Root Systems Of Crop Plants Research Articles

Plasticity of root hair and rhizosheath traits and their relationship to phosphorus uptake in sorghum.

Sorghum is an essential crop for resilient and adaptive responses to climate change. The root systems of crop plants significantly contribute to the tolerance of abiotic stresses. There is little information on sorghum genotypes' root systems and plasticity to external P supply. In this paper, we investigated the variations in root systems, as well as the responses, trait relationships, and plasticity of two sorghum genotypes (Naga Red and Naga White), popularly grown in Ghana, to five external P concentrations ([P]ext): 0, 100, 200, 300, and 400 mg P kg-1 soil. Sorghum plants were grown in greenhouse pots and harvested for root trait measurements at the five-leaf and growing point differentiation (GPD) developmental stages. The plants were responsive to [P]ext and formed rhizosheaths. The two genotypes showed similar characteristics for most of the traits measured but differed significantly in total and lateral root lengths in favor of the red genotype. For example, at the five-leaf growth stage, the lateral root length of the red and white genotypes was 22.8 and 16.2cm, respectively, but 124 and 88.9cm, at the GPD stage. The responses and plasticity of the root system traits, including rhizosheath, to [P]ext were more prominent, positive, and linear at the five-leaf stage than at the GPD growth stage. At the five-leaf growth stage, total root length increased by about 2.5-fold with increasing [P]ext compared to the unamended soil. At the GPD stage, however, total root length decreased by about 1.83-fold as [P]ext increased compared to the unamended soil. Specific rhizosheath weight correlated with RHD, albeit weakly, and together explained up to 59% of the variation in tissue P. Root hair density was more responsive to P supply than root hair length and showed a similar total and lateral root length pattern. Most desirable responses to P occurred at a rate of 200-300 mg P kg-1 soil. It is concluded that sorghum would form rhizosheath, and [P]ext could be critical for the early vigorous growth of sorghum's responsive root and shoot traits. Beyond the early days of development, additional P application might be necessary to sustain the responses and plasticity observed during the early growth period, but this requires further investigation, potentially under field conditions.

X-Ray Computed Tomography of Crop Plant Root Systems Grown in Soil.

Non-destructive methods to quantify the root system architecture of a plant grown in soil are essential to aid our understanding of the factors that impact plant root development in natural environments. With environmental change threatening our ability to sustain agricultural productivity for an expanding global population, the application of these methods has never before seen such an increase in demand. X-ray computed tomography (CT) based phenotyping techniques permit the spatio-temporal quantification of roots, helping to identify novel adaptive root architectural responses to abiotic and biotic factors. This protocol reports an integrated workflow from column preparation and plant growth to image and quantification of the root system using novel open source software applications, RooTrak and RooTh. © 2017 by John Wiley & Sons, Inc.

Manipulating lignin deposition

Schuetz, M., Douglas, C., Samuels, L. and Ellis, B. 2014. Manipulating lignin deposition. Can. J. Plant Sci. 94: 1043–1049. Since lignin represents one of most durable forms of fixed carbon in plant biomass, we hypothesized that increasing root lignin content for crops whose root systems remained in the soil after harvest would elevate the total amount of carbon retained in the soil in Canadian agroecosystems. The immediate goal of this Greencrop project was, therefore, to gain a better understanding of the molecular mechanisms that control deposition of the lignin polymer in plant cell walls, with a view to eventually manipulating the quantity and location of lignin in crop plant root systems. To this end, we examined two classes of Arabidopsis thaliana proteins – transcription factors, which are believed to play crucial roles in regulating lignin biosynthesis, and ATP binding cassette transporters, which are putative lignin precursor transporters. These studies revealed that a complex network of interacting transcriptional regulators is involved in activating and suppressing the expression of key genes required for secondary cell wall deposition and lignification.

Manipulating lignin deposition

Schuetz, M., Douglas, C., Samuels, L. and Ellis, B. 2014. Manipulating lignin deposition. Can. J. Plant Sci. 94: 1043-1049. Since lignin represents one of most durable forms of fixed carbon in plant biomass, we hypothesized that increasing root lignin content for crops whose root systems remained in the soil after harvest would elevate the total amount of carbon retained in the soil in Canadian agroecosystems. The immediate goal of this Greencrop project was, therefore, to gain a better understanding of the molecular mechanisms that control deposition of the lignin polymer in plant cell walls, with a view to eventually manipulating the quantity and location of lignin in crop plant root systems. To this end, we examined two classes of Arabidopsis thaliana proteins - transcription factors, which are believed to play crucial roles in regulating lignin biosynthesis, and ATP binding cassette transporters, which are putative lignin precursor transporters. These studies revealed that a complex network of interac...

Not all ALMT1‐type transporters mediate aluminum‐activated organic acid responses: the case of ZmALMT1 – an anion‐selective transporter

The phytotoxic effects of aluminum (Al) on root systems of crop plants constitute a major agricultural problem in many areas of the world. Root exudation of Al-chelating molecules such as low-molecular-weight organic acids has been shown to be an important mechanism of plant Al tolerance/resistance. Differences observed in the physiology and electrophysiology of root function for two maize genotypes with contrasting Al tolerance revealed an association between rates of Al-activated root organic acid release and Al tolerance. Using these genotypes, we cloned ZmALMT1, a maize gene homologous to the wheat ALMT1 and Arabidopsis AtALMT1 genes that have recently been described as encoding functional, Al-activated transporters that play a role in tolerance by mediating Al-activated organic acid exudation in roots. The ZmALMT1 cDNA encodes a 451 amino acid protein containing six transmembrane helices. Transient expression of a ZmALMT1::GFP chimera confirmed that the protein is targeted to the plant cell plasma membrane. We addressed whether ZmALMT1 might underlie the Al-resistance response (i.e. Al-activated citrate exudation) observed in the roots of the Al-tolerant genotype. The physiological, gene expression and functional data from this study confirm that ZmALMT1 is a plasma membrane transporter that is capable of mediating elective anion efflux and influx. However, gene expression data as well as biophysical transport characteristics obtained from Xenopus oocytes expressing ZmALMT1 indicate that this transporter is implicated in the selective transport of anions involved in mineral nutrition and ion homeostasis processes, rather than mediating a specific Al-activated citrate exudation response at the rhizosphere of maize roots.

Studies on pre-treatment of seeds with chemicals I. The effect of presoaking the seed in various chemicals on the growth and yields of paddy

A great deal of attention has been devoted in recent years, towards a more efficient utilisation of fertilizers in crop production. Various methods have been tried, starting from broadcasting, to placement of fertilizers right in the feeding zone of the root systems of crop plants, with the object of making available a larger quantity of nutrients to the growing plants. Amongst the various methods tried, coating the seeds with fertilizers was one; thus Gusev (1940) had claimed that by pretreating seeds with phosphates before sowing, either by moistening the seeds with an aqueous solution of phosphate fertilizer or by smearing the seeds with a mixture of starch paste and fertilizer, the plants were able to utilize as much as 70-80 percent of the phosphate supplied. This idea was taken a step further by Roach and Roberts (1949) in Great Britain, and subsequently other workers had also found there were practical possibilities in this method of seed pre-treatment with chemicals. In India, the Indian Council of Agricultural Research sponsored a research scheme in 1952 to investigate the scope and possibilities of this method, in improving the growth and yields of important crops. This scheme was worked in the Plant Physiology section of the Agricultural Research Institute at Coimbatore, and a number of crop plants was studied; the results obtained in rice (paddy) plants are presented in this paper.