Haling Rebecca E, Brown Lawrie K, Bengough A Glyn, Valentine Tracy A, White Philip J, Young Iain M, George Timothy S
School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia,
Planta. 2014 Mar;239(3):643-51. doi: 10.1007/s00425-013-2002-1. Epub 2013 Dec 8.
Selecting plants with improved root hair growth is a key strategy for improving phosphorus-uptake efficiency in agriculture. While significant inter- and intra-specific variation is reported for root hair length, it is not known whether these phenotypic differences are exhibited under conditions that are known to affect root hair elongation. This work investigates the effect of soil strength, soil water content (SWC) and soil particle size (SPS) on the root hair length of different root hair genotypes of barley. The root hair and rhizosheath development of five root hair genotypes of barley (Hordeum vulgare L.) was compared in soils with penetrometer resistances ranging from 0.03 to 4.45 MPa (dry bulk densities 1.2-1.7 g cm(-3)). A "short" (SRH) and "long" root hair (LRH) genotype was selected to further investigate whether differentiation of these genotypes was related to SWC or SPS when grown in washed graded sand. In low-strength soil (<1.43 MPa), root hairs of the LRH genotype were on average 25 % longer than that of the SRH genotype. In high-strength soil, root hair length of the LRH genotype was shorter than that in low-strength soil and did not differ from that of the SRH genotype. Root hairs were shorter in wetter soils or soils with smaller particles, and again SRH and LRH did not differ in hair length. Longer root hairs were generally, but not always, associated with larger rhizosheaths, suggesting that mucilage adhesion was also important. The root hair growth of barley was found to be highly responsive to soil properties and this impacted on the expression of phenotypic differences in root hair length. While root hairs are an important trait for phosphorus acquisition in dense soils, the results highlight the importance of selecting multiple and potentially robust root traits to improve resource acquisition in agricultural systems.
选择具有改善的根毛生长的植物是提高农业中磷吸收效率的关键策略。虽然根毛长度存在显著的种间和种内差异，但尚不清楚这些表型差异是否在已知影响根毛伸长的条件下表现出来。这项工作研究了土壤强度、土壤含水量（SWC）和土壤颗粒大小（SPS）对大麦不同根毛基因型根毛长度的影响。在穿透阻力范围为0.03至4.45 MPa（干容重1.2 - 1.7 g cm(-3)）的土壤中，比较了大麦（Hordeum vulgare L.）五种根毛基因型的根毛和根际鞘发育情况。选择了一个“短”（SRH）根毛基因型和一个“长”根毛（LRH）基因型，以进一步研究这些基因型在水洗分级砂中生长时的分化是否与SWC或SPS有关。在低强度土壤（<1.43 MPa）中，LRH基因型的根毛平均比SRH基因型长25%。在高强度土壤中，LRH基因型的根毛长度比低强度土壤中的短，且与SRH基因型的根毛长度没有差异。在较湿润的土壤或颗粒较小的土壤中根毛较短，并且SRH和LRH的根毛长度再次没有差异。较长的根毛通常（但并非总是）与较大的根际鞘相关，这表明粘液粘附也很重要。发现大麦的根毛生长对土壤性质高度敏感，这影响了根毛长度表型差异的表达。虽然根毛是在致密土壤中获取磷的重要性状，但结果突出了选择多种且可能稳健的根性状以改善农业系统中资源获取的重要性。
