Vleugels Tim, Saleem Aamir, Dubey Reena, Muylle Hilde, Borra-Serrano Irene, Lootens Peter, De Swaef Tom, Roldán-Ruiz Isabel
ILVO (Flanders Research Institute for Agriculture, Fisheries and Food), Plant Sciences Unit, Melle, Belgium.
Front Plant Sci. 2024 Jan 12;14:1304411. doi: 10.3389/fpls.2023.1304411. eCollection 2023.
Red clover () is a protein-rich, short-lived perennial forage crop that can achieve high yields, but suffers increasingly from drought in different cultivation areas. Breeding for increased adaptation to drought is becoming essential, but at this stage it is unclear which traits breeders should target to phenotype responses to drought that allow them to identify the most promising red clover genotypes. In this study, we assessed how prolonged periods of drought affected plant growth in field conditions, and which traits could be used to distinguish better adapted plant material.
A diverse panel of 395 red clover accessions was evaluated during two growing seasons. We simulated 6-to-8-week drought periods during two consecutive summers, using mobile rain-out shelters, while an irrigated control field was established in an adjacent parcel. Plant growth was monitored throughout both growing seasons using multiple flights with a drone equipped with RGB and thermal sensors. At various observation moments throughout both growing seasons, we measured canopy cover (CC) and canopy height (CH). The crop water stress index (CWSI) was determined at two moments, during or shortly after the drought event.
Manual and UAV-derived measurements for CH were well correlated, indicating that UAV-derived measurements can be reliably used in red clover. In both years, CC, CH and CWSI were affected by drought, with measurable growth reductions by the end of the drought periods, and during the recovery phase. We found that the end of the drought treatment and the recovery phase of approximately 20 days after drought were suitable periods to phenotype drought responses and to distinguish among genotypes.
Multifactorial analysis of accession responses revealed interactions of the maturity type with drought responses, which suggests the presence of two independent strategies in red clover: 'drought tolerance' and 'drought recovery'. We further found that a large proportion of the accessions able to perform well under well-watered conditions were also the ones that were less affected by drought. The results of this investigation are interpreted in view of the development of breeding for adaptation to drought in red clover.
红三叶草()是一种蛋白质含量丰富的一年生短期多年生饲料作物,产量较高,但在不同种植地区日益受到干旱影响。培育更适应干旱的品种变得至关重要,但目前尚不清楚育种者应针对哪些性状来表型干旱反应,以便识别最有前景的红三叶草基因型。在本研究中,我们评估了长期干旱对田间条件下植物生长的影响,以及哪些性状可用于区分适应性更强的植物材料。
在两个生长季节对395份不同的红三叶草种质进行了评估。我们使用移动防雨棚在连续两个夏季模拟了6至8周的干旱期,同时在相邻地块建立了一个灌溉对照田。在整个生长季节使用配备RGB和热传感器的无人机进行多次飞行监测植物生长。在整个生长季节的不同观察时刻,我们测量了冠层覆盖度(CC)和冠层高度(CH)。在干旱事件期间或之后不久的两个时刻测定作物水分胁迫指数(CWSI)。
人工测量和无人机测量的CH相关性良好,表明无人机测量结果可可靠地用于红三叶草。在这两年中,CC、CH和CWSI均受到干旱影响,在干旱期结束时以及恢复阶段生长均有明显下降。我们发现干旱处理结束和干旱后约20天的恢复阶段是表型干旱反应和区分基因型的合适时期。
对种质反应的多因素分析揭示了成熟类型与干旱反应之间的相互作用,这表明红三叶草存在两种独立的策略:“耐旱性”和“干旱恢复能力”。我们还发现,在水分充足条件下表现良好的大部分种质受干旱影响也较小。本研究结果结合红三叶草适应干旱育种进展进行了解释。