Taproot Diameter Research Articles

Effect of Different Growing Media and Polybag Sizes on Seeds Germination & Root System of Rough Lemon (Citrus jambhiri Lush.) in Nursery Condition

Aims: The study aimed to evaluate the different growing media & polybag size for seedling growth of rough lemon rootstock. Study Design: The experiment used a Complete Randomized Design (CRD) with three replications. Place and Duration of Study: The study "Effect of Growing Media and Polybag Size on Rough Lemon Seedling Growth" took place in an insect-proof net house at CCS Haryana Agricultural University during the 2021-2022 academic year. Methodology: It comprising of 30 treatment combination i.e., ten different growing media: T1: garden soil; T2: soil: sand (1:1); T3: soil: sand: leafmold (1:1:1); T4: soil: cocopeat (1:1); T5: sand: cocopeat (1:1); T6: soil: sand: cocopeat (1:1:1); T7: soil: FYM (1:1); T8: sand: FYM (1:1); T9: soil: sand: FYM (1:1:1); T10: soil: sand: FYM: cocopeat (1:1:1:1), and the polybags S1: large (30 x 18 cm), S2: medium (21 x 18 cm) & S3: small size (17 x 16 cm) bags. Results: The study found that adding cocopeat to growing media (T4, T5, T6) resulted in earlier germination and higher rates (87-89%) Whereas, T4 to T10 media consists of either FYM, cocopeat for both resulted into more germination 87-89% as compared to controls (T1, T2, T3). The most of the root growth parameters i.e., diameter of tap root(2.45mm), fresh root weight (4.63g) & dry root weight (1.21g) & root: shoot ratio (0.61) improved with the media sand: FYM, soil: FYM, sand: soil: FYM, sand: soil: FYM: cocopeat in equal proportion. However, when media supplemented with cocopeat (T4, T5 & T6 ) also showed appreciable results as compared to soil, sand: soil & soil: sand: leafmold. However, sand: FYM, sand: cocopeat treatments were best in respect of number of primary roots (61.22), root volume (6.44ml). Whereas, sand: soil showed very poor results in all growth aspects. Among polybags sizes, large size (30 x 18cm) bags performed best in most of the germination & root growth parameters. Conclusion: Media enriched with organic matter outperformed sole media across all parameters, while larger polybags produced significantly better results than medium and small sizes.

Response of Auxin, Carbohydrate and Lignin Metabolism to Habitat during the Development of Ginseng Taproot

Panax ginseng taproot serves as a crucial storage organ and constitutes a significant component of Chinese herbal medicine. In China, ginseng is cultivated using two primary methods: under-forest planting and farmland planting. These methods create distinct habitats that notably influence the morphology of ginseng taproots. However, the precise regulatory mechanisms governing ginseng taproot expansion remain to be fully elucidated. This study aimed to delineate the patterns of ginseng taproot expansion by examining taproots transplanted into farmland (TCG) and forest environments (TLCG and TQCG). Our findings indicate that light intensity and soil available potassium levels in TCG plots significantly exceed those in TLCG and TQCG plots. Compared with TLCG and TQCG, the taproot diameter of TCG increased by 11.54% and 27.73%, respectively. At the same time, combined with the microstructure of the transverse section of the taproot, it showed that the expansion of the TCG taproot was closely related to cell expansion. During TCG taproot expansion, there was an increase in indole-3-acetic acid (IAA) content, significant starch accumulation, and a decrease in lignin content. By analyzing the expression of key genes, we found that compared with TLCG and TQCG, the expression of genes PgTPS1 and PgALDH1 was upregulated, and the expression of genes PgHCT1, PgPAL3, PgPER3, and PgPER51 were downregulated in TCG taproot. Additionally, the transcription factors PgARF18.1 and PgbHLH42 were identified as responsive to habitat changes, playing pivotal roles in taproot expansion. In conclusion, this study provides foundational insights into the regulatory mechanisms of ginseng taproot expansion, offering significant implications for enhancing the quality and value of ginseng.

Root traits and biomass production of drought‐resistant and drought‐sensitive arabica coffee varieties growing under contrasting watering regimes

AbstractDrought is a major factor affecting coffee production, and different genotypes exhibit varying degrees of resistance to drought stress. We examined root traits and biomasses of drought‐resistant (74110, Angafa, Bultum, Chala, and Gawe) and drought‐sensitive (75227, Koti, Melko CH2, Menasibu, and Mokah) Coffea arabica varieties at seedling stage under contrasting watering regimes (water stressed and well watered) for 30 days followed by 15 days of recovery to identify the association between drought resistance and root traits and dry matter partitioning, and the impact of drought stress on growth performance of arabica coffee varieties. We used a split‐plot design with three blocks, where watering regime was the whole‐plot factor and variety was the subplot factor. During water‐stress and recovery periods, the interaction effect between watering regime and variety significantly affected root traits and dry matter partitioning, while the watering‐regime main effect affected biomass. We observed a higher (1) tap root diameter (0.34 cm), lateral root number (80.7), and root volume (4.7 cm−3) for 74110; (2) lateral root number (79.3), specific root length (24.8 cm g−1), and root‐mass ratio (0.41 g g−1) for Bultum; and (3) root length density (3.3–5.2 cm cm−3), root angle (42.6°–47.8°), root‐mass ratio (0.40–0.42 g g−1), and root‐shoot ratio (0.67–0.72 g g−1) for Angafa, Chala, and Gawe under water‐stressed condition. During both study periods, biomasses were much lower under water‐stressed than under well‐watered condition. The findings show the association between drought resistance and root traits and dry matter partitioning, and the impact of drought stress on growth performance of young arabica coffee.

Elucidating the genomic regions through genome-wide association study (GWAS) for root traits in cowpea (Vigna unguiculata (L) Walp) mini-core collection

Enhancing the root traits through selection and breeding efforts can significantly improve the acquisition of soil resources, consequently boosting crop production in marginal environments. Cowpea is one of the important legume crops in arid and semi-arid regions, grown mostly in marginal environments under drought conditions. The roots play a crucial role in plant's ability to survive and adapt under such water stressed conditions. The understanding of cowpea genetic architecture related to root system architecture (RSA) remains limited due to difficulties in accurately measuring root traits. In the present study, a set 110 diverse mini-core collection of cowpea from IITA, Nigeria was evaluated for thirteen (13) different root-shoot traits under controlled conditions in the green house. Significant variation was recorded for all the root traits in the mini-core set. Most promising genotype for most of the root traits, viz., root volume, dry root weight, root biomass density and tap root diameter were identified. The correlation analysis revealed significant positive association (p < 0.001) of root weight with shoot weight (0.85), root volume (r = 0.61), and tap root diameter (0.56). In the principal component analysis (PCA), first three principal components explained the variance of 64.31%, with PC1 contributing 44.43%, PC2 10% and PC3 9.88%. All the root-shoot traits contribute positive variation to PC1especially dry root weight and dry shoot weight that had high component loading and in PC2 root shoot ratio had high loading. The root-shoot trait data was used with 6,574 good quality SNP data for discovery of genes/QTLs/marker-trait associations for root traits. The analysis of results of genome wide association study (GWAS) led to the identification of 52 unique SNPs associated significantly (p < 10−4) with thirteen root-shoot traits. Highest number of SNPs was found associated with root weight and chromosome 5 was identified as SNP hotspot for harboring majority of significant SNPs. We further delve candidate genes within 50 kb around the identified SNP that led to the identification of several important candidate genes underlying genomic regions responsible for root-shoot traits in cowpea. The promising cowpea genotypes for root traits and promising MTAs/candidate genes will prove useful in cowpea improvement programs including improvement of drought tolerance in cowpea.

The effect of exogenous melatonin on root growth and lifespan and seed cotton yield under drought stress

Drought stress is the major environmental factor that inhibits the growth and reduces the yield of cotton (Gossypium hirsutum L.). The exogenous application of melatonin has been shown to alleviate drought stress damage, but it is unclear whether melatonin mediates the alleviation by preventing the drought-induced inhibition of root growth. To address this gap, we subjected cotton plants grown in RhizoPotsto treatments of thorough watering, drought stress treatment, and drought stress supplemented with exogenous melatonin. Melatonin promoted the aboveground growth compared with the non-melatonin treatment under drought stress, and increased the plant height, stem diameter, leaf area, SPAD value, and net photosynthetic rate. The application of melatonin significantly prevented the drought-induced yield losses by increasing the boll weight. The drought stress+melatonin treatment significantly increased the root length, root surface area, root volume, and specific root length by 18.36%, 25.46%, 26.07%, and 18.53%, respectively, compared with the drought stress treatment. Under drought stress, melatonin increased the root length by increasing its maximum and average rates of accumulation and increased the taproot diameter by increasing its maximum and average rates of accumulation. The drought stress+melatonin treatment significantly increased the lifespan of lateral roots and root hairs compared with the drought stress treatment. In conclusion, this study indicated that exogenous melatonin could improve the drought resistance and yield of cotton by promoting root growth and delaying root senescence.

Improvement of Papaya (Carica papaya L.) Seed Germination, Seedling Growth and Chlorophyll Content by Using Growing Medium and Organic Liquid

A pot experiment was conducted during rainy season (July month) of 2019 at nursery unit of Horticulture Department, College of Agriculture, Ummedganj, Kota to evaluate the impact of growing media and cow urine on seed germination, seedling growth and chlorophyll content of papaya (Carica papaya L.) cv. Arka Surya. The experiments were laid out in a factorial complete randomized design with two factors consisting 11 growing media and 2 level of cow urine (with or without). Among different treatments combination used the medium Soil + Sand + Vermiculite + Cocopeat + Perlite (1:1:1:1:1) with cow urine found significantly superior over other treatments and control with respect to lowest days required for first germination (6.17 days) and higher germination percentage (90.24 %). It has given better seedling height (15.48 cm), number of leaves per seedling (9.83) and leaf area (51.85 cm2) at 75 days after sowing. The maximum length of longest tap root (14.20 cm), diameter of tap root (4.12 mm) and root/shoot ratio (0.87) were also found significantly superior in the same treatment as compared to rest of the treatments. Further, it was also found superior with relation to highest chlorophyll (2.50 mg/100g). Therefore, it is recommended this growing medium combination along with cow urine should be used for better germination and growth of papaya seed by orchardist.

Effects of Transplantation and Microhabitat on Rhizosphere Microbial Communities during the Growth of American Ginseng

Transplanting has been widely used in American ginseng (Panax quinquefolium L.) cultivation in Northwest China to mitigate the negative effects of continuous cropping obstacles. Because of the accumulation of pathogenic microorganisms and the change in soil properties, transplanting American ginseng to newly cultivated fields after two years of growth has become a major planting pattern. Despite transplanting improving the quality of American ginseng, the effects of soil properties and microbiota on growth during the transplanting process are poorly understood. In the present study, microbial communities, soil physico-chemical properties and morpho-physiological parameters were analyzed to investigate the effects of microbiota and soil characteristics on American ginseng growth in both soil and ginseng root microhabitats. Results indicated that the structure and species of bacterial and fungal communities changed significantly in different microhabitats before and after transplantation. Moreover, the assemblage process of the bacterial community was dominated by deterministic processes. The stochastic process ratio increased and niche breadth decreased significantly after transplanting. While the assembly of the fungal community was dominated by stochastic process, and there was no significant difference in NST, βNTI or niche breadth before and after transplanting. Bacterial co-occurrence networks demonstrated a higher connectivity but a lower aggregation in soil microhabitat, while the fungal community networks remained stable before and after transplantation. Gammaproteobacteria was the biomarker in the soil microhabitat, while Alphaproteobacteria, Betaproteobacteria and Gemmatimonadetes were biomarkers in the ginseng root microhabitat. Sordariomycetes was a biomarker with high relative abundance in the fungal community before and after transplanting. The bacterial functional and important ASVs were significantly correlated with pH, organic matter, total nitrogen, available phosphorus, total potassium root fresh weight, taproot diameter and stem height of American ginseng. Partial least squares path modeling showed that soil properties significantly affected the formation of different microbial specific ASVs. The important functional ASVs in ginseng root microhabitat had a positive effect on American ginseng growth, while the rare taxa had a negative effect. Our results provide a good starting point for future studies of microbial community succession in different microhabitats influenced by the transplantation pattern of American ginseng.

Responses of differentially expressed proteins and endogenous hormones in winter rapeseed (Brassica rapa L.) roots under water deficit stress

AbstractWinter rapeseed (Brassica rapa L.) can well‐adapt to environmental conditions such as barrenness, water deficit and low temperature in arid and semi‐arid planting regions and is the preferred rapeseed type. In this study, we analysed changes of root system morphology, antioxidant enzyme activity, endogenous hormone contents and differentially expressed proteins (DEPs) under control (CK), slight water deficit (SWD, 50–55% of maximum field water capacity), moderate water deficit (MWD, 40–45% of maximum field water capacity) and high water deficit (HWD, 30–35% of maximum field water capacity) conditions. Winter rapeseed experienced taproot elongation, decreased taproot diameter and increased lateral root number, under water deficit stress. The accumulation of reactive oxygen species (ROS) can cause membrane system peroxidation, and antioxidant enzyme activity increases to remove ROS. Changes in jasmonic acid (JA), salicylic acid (SA), cytokinin (CTK), auxin (IAA) and gibberellin (GA) levels promote the absorption of water and minerals by driving changes in the root system architecture to resist water deficit stress. A proteomic analysis has shown that DEPs are involved in energy metabolism, antioxidation response, osmotic regulation, hormone signal transduction, protein metabolism and the stress response, and these proteins are located in the peroxisome, chloroplast, mitochondrion, cell wall, vacuole, cytoplasm, extracellular space and cell membrane. In this study, multiple DEPs (malate dehydrogenase cytoplasmic 1 OS, 14‐3‐3‐like protein GF14 Psi, GA 3‐beta‐dioxygenase, glutathione reductase and jasmonate‐inducible protein) were involved in the root system architecture, revealing the complexity of the root response to water deficit. Significant/extremely significant synergistic relationships were observed between antioxidant enzyme activity and endogenous hormone contents. In conclusion, ROS, endogenous hormones and stress‐related proteins work synergistically to control the root system architecture of winter rapeseed roots in response to water deficit stress.

Analysis of Soil and Crop Parameters for the Development of Power Tiller-Operated Groundnut Digger

Groundnut (Arachis hypogea L.) is a major oilseed crop and holds an important place in the Indian agricultural economy. Odisha occupies 6th place in the major groundnut-producing states of the country with a total production of 0.388 MT and is grown in both Kharif and Rabi seasons. Harvesting is one of the major unit operations in groundnut cultivation and is mechanically harvested by tractor-operated diggers but their use is limited because of small land holdings and high capital costs and is not economical for small and marginal farmers of the state. However, the groundnut diggers to match with power tillers are not commercially available, therefore, efforts were made to develop a single-row groundnut digger operated by a power tiller. The study was conducted to relate the soil and crop parameters for the digger design, which influences the harvesting of groundnut. The design of a power tiller-operated groundnut digger to harvest a single row of groundnut requires the data of soil parameters (soil type, bulk density, cone index and soil moisture content) and crop parameters (plant population, plant height, pod zone, pod spreading radius, taproot length, taproot diameter, pod-vine ratio), suitable for different groundnut varieties. It was found that the majority of groundnut varieties were grown in sandy soils and harvested at 12-15 % soil moisture for more yield with a minimum power requirement. It was observed that for all types of groundnut varieties the plant population, plant height, pod zone depth, pod spreading radius, taproot length, taproot diameter and the number of pods per plant varies from 24-29/m2, 31-49.18 cm, 5.79-6.86 cm, 5.87-9.15 cm, 11.70-13.78 cm, 4.64-5.84 cm and 11-27/plant, respectively.

Root morphology, growth, and physiology in Begonia (Malus × micromalus) grown in copper hydroxide containers

A major concern with container seedlings is root circling and deformation that will affect post-planting performance and stability. To improve root quality, 3-year-old Begonia ( Malus × micromalus) plants were grown in the containers treated on interior surfaces with different concentrations of copper hydroxide (Cu(OH)2) (0, 40, 80, 120, 160, and 200 g L−1) for 1 year. Compared with the standard container control (SC) and carrier asphalt container control (AC), the number of terminal lateral roots and lateral root volume were increased by 21% and 13% at 80 and 120 g L−1 Cu(OH)2 but decreased by 8% and 10% at 200 g L−1 Cu(OH)2. Only 80 g L−1 Cu(OH)2 increased the plant height and root weight, while other concentrations of Cu(OH)2 resulted in the declines. Phosphorus and potassium were improved with lower concentrations of Cu(OH)2 but decreased with 160 and 200 g L−1 Cu(OH)2. No significant difference in the concentrations of soluble protein and sugars in leaves was observed between Cu(OH)2 treatments and the controls. AC decreased nitrogen concentration in leaves by 12% over the SC across the whole growing season and increased taproot diameter by 17%. Our results indicate that 80 g L−1 Cu(OH)2 was the optimum concentration for root pruning and the maintenance of physiological function. Disadvantages in growth and physiology gradually showed up with increased concentrations.

Effect of dolomite and pig manure on growth and production of carrots (Daucus carota)

Abstract. Sambi ND, Limbongan Y, Pata’dungan AM. 2023. Effect of dolomite and pig manure on growth and production of carrots (Daucus carota). Nusantara Bioscience 14: 22-29. This study aims to see how dolomite and pig manure affect carrot (Daucus carota L.) plant development and taproot production. The research was conducted from May to August 2021 in the Padangiring Village, Rantetayo Sub-district, Tana Toraja District, South Sulawesi, Indonesia. Three levels of dolomite in combination with four levels of pig manure were used: control (no treatment), and dolomite at 3 tons/ha, 6 tons/ha, and pig manure at control (no treatment), and 20 tons/ha, 30 tons/ha, and 40 tons/ha. The optimal dolomite level of 3 tons/ha significantly influenced plant height, the number of leaves, taproot length, and taproot diameter but had no significant effect on individual taproot weight, plot taproot weight, or taproot weight per hectare. The optimal pig manure dose of 4 kg/plot (40 tons/ha) showed a substantial influence on all investigated variables. The interaction between dolomite and pig manure substantially influenced taproot length but had no effect on the other observable variables. The optimum treatment combination was 3 tons/ha of dolomite with 40 tons/ha of pig manure, yielding 38.67 tons/ha of carrot taproots. Thus, commercial carrot growth and production may be boosted by a combination of dolomite and pig manure.

Effect of Arbuscular Mycorrhizal Fungi and Bio - Inoculants on Germination and Seedling Growth of Carica papaya L. Var. Gujarat Junagadh Papaya-1

Background: Glomus intraradices fungi and three bio-inoculants (Pseudomonas fluorescens, Trichoderma viride, and Trichoderma harzianum) are known to have certain beneficial effects on germination and seedling growth of several tropical fruit crops. A pot study was conducted to evaluate the effects of arbuscular mycorrhizal (AM) fungi and bio inoculants on seed germination and seedling growth of a papaya cultivar Gujarat Junagadh Papaya-1 at regional horticultural research station (RHRS), ASPEE College of Horticulture and Forestry (ACHF), Navsari Agricultural University, Navsari, Gujarat, India.&#x0D; Methods: The seeds of papaya were sown in the Monsoon season (June-Aug 2019) in polybags. The seeds of papaya were coated by AM fungi (G. intraradices), three bio inoculants, and their combinations. There were 9 treatments including control treatment.&#x0D; Results: An application of T. harzianum was found to be the most effective on seed germination and seedling growth by enhancing germination percentage (89%) along with early emergence (6 days) and consolidating all the growth parameters. T. harzanium was also effective on underground plant parts such as tap root length and diameter. The combination of all four bio-inoculants also gave significant results. Results from this study could be helpful for the West Indian fruit growers by enhancing the opportunities to use bioagents for sustaining their farming systems.

Root System Architecture and Symbiotic Parameters of Summer Mung Bean (Vigna Radiata) under Different Conservation Agriculture Practices

Root system architecture plays a vital role in plant growth, development, and adaptation by absorbing water and nutrients and providing mechanical support for growing plants. Unfortunately, little information is available in the literature on the root dynamics of summer mung bean under conservation agriculture conditions. In this study, field experiments were conducted during the summer seasons of two consecutive years (2020 and 2021) to investigate the root system dynamics of summer mung bean under different conservation agriculture practices. The highest stem and system width, depth to width length, number of nodal roots, taproot diameter, secondary root length (both right and left) of summer mung bean were recorded in the Soybean (permanent bed; PB)-Wheat(PB)-Summer mung (PB)(+Residual; +R) based cropping systems, followed by Maize(PB)-Wheat(PB)-Summer mung (PB)(+R), while, the lowest values of above parameters were recorded in the Puddled Transplanted Rice–Conventional till (PTR-CT)Wheat-Summer mung (-R). Further, the pod length, number of seeds per pod, number of pods per plant, seed yield and symbiotic parameters (including number of nodules per plant, leghaemoglobin content) and root dry weight were recorded highest in Soybean (PB)-Wheat (PB)-Summer mung (PB)(+R). Interestingly, the yield of summer mung bean increased around 13.4–29.5% when residues were retained on the soil surface with treatments involving residual removal. The soil dehydrogenase enzyme activity increased significantly under Soybean (PB)-Wheat (PB)-Summer mung (PB)(+R) based cropping system as compared to PTR-CT Wheat-Summer mung (-R). In addition, the number of pods per plant exhibited a significantly positive correlation with yield during both crop seasons. Overall, this study suggests that the inclusion of summer mung in soybean-based cropping systems may substantially improve the root architecture and soil quality and increase crop yield under conservation agriculture.

Effect of Root Pruning on the Root Growth Potential (RGP) of Three Philippine Native Tree Species

Root growth potential (RGP) is the plant’s capacity to grow new roots, an important trait for seedlings to be used on any reforestation program. In the Philippines, these kinds of programs often end up in failure, as low-quality seedlings are usually chosen due to unfamiliarity with attributes that indicate good outplanting performance, narrow sources of high-quality seeds, and the lack of a reliable quality assessment method. This study aimed to determine the RGP of three native species – namely, bignai (Antidesma bunius), kamagong (Diospyros blancoi), and molave (Vitex parviflora) – and find its correlation with other morphological parameters. The experiment was done in a completely randomized design (CRD) with taproot pruning lengths (1-cm pruning, 2-cm pruning, and no root pruning) applied as treatments for each species. The morphological parameters measured included the relative growth rate (height and diameter), number of leaves, root collar diameter (RCD), biomass (root, shoot, and total) and length of taproot while root-shoot ratio, sturdiness quotient, and seedling quality index (SQI) were calculated. In general, taproot pruning had no significant effects on the seedling morphological attributes of all species. Excluding molave, the two other species had mostly responded well to root pruning and can be recommended as a treatment to induce root growth development. RGP had generally complemented the results from the other parameters, indicating how root development was associated with the morphological growth of the species. The study shows how RGP can also be relied on for testing seedling health and the status of native species. For a more comprehensive result, future research could increase experiment duration or use younger seedlings. A field performance assessment could also be performed to supplement the RGP study

Associated SNPs, Heritabilities, Trait Correlations, and Genomic Breeding Values for Resistance in Snap Beans (Phaseolus vulgaris L.) to Root Rot Caused by Fusarium solani (Mart.) f. sp. phaseoli (Burkholder)

Root rot is a major constraint to snap bean (Phaseolus vulgaris) production in the United States and around the world. Genetic resistance is needed to effectively control root rot disease because cultural control methods are ineffective, and the pathogen will be present at the end of one season of production on previously clean land. A diversity panel of 149 snap bean pure lines was evaluated for resistance to Fusarium root rot in Oregon. Morphological traits potentially associated with root rot resistance, such as aboveground biomass, adventitious roots, taproot diameter, basal root diameter, deepest root angle, shallowest root angle, root angle average, root angle difference, and root angle geometric mean were evaluated and correlated to disease severity. A genome wide association study (GWAS) using the Fixed and random model Circulating Probability Unification (FarmCPU) statistical method, identified five associated single nucleotide polymorphisms (SNPs) for disease severity and two SNPs for biomass. The SNPs were found on Pv03, Pv07, Pv08, Pv10, and Pv11. One candidate gene for disease reaction near a SNP on Pv03 codes for a peroxidase, and two candidates associated with biomass SNPs were a 2-alkenal reductase gene cluster on Pv10 and a Pentatricopeptide repeat domain on Pv11. Bean lines utilized in the study were ranked by genomic estimated breeding values (GEBV) for disease severity, biomass, and the root architecture traits, and the observed and predicted values had high to moderate correlations. Cross validation of genomic predictions showed slightly lower correlational accuracy. Bean lines with the highest GEBV were among the most resistant, but did not necessarily rank at the very top numerically. This study provides information on the relationship of root architecture traits to root rot disease reaction. Snap bean lines with genetic merit for genomic selection were identified and may be utilized in future breeding efforts.

Potential of lucerne sowing rate to influence root development and its implications for field stand productivity

AbstractThe relationship between root morphology and productivity in lucerne (Medicago sativa L.) has been well documented, but the effect of sowing rate on root development is unclear. Results from three field experiments were analysed to address these objectives: (a) to investigate lucerne root development as a function of distance among plants, (b) to evaluate the effect of sowing rates on lucerne root traits and (c) to investigate the relationship between root traits and forage yield and yield components. A 4‐year experiment that compared spaced plants (50 × 50 cm, four plants m2) versus row seeding (12.5 cm, 700 germinated seeds m−2) revealed fast annual tap‐root diameter (TD) development in spaced plants, with about 12 mm, and three times greater TD and five times the lateral root number compared with row‐spaced plants. Three‐year field plot experiments at one site compared sowing rates of 400 versus 700 germinated seeds m−2 in less favourable soil for lucerne, and 700 versus 900 seeds m−2 in a better soil. Across experiments, higher plant density and root potential index were positively related to forage yield only when in association with better soil conditions and optimal water supply. Lower plant density offered advantages for faster root development. An effect of reduction in the sowing rate was increased stand height and increased yield in the third cut in a year with drought stress. Results show the need for investigation of effects of more precise spatial arrangement of lucerne plants to ensure optimization of root development and to enable yield benefits and drought resistance.

Genetic Variation in Root Architectural Traits in Lactuca and Their Roles in Increasing Phosphorus-Use-Efficiency in Response to Low Phosphorus Availability.

Low phosphorus (P) bioavailability in the soil and concerns over global P reserves have emphasized the need to cultivate plants that acquire and use P efficiently. Root architecture adaptation to low P can be variable depending on species or even genotypes. To assess the genetic variability of root architectural traits and their responses to low P in the Lactuca genus, we examined fourteen genotypes including wild species, ancient and commercial lettuce cultivars at low (LP, 0.1 mmol. L–1) and high P (HP, 1 mmol. L–1). Plants were grown in cylindrical pots adapted for the excavation and observation of root systems, with an inert substrate. We identified substantial genetic variation in all the investigated root traits, as well as an effect of P availability on these traits, except on the diameter of thinner roots. At low P, the main responses were a decrease in taproot diameter, an increase in taproot dominance over its laterals and an increase in the inter-branch distance. Although the genotype x P treatment effect was limited to root depth, we identified a tradeoff between the capacity to maintain a thick taproot at low P and the dominance of the taproot over its laterals. Regardless of the P level, the phosphorus-use-efficiency (PUE) varied among lettuce genotypes and was significantly correlated with total root biomass regardless of the P level. As taproot depth and maximum apical diameter were the principal determinants of total root biomass, the relative increase in PUE at low P was observed in genotypes that showed the thickest apical diameters and/or those whose maximal apical diameter was not severely decreased at low P availability. This pre-eminence of the taproot in the adaptation of Lactuca genotypes to low P contrasts with other species which rely more on lateral roots to adapt to P stress.

Pre-evaluation response of rhizosphere hybridization in acid lime

Rhizosphere hybridization is a new concept to secure the plant growth-promoting microorganisms to produce better nursery plants. Taking into the objective of rhizosphere hybridization, the present investigation was conducted in the secondary nursery block of ICAR-Central Citrus Research Institute, Nagpur. As many ten treatments consisting of rhizosphere microbes in form of water extract of the rhizosphere of acid lime, neem, bamboo, banyan and microbial consortium were tested in acid lime seedlings (cv NRCC Acid lime-7) raised on a solarized but containerized soil completely randomized design with three replications during 2018-20. Results showed a significant response to different treatments on plant growth parameters. In our study, the effect of the combined rhizosphere of banyan (Ficus benghalensis), neem (Azadirachta indica) and bamboo (Dendrocalamus strictus) was significantly superior to the rest of the treatments in increasing the biometric (seedling height, seedling diameter and number of branches per seedling), number of leaves per seedling, root architecture (tap root length, tap root diameter and number of secondary roots per seedling) and microbial biomass (fungal count and bacterial count) response of acid lime seedling compared to control treatment. Rhizosphere soil treatment was found to be superior over rhizosphere water extract treatment. Among various rhizosphere water extract treatments, acid lime rhizosphere water extract performed better in biometric response of acid lime seedling. Microbial consortium was observed to be better in increasing the microbial biomass of the rhizosphere, which could probably translate its response at later stages but added an additional resilience to rhizosphere, thereby, potentially effective in reducing the mortality once planted in main field.

Sowing configuration affects competition and persistence of lucerne (

Spatial separation of species at sowing has been proposed as a means of managing interspecific competition in mixed swards. This study examined the effect of row configuration on persistence of lucerne (Medicago sativa L.) in pastures and pasture–cover crop mixtures at three sites in the Central West, and in pasture mixtures at three sites in the Riverina, New South Wales, Australia. Lucerne density, taproot diameter, groundcover, and spatial distribution relative to the original drill row were measured at all sites, and plant-available soil water and light interception during spring were assessed at some sites. Row configuration (alternate or mixed drill rows) did not affect lucerne persistence; however, where lucerne seed was concentrated in every third drill row, intraspecific competition led to increased lucerne mortality. This was estimated to occur at densities &gt;28 plants/m drill row. A lucerne density of ~55 plants/m2 in every or alternate drill rows (at row spacings of 250 mm) would likely achieve maximum lucerne production in the semi-arid environments tested, subject to the chance event of favourable conditions in the period after sowing that would maintain that density (e.g. cumulative summer rainfall &gt;100 mm and summer day degrees &lt;2160°C in 2 years at Cowra). The presence of a cover crop in the establishment year reduced lucerne density by 39% compared with pasture only, regardless of row configuration. Changed row configuration did not reduce competition for light under a cover crop, but there was a small increase in available soil water of up to 4.9 mm in the 0–1.15 m depth, mainly during the first summer, where pasture was sown in alternate compared with mixed drill rows with a cover crop. Soil was drier in pasture-only treatments than those with a cover crop, attributable to increased lucerne density and lower levels of litter cover on the soil surface. Pasture species remained largely confined to the original drill row, especially in drier environments, highlighting the importance of narrower row spacings for pasture establishment. In addition, we determined a mathematical relationship between lucerne density and the non-destructive measure of basal frequency; this relationship could be applied in mature lucerne stands with densities ≤80 plants/m2.

Responses of four varieties of carrot plant (Daucus carota L.) grown in medium latitude to different dosages of fertilization

A study was conducted to investigate the effect of different rates of NPK fertilization on growth and yield of carrot plants in medium latitude. The experiment was undertaken in Setiling Village, Central Lombok (at ca. 650 m amsl) and arranged according to a RCBD two factors: variety (v) and dosages of NPK fertilization (n). The first factor were four carrot varieties: Gundaling (v1), Kirana (v2), New Nantes (v3) and New Kuroda (v4), while the second factor were four dosages of NPK fertilization: 50 kg/ha (r1), 100 kg/ha (r2), 200 kg/ha (r3) and 400 kg/ha (r4). The results showed that there was no interaction between carrot varieties and rate of NPK fertilization on influencing growth and yield of carrot in medium latitude. However, growth and yield of carrot in medium latitude were significantly influenced by variety and rate of NPK fertilization, as shown by differences in the ratio of above and below ground biomass, tap-root weight, tap-root diameter and the ratio between cortex and stele. Accordingly the suitable variety for cultivation in the medium latitude was Gundaling variety (v1), with a higher growth and yield were obtained by NPK fertilization at rate of 200 kg/ha (n3).