Root Length Ratio Research Articles

Impact of Melatonin Application on Wheat Agronomic Traits Under Abiotic Stress: A Meta‐Analysis

ABSTRACTThis meta‐analysis assesses the effects of melatonin (Mel) on various wheat agronomic traits, revealing significant heterogeneity and potential publication bias. This comprehensive analysis highlights the variability across studies (I2 > 98% for overall, leaf area, root and shoot weight), indicating a potential for selective reporting in the analysed studies. Grain yield and root weight showed I2 values of 93.78% and 99.54%, respectively, confirming the complex nature of melatonin's impact, which necessitates the use of random‐effects models. Notably, the study uncovers significant heterogeneity in wheat traits (p < 0.05). Mel increased grain yield by 33.50% and positively influenced root and shoot weights compared to control (no melatonin; nMel). However, the effects varied across different Mel concentration, application method and environmental stressors. Grain yield significantly increased with Mel application, particularly in foliar spray by 41.40%, compared to nMel. Mel consistently enhanced the overall response ratio (lnRR) of grain yield, grain weight, root length, shoot length, leaf area, plant height, shoot weight and root weight by 33.50%, 24.01%, 21.28%, 32.99%, 36.33%, 15.94%, 22.14% and 20.86% compared to nMel. Compared to nMel, the most pronounced grain yield was observed in Mel under salt stress conditions. The benefits of Mel were more pronounced in Egypt, where grain yield increased by 52.91%, suggesting that local environmental factors significantly influence its efficacy. Its impact varied across different cultivars, with Jimai_22 increased root length by 70.83% and Sids_14 by 56.39% compared to nMel, emphasising the importance of genetic factors. Mel application under salt and Cd stress conditions increased root weight by 336% and 470%, respectively, while decreased by 87% under waterlogging compared to no stress conditions. This indicates that Mel greatly increased plant resistance to abiotic stresses by modulating stress‐responsive pathways and improving agronomic traits.

Relationship between root characteristics and saturated hydraulic conductivity in a grassed clayey soil

Soil saturated hydraulic conductivity plays a crucial role in the fields of hydrology, geotechnical and geological engineering. This study investigated the relationship between root characteristics and soil saturated hydraulic conductivity in a grassed soil. The saturated hydraulic conductivity of soil specimens with varying soil dry densities and planting densities were experimentally determined. Root parameters of each specimen were measured, and the relationship between root parameters and soil saturated hydraulic conductivity was determined through the stepwise multiple regression analysis. Experimental results show that both soil dry density and planting density significantly influence root growth and the saturated hydraulic conductivity of the grassed soil. Root length ratio (>4 cm), root length, and root weight density exhibit a positive correlation with planting density, while root length density and root length ratio (>4 cm) are negatively correlated with dry density. Higher dry density leads to lower soil saturated hydraulic conductivity and the permeable effects become more pronounced with increased planting density. When planting density is higher, roots create more preferential flow channels in the soil, resulting in increased soil saturated hydraulic conductivity. Root length density exerts the most significant effect on soil saturated hydraulic conductivity (|r| = 0.82, p＜0.01), followed by root length ratio (>4 cm) and root weight density. This study provides insights into the relationship between root parameters and soil saturated hydraulic conductivity, and identifies key root parameters that govern the saturated hydraulic conductivity of soil. These findings hold significant implications for enhancing the understanding of slope protection using vegetation.

Root morphology parameters and nutrient acquisition capabilities of grafted tomato plants in root-restricted conditions are subject to salinity and rootstock characteristics

ABSTRACT A tomato cultivar ('Izmir F1') grafted onto six commercially available rootstocks ('Arnold', 'Dohkko', 'Emperador', 'He-man', 'Kaiser', and 'Suzuka') together with self-grafted plants of the tomato cultivar (Izmir/Izmir) were included in a pot experiment. Growth, root morphology and nutrient uptake parameters were evaluated under different salinity conditions (0 and 50 mM NaCl). Grafting increases root length, specific root length, and root length ratio, which enhances the capabilities of hetero-grafted plants to exploit a larger volume of soil or otherwise increase root density under root restriction conditions. Since the root traits and nutrient concentrations in hetero-grafted variants were less impacted by a change in the salinity level, the use of specific rootstocks (‘Arnold,’ ‘Dohkko,’ ‘Kaiser’) could contribute to a steadier growth and yield of tomato plants under fluctuating salinity levels in the irrigation water. The hetero-grafted tomato plants (Dohkko/Izmir, Suzuka/Izmir) demonstrated higher Na sequestration/compartmentalization capabilities than the self-grafted (Izmir/Izmir) plants which helps to maintain a more appropriate K+/Na+ ratio. By exhibiting lower translocation indexes of some heavy metals (Al, Ni, Zn, and Cd), appropriate rootstock/scion combinations might be a useful tool for reducing the risk of their accumulation in edible plant organs.

NaHS immersion alleviates the stress effect of chromium(III) on alfalfa seeds by affecting active oxygen metabolism

ABSTRACT Objective This study aimed to investigate the regulatory effects of exogenous hydrogen sulfide (H2S) on seed germination, seedling growth, and reactive oxygen species (ROS) homeostasis in alfalfa under chromium (Cr) ion (III) stress. Methods The effects of 0–4 mM Cr(III) on the germination and seedling growth of alfalfa were first assessed. Subsequently, following seed NaHS immersion, the influence of H2S on alfalfa seed germination and seedling growth under 2 mM Cr(III) stress was investigated, and the substance contents and enzyme activities associated with ROS metabolism were quantified. Results Compared to the control group, alfalfa plant germination was delayed under 2 mM Cr(III) stress for up to 48 h (p < 0.05). At 120 h, the total seedling length was approximately halved, and the root length was roughly one-third of the control. Treatment with 0.02–0.1 mM NaHS alleviated the delay in germination and root growth inhibition caused by 2 mM Cr(III) stress, resulting in an increased ratio of root length to hypocotyl length from 0.57 to 1 above. Additionally, immersion in 0.05 mM NaHS reduced hydrogen peroxide (H2O2) and oxygen-free radicals (O2 · –) levels (p < 0.05), boosted glutathione (GSH) levels (p < 0.05), and notably enhanced catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) activities (p < 0.05) compared to the 2 mM Cr(III) stress treatment group. Conclusion Seed immersion in NaHS mitigated the delay in germination and inhibition of root elongation under 2 mM Cr(III) stress. This effect is likely attributed to the regulation of intracellular ROS homeostasis and redox balance through enzymatic and non-enzymatic systems; thus, providing a potential mechanism for combating oxidative stress.

Effect of localized fertilizer application on deep root development during early growth in upland rice under upland condition

ABSTRACT The effects of localized fertilizer (LF) application on changes in root system architecture (RSA) of upland rice seedlings under upland condition were evaluated, and root traits important for deep root development were identified using three root box experiments (Exps). Fertilizer was homogeneously mixed and broadcasted on the soil surface in two control treatments, while in three LF treatments, it was point-placed at 2.5, 7.5 and 12.5 cm below the soil surface. Nitrogen (N) fertilizer in Exp. 1, phosphorus (P) fertilizer in Exp. 2 and compound fertilizer with nitrogen, phosphorus and potassium (NPK) in Exp. 3 were used to compare the effects of LF. Localized N and NPK application altered the RSA through root proliferation and increasing root length percentage around the fertilizer-applied area, whereas localized P application had no effect on both root and shoot development. Deep root and shoot development were decreased with localized NPK application compared to homogeneously mixed control treatment but were maintained with localized N application, when applied at deeper soil depths. Furthermore, the increase in deep root length (DRL) was closely related to the increase in both total root length (TRL) and deep root length ratio (DRR). DRR increased with TRL in Exps. 2 and 3, while it was independent from TRL in Exp. 1, suggesting that DRL can be promoted by increasing DRR regardless of TRL. These results showed that localized N application at deeper soil depths could modify RSA of upland rice seedlings grown under upland condition without affecting shoot growth.

Impacts of reduced water availability on vegetative and reproductive traits of a Solanum species

AbstractWhile drought is known to affect crop yields negatively, there is limited knowledge of the strategies used by animal‐pollinated plants to cope with such conditions. In this study, we simulated low and moderate drought conditions in a greenhouse experiment and examined the vegetative and reproductive traits of a buzz‐pollinated species (Solanum lycopersicum). Our findings indicate that individuals exposed to both drought conditions decreased in height and bore fewer leaves but increased in the ratio of root length to dry mass. The number of flowers produced per day and the overall flower production were higher in plants under control conditions. We found no differences in the onset of flowering between the treatments, but the plants exposed to low drought showed peak flowering earlier. Among the morphometric traits, flower height, floral diameter, petal length, and petal width were significantly lower in both drought conditions. Individuals in the moderate‐drought treatment displayed greater variation in reproductive traits than those in the low‐drought treatment. Overall, drought stress negatively impacted the aboveground vegetative growth and the reproductive efforts of plants.

Tree morphology dependent transpiration reduction function of Schefflera arboricola for landfill cover restoration

Abstract Changes in hydrological processes and water resources required to sustain vegetation for ecological restoration of landfill covers and post mining sites in arid environments pose challenges in the context of extended droughts. Knowledge of actual threshold and wilting suction values based on tree morphological feature or plant age is essential for understanding the variation of root water uptake with drought stress and numerically predict the pore water pressure profile in root zone. The objective of this study is to quantify the transpiration reduction function (TRF; in terms of stomatal conductance (SC) and xylem sap flow (SF)) of Schefflera arboricola, considering the effects of tree morphology. Continuous drought condition was applied on the plant quantified with leaf area index (LAI) values at 0.5, 2 and 3.5, wherein each LAI represent tree age. The soil matric suction (ψ) and volumetric water content were measured by embedded sensors in the root zone. Based on the TRF obtained from SC values, a unique threshold suction (ψ NTR t) ranging from 30 to 50 kPa was identified. Beyond this ψ NTR t, measured leaf abscisic acid concentration increased up to 35 ng/mL, indicating the start of water stress avoidance mechanism. It is evident that ψ NTR t is independent of tree morphological parameter- leaf area to root length ratio (LA/RL). On the contrary, a threshold suction (ψ SAP t), depending on LA/RL ratio, can be determined, indicating the start of xylem cavitation. This ψ SAP t values ranging from 80 to 500 kPa depending on the LA/RL value, imply that the plant could significantly resist xylem embolization at higher LA/RL. In contrast, the plant with low LA/RL values have less tolerance of drought stress and hence low survivability. The results from this research study can be vital for devising and predicting plant available water in water scarce arid environments by a flux-based approach which is dependent on the tree age.

Effects of exogenous GABA on physiological characteristics of licorice seedlings under saline-alkali stress

Licorice is widespread in arid and semi-arid areas, but high soil salinity has always been a limiting factor for vegetation growth in these areas. Gamma-aminobutyric acid (GABA) is a signaling molecule that can regulate tolerance in plant. However, the mechanism by which exogenous GABA regulates the response of licorice to saline-alkali stress is not yet clear. In this study, we investigated the effects of exogenous GABA on growth parameters, oxidative damage, hormone levels and photosynthetic indices of licorice seedlings under different combinations of saline and alkali stress conditions. The experiment involved eight treatments: CK, distilled water (control); CK + GABA, 0.1 mM GABA; salt stress (SS), 150 mM NaCl; SS + GABA, 150 mM NaCl + 0.1 mM GABA; alkali stress (AS), 10 mM Na2CO3; AS + GABA, 10 mM Na2CO3 + 0.1 mM GABA; mixed saline-alkali stress (MAS), 150 mM NaCl + 10 mM Na2CO3; MAS + GABA, 150 mM NaCl + 10 mM Na2CO3 + 0.1 mM GABA. Our results showed that the inhibitory effects of SS and MAS on the seedling height, root length and root-shoot ratio were significantly alleviated by exogenous GABA. Although soluble sugars, chlorophyll a, total chlorophyll, and superoxide dismutase (SOD) activity were lower in the leaves of the seedlings in the SS treatment compared with the control, these physiological parameters increased significantly after GABA application. Exogenous GABA improved glutathione (GSH) activity in both the leaves and roots of the seedlings during the AS treatment. Additionally, take advantage of GABA led to an increase in ABA, GA and IAA contents in leaves under SS, AS and MAS treatments. Furthermore, the photosynthetic parameters, including Pn, gs, Tr, ETR and qP, significantly increased following the utilization of GABA in both the SS and MAS treatments. Therefore, the application of exogenous GABA can reduce the accumulation of harmful substances, preserve cell morphology, and enhance cell function under saline, alkali, and saline-alkali stress. This enhances the resistance of licorice seedlings to stress conditions and reduces physiological damage.

UNVEILING GENETIC THREADS: PHENOTYPIC EXPLORATION OF CHICKPEA (CICER ARIETINUM L.) GERMPLASMS FOR HERITABILITY AND TRAIT ASSOCIATIONS

The second most important self-pollinating legume crop in the world is the chickpea. Chickpea is an inexpensive source of protein that grows well in various climates. The current study aimed to evaluate the genetic advance and heritability of different characters at the seedling stage by analyzing their phenotypic attributes. During the 2022–2023 growing season, a randomized complete block design experiment was set up in the University of the Punjab's field area. The experiment included five different germplasms. At the seedling stage, data from seven morphological parameters were collected. ANOVA and correlation were performed using Statistix software. Seedling length, root length, and root-shoot ratio have shown low genotypic coefficients of variation (GCV) and phenotypic coefficients of variation (PCV), indicating a high environmental effect on these traits. Root length and leaf width had shown a strong correlation with seedling length. Path coefficient analysis directly affected root length and leaf width towards seedling length. Low genetic advance and high heritability were observed in root length, seedling length and root-shoot ratio, meaning selection should be delayed for one or more generations for such traits. Leaf width and leaf area have shown high heritability and genetic advance, suggesting that selecting such characters may lead to superior variety development based on phenotype.

Estimation of Crown Length, Root Length and Golden Divine Ratio in Extracted Permanent Maxillary and Mandibular Central Incisors: An In-vitro Study

Introduction: Human teeth serve many crucial functions, and aesthetics is one of these. Aesthetics and beauty are often correlated with the Golden Divine Ratio (GDR), a unique proportion hypothesised to exist in individuals or things with a harmonious appearance. Aim: To estimate the crown length, root length, and GDR in extracted human permanent maxillary and mandibular Central Incisors (CI) in the population of Tamil ethnicity from South India. Materials and Methods: This in-vitro cross-sectional study was conducted in the Department of Oral Pathology and Microbiology at Saveetha Dental College and Hospitals, Chennai, Tamil Nadu, India, from January 2023 to October 2023. The study included a total of 90 extracted human teeth from the Institutional tooth repository, out of which 27 were upper permanent CIs and the remaining 63 were mandibular CIs. Crown length and root length were measured using digital vernier calipers, and golden ratios were derived. Statistical Package for Social Sciences (SPSS) software version 26.0. was used for descriptive analysis and deriving means and standard deviation. Results: The average crown length, root length, and total length of upper CIs were 8.06±0.09 mm, 13.01±1.47 mm, and 21.06±2.36 mm, respectively. For the remaining 63 extracted permanent mandibular CIs, the mean crown length, root length, and total length were 7.85±0.66 mm, 12.6±0.97 mm, and 20.45±1.49 mm, respectively. The Root-to-Crown (R/C) ratio and Total Length to Root Length (T/R) ratio approximated 1.618 for both sets of teeth. Conclusion: The crown length of maxillary and mandibular CIs from the Tamil population followed the golden ratio in the present study.

Quantitative analysis of the root posture of Arabidopsis thaliana mutants with wavy roots.

Plant postures are affected by environmental stimuli. When the gravitational direction changes, the Arabidopsis thaliana mutants myosin xif xik (xif xik) and atp-binding cassette b19 (abcb19) exhibit aberrantly enhanced organ bending. Whether their phenotypes are due to the same mechanism is unknown. We characterized the primary root postures of these mutants. Their roots exhibited enhanced gravitropic bending with the same root-tip angles. The wavy roots of vertically grown plants were quantitatively evaluated using four indices. The straightness index (root base-to-tip length to total root-length ratio) was similar for xif xik and abcb19, and it slightly decreased for xif xik abcb19. The curvature index was similar for abcb19 and xif xik abcb19, but it decreased for xif xik, suggesting the ABCB19 deficiency caused the roots to curve more sharply. Combination of these indices for quantitative analyses of root postures may distinguish between similar wavy-root phenotypes and clarify genetic relationships.

Growth Performance of Soybean (Glycine max L. Merrill) treated with biochar under cadmium Stress

Cadmium (Cd) is a non-essential heavy metal that adversely affects plant growth. Biochar is predicted to facilitate plant growth. Under cadmium stress condition the effects of biochar on Soybean seedling growth, biomass production and SPAD value were poorly understood. In the current pot study Soybean was grown under different biochar and Cd combinations: 0% biochar and no Cd (control), 1.5% biochar, Cd (100 mg kg-1 of soil), Cd (100 mg kg-1 of soil) + 1.5% biochar. The results exhibited that under Cd stress shoot fresh weight (SFW), root fresh weight (RFW), shoot dry weight (SDW), root dry weight (RDW), shoot length (SL), root length (RL), whole plant biomass, stress tolerance index (%) and SPAD value decreased in Soybean, while root and shoot length ratio increased in comparison to control. Application of biochar solely or in addition of Cd enhanced SFW (14.07% with solely and 126.44% with Cd); RFW, SDW, RDW, SL and RL (156.66%, 55.89%, 61.29%, 21.14% and 16.62% with Cd, respectively), whole plant biomass (8.41% with sole biochar and 137.77% with Cd) and SPAD value (34.94% with Cd) in Cd-stressed Soybean. The sole application of biochar or Cd increased stress tolerance index (%) (SFSTI, RFSTI, SDSTI, RDSTI, SLSTI and RLSTIas recorded 114.04%, 92.25%, 104.47%, 105.78%, 100.73% and 99.22%, respectively; SFSTI, RFSTI, SDSTI, RDSTI, SLSTI and RLSTIvalue by 125.90%, 156.67%, 55.79%, 61.31%, 30.16% and 16.62% with Cd, respectively) in Cd-stressed Soybean. These results demonstrate that soil amendment with 1.5% biocharenhanced growth, biomass production and SPAD value of Soybean under Cd stress. It is therefore recommended that biochar can be used as effective tool to mitigate the detrimental effect of Cd stress on Soybean seedlings. South Asian J. Agric., Vol. 9, No.1&amp;2, 2022-‘23: 22-30

Relationship between the trait response of aboveground and belowground parts of dominant plant species to groundwater depth change in Horqin Sandy Land, eastern China

Climate change and human development will lead to an increase in groundwater levels. This will have a particularly severe impact on arid ecosystems that are highly dependent on groundwater, as overconsumption and pollution of water resources can lead to faster depletion of groundwater. This not only exacerbates the problem of groundwater scarcity, but also may have profound impacts on local ecological environment and biodiversity. However, previous research has focused on aboveground trait responses to precipitation deficits, with less emphasis on concomitant belowground impacts and deep soil drought from groundwater depletion. Therefore, it remains unclear how groundwater depletion affects above and belowground traits of plant to jointly regulate aboveground biomass. In this study, we assessed morphological and ecophysiological traits of two dominant species (herb: Pennisetum centrasiaticum and shrub: Artemisia halodendron) across three groundwater depth (50 cm, 100 cm, and 200 cm) in the Horqin Sandy Land in China, within which photosynthetic rate (Photo), stomatal conductance (Cond), transpiration rate (Tr), internal CO2 concentration (Ci), instantaneous water-use efficiency of leaves (Lwue), total nitrogen (LN) and phosphorus (LP) content of the leaves, root to shoot ratio (RSR), root length density (RLD), total root length (RTL), root length ratio (RLR) were measured. The result showed that the two species growing with increased groundwater depth had reduced photosynthetic rate, and regulated stomatal close to aggregate ability of instantaneous water use efficiency, which may allow plants to meet resource demands under drought stress avoiding transpiration water loss. Plants also reduced the density of all roots and adjusted the vertical distribution of coarse root by changing biomass distribution to acquire deeper soil available water. Correlation analysis showed that the vital traits for aboveground biomass responses appear to be groundwater depth, soil moisture, leaf area, photosynthesis, water use efficiency, and root traits. Overall, the biomass production response of two dominant species may be greatly influenced by the interaction between aboveground and belowground traits in response to changes in groundwater depth. This result contributes to our understanding of adaptive strategies of vegetation in sandy soils and provides additional support for enhancing vegetation productivity in semi-arid ecosystems. The ability of semi-arid ecosystems to predict vegetation dynamics under current and future increasing groundwater depths is crucial.

Phosphorus enrichment enabled Amorpha fruticosa to invade on the floodplain of the Tagliamento River, Italy

The North American nitrogen-fixing shrub Amorpha fruticosa (false indigo) is an aggressive invader of riverine habitats in Europe, though the reasons for its success are poorly understood. We hypothesized that its spread on the floodplain of the Tagliamento River in Northern Italy was enabled by anthropogenic phosphorus (P) enrichment. To investigate this hypothesis, we surveyed seed production at different locations along the river and performed a growth chamber experiment in which seedlings of three common floodplain shrubs (A. fruticosa, Salix eleagnos and Buddleja davidii) were grown at 10 levels of both nitrogen (N) and P. As a bioassay of N and P availabilities, we analyzed concentrations of these nutrients in Salix eleagnos leaves collected at different positions along the river. P availability was significantly higher in the lower reaches of the river, where A. fruticosa was abundant, than at its upstream limit. Numbers of A. fruticosa seeds per inflorescence increased strongly in a downstream direction and there was a trend for higher seed weight. In the growth experiment, A. fruticosa was more P-demanding than the other species, producing little biomass and no rhizobial nodules at low P. It also exhibited greater plasticity than the other species in both root mass fraction and ratio of longest root length to root mass. We conclude that anthropogenic P enrichment enabled A. fruticosa to invade what was originally a very oligotrophic environment. This N2-fixing shrub exhibits greater phenotypic plasticity than native S. eleagnos, giving it a competitive advantage under conditions of high P availability.

Impact of Pre-Sowing Physical Treatments on The Seed Germination Behaviour of Sorghum (Sorghum bicolor)

In the emerging global food scenario, sorghum is a healthy cereal crop used by human beings and has been recognized to have considerable potential to be used in a variety of food products. Germination is a natural processing technique used for the biological activation of grains to improve their nutritional and functional properties. In order to improve the germination of grains, different techniques have been established; therefore, the current study was conducted to analyze the effect of ultrasound and microwave techniques on sorghum grain germination parameters. Overnight steeped sorghum grains were divided into four groups. The first group was not subjected to any treatment. The second group was subjected to ultrasonic treatment, the third group was exposed to microwave treatment, and the fourth group was treated with combined MW &amp; US applications for different intervals. Germinated grains were measured for the shoot length and root length, total weight, germination %, seedling vigor index, and the ratio of root length versus shoot length. It was found that ultrasound-processed treatment US1 (40% amplitude for 5 min) and microwave-processed treatment MW2 (700 W for 5 sec) significantly improved the germination parameters. Pre-sowing physical techniques cause disturbance of the seed coat, which enabled water diffusion into the seeds inducing a higher rate of enzymatic reactions, and the start of the initial development stages consequently resulted in faster and more effective germination.

Changes in mass allocation play a more prominent role than morphology in resource acquisition of the rhizomatous Leymus chinensis under drought stress.

Plants can respond to drought by changing their relative investments in the biomass and morphology of each organ. The aims of this study were to quantify the relative contribution of changes in morphology vs. allocation and determine how they affect each other. These results should help us understand the mechanisms that plants use to respond to drought events. In a glasshouse experiment, we applied a drought treatment (well-watered vs. drought) at early and late stages of plant growth, leading to four treatment combinations (well-watered in both early and late periods, WW; drought in the early period and well-watered in the late period, DW; well-watered in the early period and drought in the late period, WD; drought in both early and late periods, DD). We used the variance partitioning method to compare the contribution of organ (leaf and root) biomass allocation and morphology to the leaf area ratio, root length ratio and root area ratio, for the rhizomatous grass Leymus chinensis (Trin.) Tzvelev. Compared with the continuously well-watered treatment, the leaf area ratio, root length ratio and root area ratio showed increasing trends under various drought treatments. The contribution of leaf mass allocation to leaf area ratio differed among the drought treatments and was 2.1- to 5.3-fold greater than leaf morphology, and the contribution of root mass allocation to root length ratio was ~2-fold greater than that of root morphology. In contrast, root morphology contributed more to the root area ratio than biomass allocation under drought in both the early and late periods. There was a negative correlation between the ratio of leaf mass fraction to root mass fraction and the ratio of specific leaf area to specific root length (or specific root area). This study suggested that organ biomass allocation drove a larger proportion of variation than morphological traits for the absorption of resources in this rhizomatous grass. These findings should help us understand the adaptive mechanisms of plants when they are confronted with drought stress.

Effect of Seed Source on Seed Vigour and Field Performance of the Sorghum [Sorghum bicolor. (L.) Moench] Cultivar Taba

A set of laboratory tests and field experiments were conductedfor two consecutive seasons (2009/10 and 2010/11) to investigate theeffect of seed source on seed quality attributes of the sorghum cultivarTabat. Simple correlation coefficients were calculated to determine thedegree of association between the different vigour tests and seedlingemergence under field conditions. Seeds were obtained from fourlocations: two rainfed (Damazin and Habeela) and two irrigated (KhashmEl Girba and El Gezira). Data were collected on initial seed moisturecontent, 1000-seed weight, germination percentage, rate of germination,seedling shoot length, seedling root length, seedling shoot to root lengthratio, seedling fresh weight, seedling dry weight, plant height, number ofleaves per plant, leaf area per plant and plant fresh and dry weight. Theresults indicated that, under laboratory conditions, seed source hadsignificant effect on seedling root length and fresh weight in the firstseason, on germination percentage and rate of germination in the secondseason and on seed moisture content and 1000 seed weight in bothseasons. Significant differences were found in seedling shoot length andplant height under field conditions. Seeds from Habeela and Damazinperformed well with regard to germination percentage, rate ofgermination and field seedling emergence. Also, seeds from the rainfedareas produced taller plants than those from irrigated areas (Khashm ElGirba and El Gezira). The results also showed that field seedlingemergence was positively correlated with the estimate, under laboratory

Negative relationship between topsoil root production and grain yield in oat and barley

Production and maintenance of vegetative organs is costly for cereal crops, and thus it should be advantageous for crop production to produce no more roots and shoots than necessary to ensure maximum output. Excessive growth of vegetative organs may be genetically determined or triggered by resource deficiency or competition. While aboveground structures have received much attention from breeders, the same is not true of roots, which are not so readily observable. The purpose of this study was to examine the relationship between collective crop yield and vegetative growth parameters under favourable abiotic conditions in densely sown monocultures of oat and barley, with specific focus on root traits in the topsoil. A diverse set of existing varieties, as well as original crosses within both species were sown as monoculture patches in the field. Significant negative relationships were found between several root length-related traits and grain or protein yield in both species. Among oat crosses, we found a significant negative relationship between topsoil root length density and both grain and protein yield. In barley, the negative relationship between root length and yield was tied to shoot biomass - plants that grew longer roots per unit shoot biomass (root length ratio) produced lower grain yields. The results indicate that plants produced longer roots in the topsoil than necessary for maximum yield. While we cannot state with certainty the cause of the observed negative relationships between root growth and yield parameters, the results still suggest that root growth redundancy exists in cereals.

Elucidation of genetic variability, heritability, correlation and path coefficient in carrot (Daucus carota L.)

An experiment was conducted at the Punjab Agricultural University, Ludhiana, India, for 2 years (2019-20 and 2020-21), to study the genetic variability, heritability, correlation and path coefficient analysis in 28 genotypes of Asiatic carrot under 8 environments. The experiment was laid out in RBD with three replications. The analysis of variance showed that the genotype’s mean sum of squares was significant for all the traits studied, indicating that significant variation existed among them. A wide range of variation existed for average root length, root weight, root diameter, core diameter and root shoot ratio i.e., 14.5-21.0 cm, 40.9-77.8 g, 2.2-2.7 cm, 0.93-1.56 cm and 0.86 to 1.29, respectively. The average marketable yield of genotypes ranged between 365.55 to 584.55 q ha-1. Vegetative traits like shoot length varied from 42.0-64.7 cm, shoot weight from 44.71-80.14 g, and the number of leaves from 5.4 -7.2 among all genotypes. The magnitude of phenotypic coefficient of variation was greater than the corresponding genotypic coefficient of variation for all the traits indicating that trait expression is environmentally influenced. Root-shoot ratio, shoot length, number of leaves, root length, and root diameter all have exhibited highest heritability and moderate genetic advance that suggested additive gene action. Strong character association of root length, root diameter and root weight with marketable yield suggested as selection criteria for higher yield.

Effects of irrigation on root growth and development of soybean: A 3-year sandy field experiment.

Increasing the water use efficiency of crops is an important agricultural goal closely related to the root system -the primary plant organ for water and nutrient acquisition. In an attempt to evaluate the response of root growth and development of soybean to water supply levels, 200 genotypes were grown in a sandy field for 3 years under irrigated and non-irrigated conditions, and 14 root traits together with shoot fresh weight and plant height were investigated. Three-way ANOVA revealed a significant effect of treatments and years on growth of plants, accounting for more than 80% of the total variability. The response of roots to irrigation was consistent over the years as most root traits were improved by irrigation. However, the actual values varied between years because the growth of plants was largely affected by the field microclimatic conditions (i.e., temperature, sunshine duration, and precipitation). Therefore, the best linear unbiased prediction values for each trait were calculated using the original data. Principal component analysis showed that most traits contributed to principal component (PC) 1, whereas average diameter, the ratio of thin and medium thickness root length to total root length contributed to PC2. Subsequently, we focused on selecting genotypes that exhibited significant improvements in root traits under irrigation than under non-irrigated conditions using the increment (I-index) and relative increment (RI-index) indices calculated for all traits. Finally, we screened for genotypes with high stability and root growth over the 3 years using the multi-trait selection index (MTSI).Six genotypes namely, GmJMC130, GmWMC178, GmJMC092, GmJMC068, GmWMC075, and GmJMC081 from the top 10% of genotypes scoring MTSI less than the selection threshold of 7.04 and 4.11 under irrigated and non-irrigated conditions, respectively, were selected. The selected genotypes have great potential for breeding cultivars with improved water usage abilities, meeting the goal of water-saving agriculture.