Plant Roots and Their Environment

Plant Roots and Their Environment
Author: B.L. McMichael
Publisher: Elsevier
Total Pages: 662
Release: 2012-12-02
Genre: Science
ISBN: 0444598421
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Scientists, within a wide field, ranging from applied forestry and agriculture to physiology, ecology and the environmental sciences, are today more than ever involved in root and mycorrhizal research. New problem-oriented research fields have arisen such as the effects of fertilizers and pesticides, forest management and regeneration etc. At a time when root research is expanding into different areas, it is much more difficult for the root scientist to penetrate all the new information appearing in literature. The contributors of this volume are leading scientists from different fields of root research. The ISRR-symposium in Uppsala clearly demonstrated that there are new techniques in progress, in particular with regards to video recording of plant root systems and digital image processing. The main objectives of the symposium were (i) to provide a forum for communication between scientists from different disciplines working with root research problems, (ii) to contribute to an expansion of root studies into new areas, (iii) to use current estimates of root turnover for charting the upper and lower limit of below-ground production, and (iv) to spread knowledge of new findings and techniques of the importance of root research. This book is aimed at serving as a vehicle for improving the coherence of root research, for harmonizing methods and establishing overall objectives and gaps in the knowledge of rhizosphere dynamics.

Quantitative Trait Locus (QTL) Mapping of Transpiration Efficiency Related to Pre-flower Drought Tolerance in Sorghum [Sorghum Bicolor (L.) Moench]

Quantitative Trait Locus (QTL) Mapping of Transpiration Efficiency Related to Pre-flower Drought Tolerance in Sorghum [Sorghum Bicolor (L.) Moench]
Author: Mohankumar Heraganahally Kapanigowda
Publisher:
Total Pages:
Release: 2012
Genre:
ISBN:
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There is an increasing need to improve crop water-use efficiency (WUE) (ratio of whole-plant biomass to cumulative transpiration) due to decreased water availability and increased food and energy demands throughout the world. The objective of the study was to estimate the genetic variation and genetic basis for transpiration efficiency A:E (CO2 assimilation rate (A) divided by transpiration rate (E)) trait and its relationship to WUE related to pre-flower drought tolerance in recombinant inbred lines (RILs) of sorghum and associated QTLs. A greenhouse study was conducted at Bushland, TX, 2008, using 71 RILs derived from cross of Tx430 x Tx7078. A randomized complete block experimental design was used, with both genotype and water regime (40 and 80 percent water regime) as experimental factors, and four replications. Genotype had a significant effect on A, E and A:E under both the environments. Among the RILs, entry means for A:E ranged from 1.58 to 3.07 mmol CO2 mol^-1 H2O and 1.18 to 4.36 mmol CO2 mol^-1 H2O under 80 percent and 40 percent water regime, respectively. Heritability estimates based on individual environments for A:E, A and E were 0.77, 0.45 and 0.37 under 80 percent water regime and 0.90, 0.33 and 0.71 under 40 percent water regime, respectively. A genetic map was constructed by digital genotyping method using Illumina GAII sequencer with 261 informative indel/ single-nucleotide polymorphism (SNP's) markers distributed over 10 linkage groups. Three significant QTLs associated with transpiration efficiency were identified; two on SBI-09 and one on SBI-10 with one logarithmic of odds (LOD) interval length ranging from 5.3 to 5.7 cM and accounting for 17 percent - 21 percent of the phenotypic variation. In field and greenhouse evaluation of agronomic of traits at College Station and Halfway, TX, 91 QTL that control variation in six major agronomic traits such as plant height, flowering, biomass, leaf area, leaf greenness and stomatal density were identified. Co-localization of transpiration efficiency QTLs with agronomic traits such as leaf area, biomass, leaf width and stomatal density indicated that these agronomically important QTLs can be used for further improving the sorghum performance through marker assisted selection (MAS) under pre-flowering drought stress conditions.