Adu Michael Osei, Asare Paul Agu, Asare-Bediako Elvis, Amenorpe Godwin, Ackah Frank Kwekucher, Afutu Emmanuel, Amoah Mishael Nyarko, Yawson David Oscar
Department of Crop Science, School of Agriculture, College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana.
Nuclear Agricultural Research, Biotechnology and Nuclear Agriculture Research Institute, Ghana Atomic Energy Commission, Legon, Accra, Ghana.
Heliyon. 2018 Jun 28;4(6):e00665. doi: 10.1016/j.heliyon.2018.e00665. eCollection 2018 Jun.
The development of cassava genotypes with root system traits that increase soil resource acquisition could increase yields on infertile soils but there are relatively few work that has quantified cassava root system architecture (RSA). We used an easily adaptable and inexpensive protocol to: (i) measure genotypic variation for RSA and shoot traits of a range of cassava genotypes; and (ii) identify candidate variables that contribute the largest share of variance. Cassava genotypes were grown in soil-filled pots, maintained at 70% field capacity. Shoot and RSA traits were measured on plants grown up to 30, 45 and 60 days. Multivariate analysis was used to determine major traits contributing to variation. The study showed that cassava roots are adventitious in origin consisting of a main root axis and orders of lateral roots, and therefore the historically used term "fibrous roots" are redundant currently not contributing to clarity. There were significant differences ( < 0.05) for traits evaluated. The highest relative root growth rate occurred over the first 30 days and ranged from 0.39 to 0.48 cm day. Root fresh weight was significantly correlated with other traits, including root length ( = 0.79), leaf area ( = 0.72), number of lower nodal roots ( = 0.60), indicating that direct selection based on these traits might be sufficient to improve root biomass. Up to the first six principal components explained over 80% of the total variation among the genotypes for the traits measured at 30, 45 and 60 days. Leaf area, root diameter and branching density-related traits were the most important traits contributing to variation. Selection of cassava genotypes based on shoot and root biomass, root diameter and branching density at juvenile growth stage could be successful predictors of nutrient and water-use efficiency in the field. Further studies are required to relate studied juvenile cassava root traits with the performance of field-grown-mature plant with regard to drought, nutrient-use efficiency and yield.
培育具有能增加土壤资源获取的根系性状的木薯基因型，可提高贫瘠土壤上的产量，但量化木薯根系结构（RSA）的研究相对较少。我们采用了一种易于调整且成本低廉的方案来：（i）测量一系列木薯基因型的RSA和地上部性状的基因型变异；（ii）识别贡献最大变异份额的候选变量。木薯基因型种植在装满土壤的花盆中，保持在田间持水量的70%。在生长至30、45和60天的植株上测量地上部和RSA性状。采用多变量分析来确定导致变异的主要性状。研究表明，木薯根起源于不定根，由一个主根轴和各级侧根组成，因此历史上使用的术语“须根”目前是多余的，无助于清晰表达。所评估的性状存在显著差异（<0.05）。最高相对根生长速率出现在最初30天内，范围为0.39至0.48厘米/天。根鲜重与其他性状显著相关，包括根长（=0.79）、叶面积（=0.72）、下部节根数量（=0.60），这表明基于这些性状的直接选择可能足以提高根生物量。前六个主成分解释了在30、45和60天测量的性状中基因型间总变异的80%以上。叶面积、根直径和与分支密度相关的性状是导致变异的最重要性状。在幼龄生长阶段基于地上部和根生物量、根直径和分支密度选择木薯基因型，可能是田间养分和水分利用效率的成功预测指标。需要进一步研究将所研究的木薯幼根性状与田间成熟植株在干旱、养分利用效率和产量方面的表现联系起来。
