Belachew Kiflemariam Y, Nagel Kerstin A, Poorter Hendrik, Stoddard Frederick L
Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland.
Department of Plant Sciences, Bahir Dar University, Bahir Dar, Ethiopia.
Front Plant Sci. 2019 Sep 4;10:1063. doi: 10.3389/fpls.2019.01063. eCollection 2019.
Water deficit may occur at any stage of plant growth, with any intensity and duration. Phenotypic acclimation and the mechanism of adaptation vary with the evolutionary background of germplasm accessions and their stage of growth. Faba bean is considered sensitive to various kinds of drought. Hence, we conducted a greenhouse experiment in rhizotrons under contrasting watering regimes to explore shoot and root traits and drought avoidance mechanisms in young faba bean plants. Eight accessions were investigated for shoot and root morphological and physiological responses in two watering conditions with four replications. Pre-germinated seedlings were transplanted into rhizotron boxes filled with either air-dried or moist peat. The water-limited plants received 50-ml water at transplanting and another 50-ml water 4 days later, then no water was given until the end of the experimental period, 24 days after transplanting. The well-watered plants received 100 ml of water every 12 h throughout the experimental period. Root, stem, and leaf dry mass, their mass fractions, their dry matter contents, apparent specific root length and density, stomatal conductance, SPAD value, and Fv/Fm were recorded. Water deficit resulted in 3-4-fold reductions in shoot biomass, root biomass, and stomatal conductance along with 1.2-1.4-fold increases in leaf and stem dry matter content and SPAD values. Total dry mass and apparent root length density showed accession by treatment interactions. Accessions DS70622, DS11320, and ILB938/2 shared relatively high values of total dry mass and low values of stomatal conductance under water deficit but differed in root distribution parameters. In both treatments, DS70622 was characterized by finer roots that were distributed in both depth and width, whereas DS11320 and ILB938/2 produced less densely growing, thicker roots. French accession Mélodie/2 was susceptible to drought in the vegetative phase, in contrast to previous results from the flowering phase, showing the importance of timing of drought stress on the measured response. Syrian accession DS70622 explored the maximum root volume and maintained its dry matter production, with the difference from the other accessions being particularly large in the water-limited treatment, so it is a valuable source of traits for avoiding transient drought.
水分亏缺可能在植物生长的任何阶段出现，其强度和持续时间各异。表型适应及适应机制会因种质资源的进化背景及其生长阶段而有所不同。蚕豆被认为对各类干旱较为敏感。因此，我们在根箱中进行了温室试验，设置了不同的浇水制度，以探究蚕豆幼苗地上部和根部的性状以及干旱规避机制。研究了8个种质在两种浇水条件下地上部和根部的形态及生理响应，每种条件重复4次。预先催芽的幼苗被移栽到装满风干泥炭或湿润泥炭的根箱中。水分受限的植株在移栽时浇50毫升水，4天后再浇50毫升水，之后直至试验期结束（移栽后24天）不再浇水。水分充足的植株在整个试验期内每12小时浇100毫升水。记录了根干质量、茎干质量、叶干质量、它们的质量分数、干物质含量、表观比根长和根密度、气孔导度、SPAD值以及Fv/Fm。水分亏缺导致地上部生物量、根生物量和气孔导度降低3 - 4倍，同时叶和茎干物质含量以及SPAD值增加1.2 - 1.4倍。总干质量和表观根长密度表现出种质与处理的交互作用。种质DS70622、DS11320和ILB938/2在水分亏缺条件下总干质量相对较高，气孔导度较低，但根分布参数不同。在两种处理中，DS70622的特点是根系较细，分布在深度和宽度上，而DS11320和ILB938/2的根系生长密度较小、较粗。法国种质Mélodie/2在营养生长期易受干旱影响，这与之前在开花期的结果相反，表明干旱胁迫的时间对所测响应具有重要影响。叙利亚种质DS70622探索了最大的根体积并维持其干物质生产，在水分受限处理中与其他种质的差异尤为显著，因此它是避免短期干旱性状的宝贵来源。
