Root Length Ratio Research Articles

Characteristics of members of IGT family genes in controlling rice root system architecture and tiller development.

Root system architecture (RSA) and tiller are important agronomic traits. However, the mechanisms of the IGT family genes regulate RSA and tiller development in different rice varieties remain unclear. In this study, we demonstrated that 38 rice varieties obtained from Yuanyang Hani’s terraced fields with different RSA and could be classified into six groups based on the ratio of root length and width. We found a positive correlation between RSA (including root width, length, and area) and tiller number in most of rice varieties. Furthermore, the IGT family genes Deeper Rooting 1 (DRO1), LAZY1, TAC1, and qSOR1 showed different expression patterns when rice grown under irrigation and drought conditions. Moreover, the qSOR1 gene had higher levels in the roots and tillers, and accompanied with higher levels of PIN1b gene in roots when rice grown under drought environmental condition. DRO1 gene had two single nucleotide polymorphisms (SNPs) in the exon 3 sequences and showed different expression patterns in the roots and tillers of the 38 rice varieties. Overexpression of DRO1 with a deletion of exon 5 caused shorter root length, less lateral roots and lower levels of LAZY1, TAC1, and qSOR1. Further protein interaction network, microRNA targeting and co-expression analysis showed that DRO1 plays a critical role in the root and tiller development associated with auxin transport. These data suggest that the RSA and tiller development are regulated by the IGT family genes in an intricate network way, which is tightly related to rice genetic background in rice adapting to different environmental conditions.

Alleviation of salt stress in rapeseed (Brassica napus L.) plants by biochar-based rhizobacteria: new insights into the mechanisms regulating nutrient uptake, antioxidant activity, root growth and productivity

ABSTRACT Amendment of saline soils with biochar and rhizobacteria is a new technique to diminish the negative impacts of salt stress on plants. Hence, an original pot experiment was conducted in a glass greenhouse at the University of Tabriz to investigate the performance of salt-stressed (0, 6 and 12 dS m−1 NaCl) rapeseed (Brassica napus L.) plants in response to different biochar-related treatments (non-biochar, biochar, biochar-based Pseudomonas putida RS-198, biochar-based Azotobacter chroococcum RS-106 and both bacteria). The biochar-related treatments reduced sodium content, generation of reactive oxygen species, lipid peroxidation and enzymatic antioxidants in plant tissues while enhanced nutrient content, non-enzymatic antioxidants, main and lateral roots lengths and weights, main/lateral root length ratio, specific root length, root diameter, shoot length and weight, leaf area, chlorophyll content and seed and oil yields under saline conditions. The biochar-based Pseudomonas + Azotobacter was the superior treatment for reducing the harmful impacts of salt stress on rapeseed plants, which resulted in 83–109% and 69–115% improvements in seed and oil yields of this crop under moderate and high salinities, respectively. Therefore, inoculation of biochar with both rhizobacteria might be a novel approach for improving salt tolerance and productivity of rapeseed plants.

Characterizing Root Morphological Traits in 65 Genotypes of Foxtail Millet (Setaria italica L.) from Four Different Ecological Regions in China

As an indispensable grain crop, foxtail millet (Setaria italica L.) is becoming a functional food in China because of its abundant nutrients. However, low rainfall and uneven precipitation limit its growth and production, especially in northwest China. Understanding the root phenotypic characteristics of foxtail millet is critical for utilizing its root characteristics to breed new millet varieties with improved resource-use efficiency and better adaptation to harsh environments. The present study characterized the variability of the root morphological traits at the seedling stage of 65 millet genotypes selected from four ecological regions across seven provinces in China. The plants were assessed after 21 days of growth in the germination pouches, and 48 root and shoot traits were measured. The results showed a large variation among the genotypes in the growth and functional traits. Among the measured traits, root dry mass, maximal root length, root surface area, and root tissue density contributed the most to the principal components. Root surface area ratio and root volume ratio were significantly correlated with root length ratio, respectively, while root length density and root weight density were negatively correlated with root diameter (p < 0.01). Shoot dry mass, root number, root length, root dry mass, and total dry mass were closely correlated with each other. Root length and root surface area in each 5-cm sections decreased from the top to the bottom along the root system. Among the four ecological regions, genotypes from the early maturing area of northwest China had the greatest root length, shoot dry mass, root dry mass, and root density, while those from the early maturing area of northwest China generally had the largest root system, with about 2.2 times more root length and dry weight than those from the early maturing area of northeast China (the shortest root system). The genotypic variability in root traits and correlations among shoot and root traits form a basis for breeding new millet cultivars.

The involvement of abscisic acid-insensitive mutants in low phosphate stress responses during rhizosphere acidification, anthocyanin accumulation and Pi homeostasis in Arabidopsis

Phosphorus is an essential plant nutrient, used in the formation of macromolecules such as nucleic acids and phospholipids. Abscisic acid (ABA) may be involved in the process of low inorganic phosphate (Pi) responses. The phenotypes of ABA-insensitive Arabidopsis mutants (abi1/2/3/4/5) under low Pi stress were investigated to identify possible low Pi response mutant genes. The results showed enhanced rhizosphere acidification in the abi1–1/abi2–1/abi5–1 mutants under low Pi stress compared with wild-type (WT) seedlings. The abi1–1/abi2–1/ abi3–1/abi5–1 mutants accumulated less anthocyanin than the WT, while the abi4–1 mutant showed greater accumulation, implicating all the ABA-insensitive mutants in anthocyanin deposition under Pi deficiency. Alterations in the Pi contents of roots or shoots were also observed in the mutants in response to both Pi sufficiency and deficiency, indicating that the mutants were involved in Pi uptake or transportation. The primary root length and root-shoot ratio of abi3–1 and abi4–1 mutants decreased compared with WT seedlings under low Pi condition. Further research showed that ABI5 could regulate PHT1;5 and WRKY42 expression by combining with ACGT cis-acting elements of the PHT1;5 and WRKY42 promoters.

Biodegradable chelant-metal complexes enhance cadmium phytoextraction efficiency of Solanum americanum.

Toxic contaminants (metals and metal-containing compounds) are accumulating in the environment at an astonishing rate and jeopardize human health. Remarkable industrial revolution and the spectacular economic growth are the prime causes for the release of such toxic contaminants in the environment. Cadmium (Cd) is ranked the 7th most toxic compound by the Agency for Toxic Substances and Disease Registry (USA), owing to its high carcinogenicity and non-biodegradability even at miniscule concentration. The present study assessed the efficiency of four biodegradable chelants [nitrilotriacetic acid (NTA), ethylenediamine disuccinate (EDDS), ethylene glycol tetraacetic acid (EGTA), and citric acid (CA)] and their dose (5mM and 10mM) in enhancing metal accumulation in Solanum americanum Mill. (grown under 24mg Cd kg-1 soil) through morpho-physiological and metal extraction parameters. Significant variations were observed for most of the studied parameters in response to chelants and their doses. However, ratio of root and shoot length, and plant height stress tolerance index differed non-significantly. The potential of chelants to enhance Cd removal efficiency was in the order - EGTA (7.44%) > EDDS (6.05%) > NTA (4.12%) > CA (2.75%). EGTA and EDDS exhibited dose-dependent behavior for Cd extraction with 10mM dose being more efficient than 5mM dose. Structural equation model (SEM) depicted strong positive interaction of metal extraction parameters with chelants (Z-value = 11.61, p = 0.001). This study provides insights into the importance of selecting appropriate dose of biodegradable chelants for Cd extraction, as high chelant concentration might also result in phytotoxicity. In the future, phytoextraction potential of these chelants needs to be examined through field studies under natural environmental conditions.

Effects of groundwater depth on functional traits of young Haloxylon ammodendron.

Groundwater is an important water source for phreatophytic shrubs in arid desert areas. In order to understand the impacts of groundwater depth on functional traits of phreatophytic shrubs, two groups of groundwater levels (2 and 3.5 m) were set up using lysimeter with automatic water replenishing instrument. We measured hydraulic traits, gas exchange characteristics, and root morphological parameters of young Haloxylon ammodendron during the growing season. The results showed that predawn assimilating branch water potential, osmotic potential at full turgor, and root length ratio of young H. ammodendron in the groundwater depth of 3.5 m were lower by 48.2%, 41.5% and 56.7% than that under groundwater depth of 2 m, respectively, while maximum net photosynthetic rate of late growing season, root volume, specific root length and specific root area of fine root were 75.7%, 41.0%, 273.7% and 67.7% higher, respectively. Midday water potential and water content of assimilating branch tended to decrease first in the early growing season and then increase in the late growing season. Root distribution of young H. ammodendron along soil profile showed a significant positive correlation between the average root diameter and soil depth, while the proportion of fine root surface area showed a significant negative correlation with soil depth at both groundwater levels. There was synergy of aboveground assimilating branch hydraulic traits and photosynthetic capacity with belowground root morphological traits in young H. ammodendron. Under the condition of increasing groundwater depth, young H. ammodendron adopted the ecological strategies of reducing predawn assimilating branch water potential and osmotic potential at full turgor, and increasing root diameter and length to enhance water deficit tolerance and expanding the area of water uptake to sustain their survival.

Effects of Solar Radiation on Dry Matter Distribution and Root Morphology of High Yielding Maize Cultivars

The root system connects the plant with the soil, which is a key factor in determining the utilization of soil resources and plant growth potential. Solar radiation can change maize shoot and root growth and affect grain formation. In this study, the effects of different solar radiation conditions on root morphology of three maize cultivars XY335, ZD958 and DH618 and their quantitative relationships were studied by conducting shading experiments. This study was conducted in maize high yield region of Qitai and Yinchuan, China, in 2018 and 2019. The planting densities were 7.5 × 104 (D1) and 12 × 104 (D2) plants ha−1. The shading levels were natural light (CK), shading 15% (S1), 30% (S2) and 50% (S3). The results showed that maize responded to the decreased solar radiation through the increase in ratio of shoot dry weight (SWR) to whole plant dry weight and the decrease in ratio of root dry weight (RWR) to whole plant dry weight. As the solar radiation decreased, the root length density (RLD), root surface area (RSA), average root diameter (ARD) and root length ratio (RLR) decreased, while the specific root length (SRL) increased. With 100 MJ m−2 decrease in solar radiation, the RWR, RLD, RSA and RLR each decreased by 1.47%, 0.5 mm cm−3,0.4 m m−2 and 0. 19 m g−1, respectively. Among the cultivars, the changes of DH618 were the fastest followed by XY335 and ZD958 but DH618 maintained the largest root system under any solar radiation condition. After the decrease of solar radiation, RWR, RLD and RLR were significantly positively correlated with the yield. This indicated that large root systems were conducive to the rapid response to decreased solar radiation and important for achieving stable and high yield. Maize cultivars with these type of root systems should be recommended to better adapt low solar radiation induced by regional variation or climate change.

Phenotyping and Validation of Root Morphological Traits in Barley (Hordeum vulgare L.)

Barley (Hordeum vulgare L.) is an important cereal crop, but its sustainable production is significantly hampered due to the presence of various edaphic stresses. Understanding the variability in root morphological traits among diverse barley genotypes is critical for selecting those with suitable root traits for breeding new cultivars better adapted to stress environments. Root morphological traits in an early growth stage (30 days after transplanting) in a panel of 189 barley genotypes (mostly advanced breeding lines) were assessed using a semi-hydroponic phenotyping platform followed by a validation experiment of eight genotypes with contrasting root systems in two soils. The phenotyping experiment showed large variation (coefficient of variation values ≥ 0.25) in 16 of 26 measured root and shoot traits. A strong correlation among most of the selected traits was identified. Principal component analysis indicated four principal components (eigenvalues >1) captured 79.5% of the total variation. Root traits, including total root length, root length at various depths, root diameter and root length ratio (top 20 cm vs. lower section), could be considered in the barley breeding programs. Consistent ranking of the selected eight genotypes based on root biomass and root length in both the semi-hydroponic system and the columns with two different soils confirmed root trait performance in different growth environments as well as the reliability of the phenotyping method. This study identified phenotypic variability in root morphological traits in barley genotypes in the early growth stage. The genotypic variability in root traits represents a basis for mapping quantitative trait loci (QTLs) and molecular markers, particularly focused on breeding lines with optimal root properties for the efficient acquisition of soil resources and adaptation to drought and other abiotic stresses.

Conservation tillage and nutrient management practices in summer rice (Oryza sativa L.) favoured root growth and phenotypic plasticity of succeeding winter pea (Pisum sativumL.) under eastern Himalayas, India

Low soil moisture during dry season, poor soil properties and lack of adequate crop varieties are the major constraints for sustainable intensification of eastern Himalayas in changing climate. Suitable varieties, tillage alteration and integrated nutrient management with emphasis on locally available crop residues/plant biomass may help addressing these issues. The role of minimum tillage (MT) and no-till (NT), and organic matter substitution on conferring of favourable root environment, improvement in morpho-physiology and subsequent productivity of the crops are not objectively studied in Himalayan ecosystems. Thus, a six year field study was conducted for examining the residual effect of tillage and nutrient management (NM) practices applied to summer (rainy) rice (Oryza sativa L) on root growth-attributes and impact on morpho-physiology of succeeding winter pea (Pisums ativum L.) grown uniformly under NT. Higher root surface area, total root length, root volume, root length ratio (RLR) and root tissue densityin pea crop were observed under residual effect of conventional tillage (CT) relative to NT and MT. In addition, significantly higher values of functional root traits viz., root length ratio (RLR), root mass ratio and root finenessin pea were observed under CT and application of 50% NPK and 100% NPK relative to other tillage and NM practices. However, increased root exudation was observed under NT and MTalong with organic residue addition. Noticeable changes in stress responsive morpho-physiological traits like enhanced chlorophyll pigmentation and favourable leaf characteristics were observed in pea crop grown under NT with 50% NPK+weed biomass (WB)/green leaf manure (GLM) applications. Higher leaf area expansion and thickness were recorded with optimum turgidity under NT and MT than that under CT. Comparative increase in green pod and stover yield of pea with enhanced partition efficiency and harvest index were recorded under MT/NT along with 50% NPK+WB/GLM application than that under CT and other NM practices. Thus, adoption of MT/NT along with 50% NPK+WB/GLM in summer rice is recommended for inducing favourable root environment and optimised pea production in succeeding winter season in study region of the Eastern Himalayas, India and other similar agro-ecosystems.

Identification and characterization of novel QTL conferring internal detoxification of aluminium in soybean.

Aluminium (Al) toxicity inhibits soybean root growth, leading to insufficient water and nutrient uptake. Two soybean lines ('Magellan' and PI 567731) were identified differing in Al tolerance, as determined by primary root length ratio, total root length ratio, and root tip number ratio under Al stress. Serious root necrosis was observed in PI 567731, but not in Magellan under Al stress. An F8 recombinant inbred line population derived from a cross between Magellan and PI 567731 was used to map the quantitative trait loci (QTL) for Al tolerance. Three QTL on chromosomes 3, 13, and 20, with tolerant alleles from Magellan, were identified. qAl_Gm13 and qAl_Gm20 explained large phenotypic variations (13-27%) and helped maintain root elongation and initiation under Al stress. In addition, qAl_Gm13 and qAl_Gm20 were confirmed in near-isogenic backgrounds and were identified to epistatically regulate Al tolerance via internal detoxification instead of Al3+ exclusion. Phylogenetic and pedigree analysis identified the tolerant alleles of both loci derived from the US ancestral line, A.K.[FC30761], originally from China. Our results provide novel genetic resources for breeding Al-tolerant soybean and suggest that internal detoxification contributes to soybean tolerance to excessive soil Al.

Biomass Allocation and Root Characteristics of Early-Stage Poplars (Populus spp.) for Assessing Their Water-Deficit Response During SRC Establishment

Early above- and belowground biomass fractionation, root diameter composition and allocation of cumulated fine root length per total leaf area of Populus clones have been measured for a pre-assessment of the risk for plantation establishment during spring drought conditions. Four clones of Populus × euramericana, and one P. nigra × P. maximowiczii clone (cv. Max 3), were planted in sandy mix substrate and were exposed to one normal and one deficit watering regime over 65-day greenhouse experiments conducted during early summer. The P. × euramericana hybrids showed plasticity of their root biomass fractions. Although clone Max 3 was among the productive clones, even under deficit watering, it was not able to respond plastically to deficit watering. It showed no increase in the root biomass fraction and no increase in the ratio of cumulated fine root length per total leaf area. Therefore, the clone Max 3 should not be planted under high risk for spring drought. Planting the investigated P. × euramericana clones under water deficit likely involves a lower risk, but clone differences within this group must be considered. It can be concluded that the water deficit response of biomass allocation to roots and of the ratio of fine root length per unit leaf area is suitable traits to improve drought risk assessments that are based on yield response of poplar clones to drought. Percent plant loss data and the yield at the end of the first SRC rotation will be suitable to verify the present greenhouse assessment.

Root architectural traits of rooted cuttings of two fig cultivars: Treatments with arbuscular mycorrhizal fungi formulation

Many fruit tree species develop symbioses relationships with mycorrhizal fungi by which they improve their efficiency in water and nutrient uptake and, in turn, increase their vegetative growth and productivity, particularly under stressful environments. These benefits origin from the effects that mycorrhizal determined on the root architecture, morphology and physiology. Usually, few attentions has been devoted to the tree root structure and function, especially, in fig plants during their growth phase in the nursery. Recently, several root traits or phenes have been reported as fundamental for the root functions such as the root length ratio (plant’s potential for the exploitation of soil resources); root mass ratio (allocation traits); the root fineness and tissue density (structural traits); the root very fine, fine and coarse (functional traits). Aim of the study was to test the effects of an arbuscular mycorrhizal fungi (AMF) on the root architecture traits of self-rooted cuttings of two fig (Ficus carica L.) cultivars: Dottato and Natalese. The root architecture traits were evaluated by image analysis system (WinRHIZO). Single root traits and rooting architecture models were statistically tested by univariate and multivariate analysis, respectively. This study confirmed that also the Ficus carica was positively responsiveness to the mycorrhizal inoculation but with cultivar-dependent patterns. Further, the fig with coarse root architecture is more responsive to the fungi inoculation and the AMF induced different root architecture models in Natalese and Dottato suggesting diverse root strategies for exploiting the soil resources.

Analysis of genetic variability and character relationship in rice (Oryza sativa L.) seed and seedling traits

Eight rice genotypes with different genetic backgrounds were evaluated for grain length, grain width, grain length width ratio, grain thickness, 1000 grain weight, seed germination percent, shoot length, root length and root shoot ratio. The genetic variance (δ^2 g), phenotypic variance (δ^2 p), phenotypic covariance (PCV), genotypic coefficient of variation (GCV), heritability (h_b^2), genetic advance (GA), genetic advance in percent of mean (GA %) and correlation coefficient were all calculated. The experiment was conducted using a Randomized Block Design with three replications in a controlled environment in the laboratory of Department of Agriculture at Bangabandhu Sheikh Mujibur Rahman Science and Technology University Gopalganj in June 2021. For all of the studied characters, analysis of variance revealed a significant difference in genotypes. PCV values greater than GCV were found in all of the characteristics, indicating that they were influenced by non-additive gene action rather than environmental factors and that selection for improving these traits would be beneficial. The PCV (41.33) and GCV (41.70) estimates for the root shoot ratio were both high, indicating a wide range of variability for the two component characteristics, shoot length and root length. PCV and GCV values were moderate for grain length width ratio, seed germination percent, shoot length, and root length. The PCV and GCV of most grain characters were low. All of the characters had high heritability, ranging from 90.77 percent to 99.81 percent, except for 1000 grain weight (46.91 percent). Seed germination percent (36.03), shoot length (40.03), root length (35.16) and root shoot ratio (35.16) all had high heritability and high genetic advance in percent of mean (79.25). Grain thickness (8.68) and seed germination percent had the lowest GA% (8.71). Grain length with grain length width ratio, grain width with root shoot ratio, 1000 grain weight with grain width, grain thickness, root length and root shoot ratio were all found to have positive and significant correlations in a character association study. At the genotypic level, the highest positive significant correlation was found between 1000 grain weight and root shoot ratio (r_g= 0.908) and grain length and grain width ratio (r_p=0.900). According to genetic variability and correlation analysis, grain length, grain length width ratio, 1000 grain weight, root length and root shoot ratio could be used as selection indices for further improvement of seed and seedling characters of rice genotypes.

SCREENING OF MAIZE (ZEA MAYS L.) INBRED LINES UNDER WATER DEFICIT CONDITIONS

Development of the selection criteria and selection of crop plant genotypes is a crucial and important task of plant breeders. The present study was designed to screen out the drought or water deficit tolerant maize genotypes. Fifty genotypes were taken from maize germplasm restored by the Department of Plant Breeding and Genetics University of Agriculture, Faisalabad, Pakistan. One set of genotypes were grown under 100% field capacity while other set at 50% field capacity in wire house conditions. The significant contrasts were observed in genotypes of various attributes under ordinary and stress timeframe. The traits root length and root shoot ratio by mass showed the high heritability and genetic advance and genotypic correlation with each other under water deficit condition provided the basis for the selection. The principle component analysis showed that the genotypes A545, AES204, WM13RA were chosen on the premise of better performance for most of the traits under study. These lines may be used in further breeding program as candidate parents for the development of drought tolerant hybrids.

The impact of different morphological and biochemical root traits on phosphorus acquisition and seed yield of Brassica napus

Abstract Oilseed rape (Brassica napus L.) is an important crop in China. Although its yields are restricted by phosphorus (P) supply, the response of its root system to P supply has not been explored systematically. This study aimed to investigate the contribution of root morphological and biochemical traits to P acquisition from soils with deficient P (30 kg P2O5 ha−1) and sufficient P (90 kg P2O5 ha−1) supplies in the field at the leaf development, stem elongation, flowering, pod development and ripening stages. The total root length and root surface area in the surface soil (0−10 cm soil layer) were both reduced significantly by decreasing P supply. However, a larger root/shoot ratio and root length ratio were observed in plants with the deficient P supply at the flowering stage. Roots of plants with a deficient P supply also secreted more acid phosphatase and organic acid into the rhizosphere from stem elongation to pod development than plants with a sufficient P supply. Seed yield (SY), shoot dry weight (SDW) and total P content (TPC) were strongly correlated with root morphological traits at the leaf development and flowering stages, especially with the coarse root length (CRL) and root surface area in the surface soil. However, there were no correlations between SDW or TPC and root biochemical traits (rhizosphere pH, acid phosphatase activity and organic acid content). It is hypothesized that greater CRL in the surface soil (0−10 cm soil layer) at the leaf development and flowering stages, served as a scaffold for fine roots, enhancing soil exploration and P acquisition, and, thereby, increasing seed yield.

Root depth development in tropical perennial forage grasses is related to root angle, root diameter and leaf area

Tropical perennial grasses that can rapidly establish deep roots have a greater potential to survive soil surface drying sooner after establishment. This research aimed to identify species that establish deep roots quickly and to investigate the mechanisms that drove rapid vertical root development. Perennial grass species Brachiaria brizantha, Brachiaria decumbens, Brachiaria humidicola, Brachiaria hybrid Mulato II, Brachiaria mosambicensis, Panicum maximum, Setaria sphacelata and Cynodon dactylon were grown in rhizotrons that facilitated measurement of the rate of root depth development, the rate of root length development, photosynthesis and morphological traits. Principal component analysis was employed to separate grass species according to functional traits of vertical root development and their growth strategies. P. maximum established roots more rapidly to 50 cm depth than the other species examined and accumulated biomass and leaf area faster. It was differentiated from other species by a greater percentage of fine root length (< 0.2 mm diameter), a higher photosynthetic rate and ratio of root length to leaf area according to the principal component analysis. The growing degree days required for root establishment to 50 cm depth was negatively correlated with the percentage of fine root length, and positively correlated with root angle. The exponential rate of root depth development per growing degree day increased with average root diameter in B. humidicola and B. hybrid Mulato II, indicating a conservative growth strategy. Rapid vertical root development with a narrow root angle, higher photosynthetic rate, higher ratio of root length to leaf area and higher percentage of fine roots were apparent mechanisms that enabled P. maximum to establish deep roots faster than other species. P. maximum appears to be better able to avoid water stress during surface drying by accessing profile moisture. Greater average root diameter and percentage of root length with higher diameters was related to increased exponential rate of root depth development and wide root angle.

Genotypic Variability in Some Morpho-Physiological Traits in Different Environments and Their Relationship with Cassava (Manihot esculentaCrantz) Root Yield

Cassava root yield under diverse environments is influenced by morpho-physiological traits that are in turn influenced by genotype, environment, and genotype × environment interaction (GEI). Most GEI analyses in cassava have been limited to root yield with less emphasis on stability of other yield-related traits. This study was carried out to assess the effect of GEI on some morpho-physiological traits in cassava and key traits that are useful for selection in different environments. The study utilized 20 cassava genotypes evaluated in six environments, namely, Fumesua 2013 and 2014, Nyankpala 2013 and 2014 (irrigation), and Nyankpala 2013 and 2014 (no irrigation). The genotypes were arranged in a randomized complete block design (RCBD) with three replications and assessed for a number of morpho-physiological traits, root yield and yield components. The data were subjected to analysis of variance using SAS statistical package. Subsequently, the GGE biplot was used to carry out genotype × environment, genotype × trait, and environment × trait interaction analyses to determine the specificity of genotypic performance and traits linked to particular environments. The results indicated significant (P&lt;0.05) GEI effect on all traits except leaf temperature. The genotype × trait biplot analysis revealed closely related traits and those associated with root yield and genotypes that show weakness in these traits. Both environment × trait biplot and principal component analyses identified traits with higher discriminatory power among genotypes in various environments particularly in the dry environments. These can be used as secondary traits to select drought-tolerant genotypes. From this study, the GGE biplot was useful in identifying traits associated with specific genotypes in different environments to aid in selection. Moderate broad-sense heritability estimates werefound for storage root yield, harvest index, plant height, ratio of storage rootlength to girth, and cassava mosaic disease score indicating that progresscan be made through selection for these traits.

In vitro screening of chickpea genotypes for drought related traits using PEG 6000

Chickpea is adversely affected by drought stress at all the growth stages including germination and seedling emergence thereby seedling establishment. An in vitro screening method was used to screen the genotypes for drought tolerance using polyethylene glycol (PEG) 6000. Six drought related seedling traits viz. germination percentage, shoot length (cm), root length (cm), shoot-root ratio, number of secondary roots and relative water content were studied in fifteen genotypes including thirteen MAGIC lines and two varieties JG 11 and HC 5. PEG solutions of 3%, 5% and 7% were used to induce different levels of water stress to compare with control (0%). Analysis of variance revealed significant variability among genotypes, different levels of PEG as well as between genotypes and stress levels. In general a decrease in the mean values under subsequent water induced stress was observed as compared to control in all the six traits under study with few exceptions like root length and shoot root ratio. The root of few genotypes viz. M 31, JG 11, HC 5, M 30 and M 27 increased with increase in stress level. Similarly, shoot root ratio also increased in two genotypes namely M 37 and M 32. Considering complex and quantitative nature of drought tolerance, drought related traits were assigned rank score given to each genotype in order of showing increase or minimum decrease in that seedling trait at control and 7% PEG induced stress levels. Total sum of scores over six seedling parameters revealed that JG 11 was most drought tolerant among all fifteen genotypes under study with total score of seventy six, followed by HC 5 whereas M33 was the most susceptible genotype for drought tolerance.

Ornamental plants for floating treatment wetlands: preliminary results

Floating treatment wetlands (FTWs) represent a novel ecotechnology for the treatment of different types of wastewaters in natural or artificial water bodies, through the use of traditional rooted emergent macrophyte species supported by floating rafts. Although many studies have reported the treatment performances of FTWs, showing an excellent aptitude for removing nutrients, heavy metals as well as suspended solids, the investigation of vegetation has not received much attention up to now, especially for herbaceous ornamental plant species that could form an interesting opportunity to improve water quality and the esthetic-ornamental value of urban water bodies. For this reason, a pilot scale FTW was installed in Northern Italy to assess the growth performances of eleven wetland species having ornamental features: Canna indica L., Pontederia cordata L., Thalia dealbata Fraser ex Roscoe, Acorus calamus L., Juncus effusus L., Iris laevigata L., Mentha aquatica L., Oenanthe javanica (Blume) DC., Caltha palustris L., Sparganium erectum L. and Zantedeschia aetiopica (L.) Srengel. For these species, a suitability index was elaborated that considers plant survivability, above-mat biomass production, nitrogen uptake, root length and root-shoot ratio. On this basis, the results obtained clearly indicated that C. indica, P. cordata and T. dealbata were the most suitable species for FTW due to their high vigor and colonization of the floating mats (1638.9 g m–2, 483.4 g m–2, 566.1 g m–2 of above-mat dry biomass, respectively; 38.8 cm, 62.0 cm, 43.8 cm root length, respectively; 0.8, 0.9, 1.2 root-shoot ratio, respectively), survival (100%), nitrogen uptake (15.1 g m–2, 15.0 g m–2, 15.7 g m–2 respectively). On the contrary, A. calamus, S. erectum and Z. aetiopica did not present adequate features for use in FTWs.

Effect of irrigation scheduling and live mulching of cowpea on root characteristics, consumptive use and water use efficiency of upland rice

The field experiment was conducted in the farmer's field, Peringammala, Kalliyoor, Thiruvananthapuram during the Virippu 2017 to study the effect of irrigation scheduling and live mulching with cowpea on root and soil moisture characteristics of upland rice. The results revealed that root characters like root volume, root dry weight and root shoot ratio significantly increased under the irrigation treatment I1 [irrigation at 3 cm depth at 10 mm cumulative pan evaporation (CPE)]. The root length was the highest for rain fed control (I7). Among the mulches, live mulching with cowpea (M2) recorded the highest root length and root shoot ratio. The treatments and their interaction had a significant influence on soil moisture. Irrigation at 3 cm depth at 10 mm CPE, live mulching with cowpea and their interaction recorded the highest consumptive use. The highest water use efficiency was recorded by the treatment irrigation at 2 cm depth at 20 mm CPE (I5) and live mulching with cowpea (M2).