett et al. 2016; Sci. Hort. 212, 220-234), and transplant block size may be reduced, but their effects on root development in transplants (both in and out of the nursery) has seen little research.Changes in transplant production methods may require altered irrigation scheduling to increase the efficiency of water use. High frequency irrigation can maximise shoot growth at the expense of root development and possibly quality, while lowering water use efficiency. A tradeoff between economic yield (determined by crop size versus taste) and sustainability is needed in any amended production system. This project aims to evaluate how:1. lettuce root development under existing production systems affects water extraction patterns in the field2. nursery environmental conditions affect root growth in lettuce transplants in situ, and in the field after transplanting, and determine the underlying physiological mechanisms3. irrigation frequency affects crop yield, quality and water use efficiency in the field.