Rootstock Research Articles

Genetic analysis of village pear (Pyrus communis L.) cultivar populations in northeastern Türkiye

Abstract Pear (Pyrus communis L.) stands out as a prominent fruit species in temperate regions worldwide. The Çoruh River basin, nestled in the lower Caucasus in Türkiye, serves as a valuable repository of pear germplasm. To elucidate the genetic structure of pear populations in this region, 84 village pear cultivar genotypes (land races) from six villages, sample garden collections (SCC), and wild Panta root stock populations were analysed using eleven microsatellite markers. Genetic diversity and structure analyses indicated that village pear cultivar populations exhibit substantial genetic diversity and admixture. This diversity is attributed to local farming practices such as phenotypic selection and widespread dispersal of clonal materials. The genetic structure analysis, combined with the identification of private alleles, indicates that the pear genetic resources in the Çoruh river basin likely has originated from two gene pool sources, specifically the Meydancık and Camili village pear traditional cultivar populations. The Camili village pear cultivar population as a new in situ genetic reserve site has been proposed. Despite the existence an ex situ conservation site, the study suggests inadequateness of SCC as an ex situ site in capturing the full extent of genetic diversity of village pear cultivar genetic resources. Thus, enriching the genetic diversity in the SCC ex situ site is essential for effective pear genetic resource conservation in the Çoruh river basin. These findings contribute valuable insights for the development of targeted conservation strategies, ensuring the preservation of pear genetic resources in this region.

Theory of seed mix design with applications to ecological restoration

A major factor hindering ecological restoration is uncertainty about which plant species will best establish. We account for this uncertainty in the design of seed mixes, though our developments are relevant to other planting mixes (e.g. root stock). We view seed mixes as being comprised of one or more species groups (e.g. shrubs, grasses, and nitrogen fixers). We mathematically establish that chances of relatively low densities decline as a species group's seeding rate (e.g. 100 seeds/m2) is divided more evenly among more species. This decline is sharpest if survival probabilities vary widely among species. To determine how much survival probabilities typically vary, we studied grasses commonly seeded in Great Plains grasslands and Mediterranean annual grasslands in the western United States. Survival probabilities varied extensively, so the chances of low densities declined markedly with increasing seeded species numbers. In the Great Plains, the chances of establishment failures (0 plants/m2) were 50% when the seeding rate was allocated to one species versus 0% when the seeding rate was divided evenly among five or more species. Similarly, in Mediterranean annual grasslands, the chances of very low densities (≤1.0 plants/m2) declined from 24% when one species was seeded to 0% when three or more species were seeded. The seeding rate for each plant group should be divided as evenly as possible among as many species as practical. Compared to increasing seeding rates to provide greater densities, dividing fixed rates more evenly among more species could prove less expensive.

Soil health indicators in oil palm agroforestry systems in the eastern Amazon, Brazil

Agroforestry systems (AFSs) are generally recognized for improving soil health and increasing soil carbon (C) stock. In the Amazon region, oil palm AFSs have been promoted as a productive strategy and may offer an additional benefit of recovering degraded areas. Our objective was to evaluate whether the management practices adopted in oil palm AFSs affect soil health indicators and C stock. We carried out a study in Tomé-Açu, state of Pará, eastern Amazon, through which we evaluated two oil palm AFSs that differed in species diversity: higher diversity (AFShigh) and lower diversity (AFSlow). We used a regenerating forest (FOR) to compare with the oil palm AFSs, as regenerating forests are also a model of environmental recovery in the eastern Amazon. In the 0–10, 10–20 and 20–30 cm soil layers, we evaluated chemical indicators (active acidity (pH), calcium (Ca), magnesium (Mg), potassium (K), phosphorus (P), and aluminum (Al)), (b) physical indicators (density (SD) and stability of aggregates (AGGRE)), and (c) biological indicators (permanganate oxidizable carbon (POXC), particulate organic carbon (POC), total soil carbon (SOC content) and root stock (ROOT)). We also evaluated the total soil carbon stock (SOC stock). The values of the biological indicators in the most superficial layer, especially the C indicators, were higher in the AFSlow (C content: 1.63 ± 0.13%, POXC: 568 ± 17 mg kg−1, POC: 0.63 ± 0.10 g kg−1) and the AFShigh (C content: 1.84 ± 0.04%, POXC: 656 ± 24 mg kg−1, POC: 0.83 ± 0.06 g kg−1) than in FOR (C content: 1.35 ± 0.09%, POXC: 336 ± 10 mg kg−1, POC: 0.44 ± 0.03 g kg−1). In general, the values of chemical indicators were higher in the AFSs than in FOR, except for the Al content, which was higher in FOR than in the AFSs. The physical indicators did not show a specific pattern of variation between the AFSs and FOR; aggregate stability was higher in FOR (range throughout the soil profile: 5.57 ± 0.09 to 5.38 ± 0.24 mm) than in the AFSlow (5.41 ± 0.03 to 3.79 ± 0.07 mm) and the AFShigh (5.07 ± 0.01 to 3.79 ± 0.11 mm) in all the soil layers, and soil density was higher in the AFShigh and FOR than in the AFSlow in most subsurface layers. Therefore, oil palm AFSs improve the chemical and biological health of the soil, especially in the more superficial layers, but it does not improve the physical health of the soil when compared to the forest.

Negative effects of human disturbance and increased aridity on root biomass and nutrients along the regeneration of a tropical dry forest in the context of slash-and-burn agriculture

Biomass is an important indicator of the ability of tropical forests to deliver ecosystem services, but little attention has been given to belowground biomass and its drivers in human-modified landscapes. Here, we investigated the belowground biomass and nutrient concentration/stocks (C, P, and N) across regenerating forest stands with varying ages (10–76 years old) and old-growth forests in the Caatinga dry forest (northeastern Brazil) in the context of slash-and-burn agriculture. Belowground biomass ranged from 1.89 ± 0.33 Mg ha−1 to 17.53 ± 2.28 Mg ha−1 (mean ± SE) across regenerating forest stands and averaged 8.33 ± 1.59 Mg ha−1, with no differences compared to old-growth stands. However, regenerating stands exhibited a higher root/shoot ratio with biomass concentrated in the superficial soil layer and in large-sized roots, regardless of the successional stage. Root nutrient concentration and stocks were highly variable across forest stands with fine roots supporting a higher concentration of N and P, while regenerating stands supported lower nutrient stocks as compared to old-growth forests. Finally, precipitation and chronic disturbance emerged as the most important drivers of belowground biomass and nutrient concentrations/stocks, while aboveground biomass played a negligible role. Our results indicate that, in human-modified landscapes of tropical dry forests, belowground biomass and nutrients play important roles in ecosystem functions in regenerated forests after slash-and-burn agriculture. Forest resilience and provision of ecosystem services (e.g., nutrient cycling) appear to be very sensitive to increased aridity and exploitation of forest resources.

Assessment of genetic homogeneity of in-vitro propagated apple root stock MM 104 using ISSR and SCoT primers

Apple is an important fruit crop that is always in demand due to its commercial and nutraceutical value. Also, the requirement for quality planting material for this fruit crop for new plantations is increasing continuously. In-vitro propagation is an alternative approach, which may help to produce genetically identical high grade planting material. In this study, for the first time, an efficient and reproducible propagation protocol has been established for apple root stock MM 104 via axillary bud. Culturing axillary buds on Murashige and Skoog apple rootstock (MM 104) resulted in better in-vitro propagation. (MS) basal medium supplemented with 3.0% (w/v) sucrose and 0.8% (w/v) agar. The axillary buds were established in MS basal medium with BA (5.0 µM), NAA (1.0 µM) and further used to establish invitro propagation protocol. Plant Growth Regulators (PGRs), BA (1.0 µM) in combination with NAA (1.0 µM) was found most efficient for shoot multiplication (100%) and produced 9.8 shoots/explants with an average shoot length of (2.4 ± cm). All the shoots produced roots in 0.1 µM IBA with a 5-day dark period. Acclimatization of in-vitro raised plantlets was obtained with vermiculite: perlite: sand: soil (2:2:1:1) resulting in 76% survival under field conditions. The study showed that the use of axillary bud is efficient for multiple-shoot production of apple rootstock (MM 104). This is the first comprehensive report on in-vitro growth of apple root stock MM 104 with an assessment of genetic stability using DNA fingerprinting profiles based on Inter Simple Sequence Repeats (ISSR) and Start Codon Targeted (SCoT). The genetic stability of in-vitro-produced plants, as determined by SCoT and ISSR primers, demonstrated genetic closeness to the mother plant.

Fertility Evaluation of Temperate Farm Soils of Krishi Vigyan Kendra Doda in NW Himalayas, India

Fertility evaluation of farm soils of KVK Doda of SKUAST-Jammu (J&K) was carried out using nutrient index approach. Representative soil samples drawn from different land uses viz., HD apple orchard, apricot block, apple mother block, walnut block, apple orchard on different root stocks, nectarine block, almond block, plum block, peach block, crop cafeteria block, apple nursery block and pomegranate block were analyzed for important physico-chemical characteristics and available nutrients. These soils were sandy clay, silty clay and clay in texture with pH, EC and OC varying from 5.42 to 7.14, 0.04 to 0.30 dS/m and 5.8 to 17.6 g/kg, respectively. Contents of available N, P and K for these soils varied from 263.2 to 557.9, 2.73 to 79.0 and 63.57 to 286.72 kg/ha, respectively whereas; available S, Mn, Fe, Zn, Cu and B varied from 2.15 to 17.23, 6.93 to 55.40, 4.0 to 19.60, 0.16 to 2.48, 0.42 to 4.34 and 0.07 to 0.74 mg/kg, respectively. As per NI values, these soils fell in high category of available Mn, Fe, Zn and Cu; medium category of available N, P, K and B: and low category of available S. Soil pH was significantly and negatively correlated with OC, EC, available N, P, Mn and Fe. Soil EC had significant positive correlation with OC, available N, P, K, S, Mn, Fe and Zn. Further, OC and available N showed significant positive correlation with each other as well as with available S, Mn, Fe and Zn. Available P showed strong synergistic relationships with available K and Mn. Also, available K, S and Mn were significantly positively correlated with each other. Further, available Zn was also significantly positively correlated to available K, Mn and B while its correlation with available Cu was significantly negative. Available Fe was significantly and positively correlated to available S and Mn. Regression analysis indicated 97.7% contribution of OC towards total variability in available N. About 67 and 33% of total variability in available P and S, in order, could be attributed to OC and EC together; while nearly 46% of that in available Fe could be attributed to pH and OC together. Nearly 34 and 57% of total variability in available Zn and K, in order, could be attributed to pH and EC together. EC alone could explain about 60% of total variability in available Mn.

Age‐related changes in root dynamics of a novel perennial grain crop

AbstractBackgroundStanding root biomass stocks are larger in the perennial grain intermediate wheatgrass (IWG; Thinopyrum intermedium [Host] Barkworth and Dewey) than annual spring wheat (Triticum aestivum L.). However, previous studies have not separated root growth from root decomposition, which presents a significant gap in our understanding of how roots can contribute to soil organic carbon (C) accrual or other soil properties through time.MethodsWe used paired sequential coring and root ingrowth cores to measure standing root stock, new root production, root decomposition, and decomposed root C and N from 0 to 15 cm soil depth of 1‐year‐old IWG (IWG‐1), 2‐year‐old IWG (IWG‐2), and annual spring wheat.ResultsStanding root stock was 3.2–6.5 and 6.3–9.9 times higher in IWG‐1 and IWG‐2 than wheat. Total root production was 1.7 times greater in IWG‐1 than IWG‐2. Conversely, root decomposition almost doubled from 1.39 to 2.43 kg m−3 between IWG‐1 and IWG‐2.ConclusionsIn IWG, decreased root production and increased root decomposition with stand age suggest a change in growth strategy that could reduce the contribution of root‐derived C to stabilized soil C pools as IWG stands age.

Breeding approaches for improvement of temperate fruit crops and nuts - a review

Fruit breeding is an ancient technology with dynamic current technology and an exciting future (Janick and Moore, 1975, 1996). In its broadest sense, fruit breeding refers to the purposeful genetic improvement of fruit crops through various techniques including selection, hybridization, mutation induction, and molecular techniques. Its origins trace to the domestication process in prehistory and antiquity, where useful species were chosen and cultivated, and improved by continuous selection (Janick, 2005, 2011). Much of the world fruit industry is still based on grower selection from chance seedlings as well as mutations (sports) and as a result many fruit species are characterized by a narrow germplasm base. Spontaneous hybridization between wild plants and cultivated clones was critical to the early domestication of fruits. The lengthy juvenile period and the large field space required to grow temperate fruits have imposed major limitations on conventional breeding and various molecular biological techniques have been employed to make fruit breeding easier. (Igarashi et al.2016). Marker-assisted selection (MAS) uses DNA markers to provide an early DNA-based evaluation of genetic performance potential of seedlings, with the aim of improving cost and/or genetic efficiency of seedling selection (Ru, et al., 2015). Transgenic technology has facilitated the development of fruit trees with resistance to fungal or bacterial diseases, improved fruit quality, or root stocks with better rooting or dwarfing ability. In recent years, new technologies for genetic improvement, such as transgrafting, and genome-editing, have emerged. (Mudge, et al. 2009; Jia and Wang 2014). Using these techniques, no foreign genes are present in the final product, and some of them show considerable promise for application to apple breeding. Furthermore, genome editing, by which only the target gene can be accurately modified, is emerging as a novel breeding technology. These new technologies will undoubtedly facilitate fruit breeding, and yield novel and attractive fruit cultivars.

Tracing carbon and nitrogen reserve remobilization during spring leaf flush and growth following defoliation.

Woody plants rely on the remobilization of carbon (C) and nitrogen (N) reserves to support growth and survival when resource demand exceeds supply at seasonally predictable times like spring leaf flush and following unpredictable disturbances like defoliation. However, we have a poor understanding of how reserves are regulated and whether distance between source and sink tissues affects remobilization. This leads to uncertainty about which reserves-and how much-are available to support plant functions like leaf growth. To better understand the source of remobilized reserves and constraints on their allocation, we created aspen saplings with organ-specific labeled reserves by using stable isotopes (13C,15N) and grafting unlabeled or labeled stems to labeled or unlabeled root stocks. We first determined which organs had imported root or stem-derived C and N reserves after spring leaf flush. We then further tested spatial and temporal variation in reserve remobilization and import by comparing 1) upper and lower canopy leaves, 2) early and late leaves, and 3) early flush and re-flush leaves after defoliation. During spring flush, remobilized root C and N reserves were preferentially allocated to sinks closer to the reserve source (i.e., lower vs upper canopy leaves). However, the reduced import of 13C in late versus early leaves indicates reliance on C reserves declined over time. Following defoliation, re-flush leaves imported the same proportion of root N as spring flush leaves, but they imported a lower proportion of root C. This lower import of reserve C suggests that, after defoliation, leaf re-flush rely more heavily on current photosynthate, which may explain the reduced leaf mass recovery of re-flush canopies (31% of initial leaf mass). The reduced reliance on reserves occurred even though roots retained significant starch concentrations (~5% dry wt), suggesting aspen prioritizes the maintenance of root reserves at the expense of fast canopy recovery.

BIOLOGICALLY ACTIVE SUBSTANCES OF ANNUAL VEGETATIVE SHOOTS OF THE ROOT STOCK OF WILD SYRINGA VULGARIS L.

Syringin and oleuropein were identified in annual vegetative shoots of the root stock of wild Syringa vulgaris L. in various phases of vegetation by high-performance liquid chromatography. The maximum amount of syringin occurs during the fruit ripening phase (specific content 15.0 ± 0.2%). The maximum amount of oleuropein was found in the phase of complete lignification of vegetative shoots (specific content 16.7±1.6%). Harvesting of annual vegetative shoots of the root stock of wild Syringa vulgaris L. is advisable to carry out in the fruit ripening phase (September) and in the phase of complete lignification of vegetative shoots (July). Annual vegetative shoots of Syringa vulgaris L. can be recommended to be used as a promising raw material source of syringin and oleuropein, for the development of domestic therapeutic and prophylactic agents.

Angas-Sura etymologies XIII

The paper as part of a long-running series is devoted to the etymological analysis of a new segment (namely that with initial dental *d-) of the Angas-Sura root stock, a small group of modern languages remotely and ultimately akin to pharaonic Egyptian and the well-known Semitic languages or Twareg in the Sahara etc. Doing so, I wish to continue the noble tradition initiated by J.H. Greenberg (1958), the founding father of modern Afro-Asiatic comparative linguistics (along with I.M. Diakonoff), who was the first scholar ever to have established by Neo-Grammarian the methods regular consonantal correspondences between Angas-Sura (AS) and ancient Egyptian in his pioneering (painfully isolated) paper on the ancient trichotomy of the word-initial labials in both branches. Nowadays our chances in following this path are substantially more favourable being equipped with our gigantic comparative root catalogue system of the Egyptian etymologies ever published (ongoing since 1994) and of the Afro-Asiatic parental lexical stock (ongoing since 1999). This series of papers represents the author’s ongoing project for an etymological dictionary of the Angas-Sura languages comprising their entire Afro-Asiatic cognacy.

MORPHOLOGICAL CHARACTERISTIC OF VIERUL LOCAL GRAPE (Vitis spp.) CUTTING SEEDS ON PODZOLIC SOIL USING VARIOUS CONCENTRATION OF AUXIN SOAK

The development of grapes (Vitis vinifera) has obstacle among others are limited optimal land and difficult nurseries. Suboptimal land use for grape cuttings can use red yellow podzolic soil (ultisol). Podzolic soil has an acidic pH and low macro and micro nutrient uptake but can still be used as a growing medium. Vierul local grapes are a type of grape that has begun to be developed as root stock in nurseries but needs to be improved for its root success using a synthetic phytohormones bath of napthaline acetic acid (NAA). The purpose of this study was to determine the morphological character of vierul local grape cuttings at various concentrations of NAAsoaking in podzolic soil growing medium. This research has been carried out in a screen house from August to December 2021. This study used a non-factorial completely randomized design (CRD) with 3 treatments and 3 replications as block consisting of F0, F1, F2, F4 following by 0, 2, 4, 6 g L-1 respectively. The morphological characteristics observed is number of bud break, time of leaves appear, number of leaves, tendril length and percentage of live cuttings. The results of the study were analyzed using ANOVA at the 5% level and continued using the DMRT at the 5% level. The result showed that soaking of NAA at a concentration of 0 g L-1 (F0) had the best result for the variable number of bud break and number of leaves. Concentration of 6 g L-1 (F3) had the best result for variable length of the tendril while for the variable when the leaves appear, NAA soaking has no significant effect. The percentage of live cuttings is still low because it is influenced by the quality (material) of cuttings, the age of woodstock, growing media and water availability.

Advanced modeling and optimizing for surface sterilization process of grape vine (Vitis vinifera) root stock 3309C through response surface, artificial neural network, and genetic algorithm techniques

In vitro, sterilization is one of the key components for proceeding with plant tissue cultures. Since the effectiveness of sterilization has a direct impact on the culture's final outcomes, there is a crucial need for optimization of the sterilization process. However, compared with traditional optimizing methods, the use of computational approaches through artificial intelligence-based process modeling and optimization algorithms provides a precise optimal condition for in vitro culturing. This study aimed to optimise in vitro sterilization of grape rootstock 3309C using RSM, ANN, and genetic algorithm (GA) techniques. In this context, two output responses, namely, Clean Culture and Explant Viability, were optimised using the models developed by RSM and ANN, followed by a GA, to obtain a globally optimal solution. The most influential independent factors, such as HgCl2, NaOCl, AgNO3, and immersion time, were considered input variables. The significance of the developed models was investigated with statistical and non-statistical techniques and was optimised to determine the significance of selected inputs. The optimal clean culture of 91%, and the explant viability of 89% can be obtained from 1.62% NaOCl at a 13.96 min immersion time, according to MLP-NSGAII. Sensitivity analysis revealed that the clean culture and explant viability were less sensitive to AgNO3 and more sensitive to immersion time. Results showed that the differences between the GA predicted and validation data were significant after the performance validation of predicted and optimised sterilising agents with immersion time combinations were tested. In general, GA, a potent methodology, may open the door to the development of new computational methods in plant tissue culture.

Inoculation of rose (Rosa rubiginosa L., eglantine or the briar rose) flower root stocks with consortia of endophytic bacteria and arbuscular mycorrhizal fungi improves its establishment and success rate under greenhouse conditions

Rhizospheric microorganisms can be used to reduce synthetic fertilizer applications. We tested the efficiency of a consortium of arbuscular mycorrhizae and two rhizobacteria on rose (Rosa rubiginosa) production in the greenhouse. The experimental organisms were two strains of Acinetobacter soli (AU4, RG5), and Glomus sp1. The treatments consisted of, T1-negative control; T2-positive control; T3-AU4; T4-RG5; T5-AU4 + RG5; T6-AU4 + Glomus sp.1; T7-RG5 + Glomus sp.1; T8-AU4 + RG5 + Glomus sp.1. The design was complete randomized design with three replications. The highest percentage of rose root stock establishment increment was exhibited by AU4 + RG5 + Glomus sp.1 consortia inoculation (90.5%) followed by dual inoculation of AU4 + RG5 (59.5%) compared to the negative control. In conclusion, inoculation of rose flower root stocks with plant growth promoting microorganisms improved the root stock establishment.

Dwarfism in Fruit Plants: A Review

In this modern era, farmers are adopting high density planting (HDP) for most of the fruit crops. Dwarfing is based on the principle of making the optimal use of vertical and horizontal space per unit time and harnessing the highest potential returns per unit of inputs and natural resources. Dwarfing in fruit crops can be accomplished through a variety of methods, including the use of dwarfing rootstock, the selection of spur type scion cultivars, use of interstock, pruning, root pruning, various training systems, girdling, scoring, bark invasion and the application of growth retardants. One strategy for promoting early fruiting, less vigour and increasing production is to utilize dwarf root stocks. The mechanism underlying dwarfing involves anatomical, physiological and biochemical changes. It has been proposed that dwarfing rootstock or interstock control tree size by regulating the auxin that passes through the rootstock or interstock’s bark. Paclobutrazol retards growth, shoot elongation and reduced internodal length by inhibiting gibberellins synthesis. Dwarfness can be imparted by the using incompatible rootstock. Dwarfing can be induced by inducing viral infection, although, it is not commercially adopted. Recombinant DNA technology has recently expanded the gene pool that can be managed to cause dwarfism and maximize benefits in horticulture crops.

Fine-resolution global maps of root biomass carbon colonized by arbuscular and ectomycorrhizal fungi

Despite the recognized importance of mycorrhizal associations in ecosystem functioning, the actual abundance patterns of mycorrhizal fungi belowground are still unknown. This information is key for better quantification of mycorrhizal impacts on ecosystem processes and for incorporating mycorrhizal pathways into global biogeochemical models. Here we present the first high-resolution maps of fine root stocks colonized by arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) fungi (MgC ha−1). The maps were assembled by combining multiple open-source databases holding information on root biomass carbon, the proportion of AM and EcM tree biomass, plot-level relative abundance of plant species and intensity of AM and EcM root colonization. We calculated root-associated AM and EcM abundance in 881 spatial units, defined as the combination of ecoregions and land cover types across six continents. The highest AM abundances are observed in the (sub-)tropics, while the highest EcM abundances occur in the taiga regions. These maps serve as a basis for future research where continuous spatial estimates of root mycorrhizal stocks are needed.

Germination and Graft Compatibilty Study of Wild Solanum spp and Brinjal Root Stocks with Tomato Scions

The experiment was conducted at Central Horticultural Experiment Station, ICAR- IIHR, Aiginia, Bhubaneswar, Odisha, India during kharif seasons of 2018 in collaboration with Odisha University of Agriculture and Technology, Bhubaneswar, to study the seed germination, days taken to reach grafting stage and grafting success (percentage) of rootstock and scion seeds used for grafting. The cultivated and wild species of brinjal and tomato were used as rootstocks with tomato Arka Rakshak F1 hybrid as scion. The experiment was conducted with 13 root stocks following statistical design CRD with three replications in pro trays to find out better root stock for grafting. A significant difference was recorded for the rootstock and scion parameters. Utkal Anushree had taken minimum number of days (6.67 days) for germination and the wild Solanum torvum had taken maximum number of days (16.67 days) to germinate, On the other hand, Arka Rakshak took least number of days (34.33 days) to reach grafting stage while the wild Solanum torvum reached to grafting stage within 56 days. The grafting success percentage ranged from 74.67 to 96 percent. Maximum grafting success (%) was recorded in Solanum torvum whereas minimum grafting success (%) was observed in S. sisymbriifolium wild solanum spp. root stock.

Spatial and temporal electrical resistivity dynamics in a dense Ultisol under deep tillage and different citrus root-stocks

Deep tillage can be applied to face high-density soil horizons by improving the root system’s access to deeper layers. In this sense, soil and ecosystem services related to nutrients cycling and water recharge can be improved. In this study, the spatial and temporal dynamics of soil water content (θ) were inferred using two-dimensional electrical resistivity (ER) surveys, that were applied to explore the soil profile treated by deep tillage under different citrus rootstocks (RS) implantation. A seasonal scale ER monitoring (Spring 2018, Summer 2019, and Winter 2019) was carried out at a selected study area, characterized by Ultisols and located in Southeastern Brazil. Three different citrus RS-types, represented by the varieties ‘Cravo Santa Cruz lemon’ (CSC), ‘Sunki Tropical Tangerine’ (ST), and ‘Citrandarin Indio’ (CI). Deep tillage was adopted before RS citrus-types planting by opening furrows and subsoiling up to 0.6 m depth. The interrows citrus plants were covered with Brachiaria decumbens (Syn. Urochloa) in all citrus RS-type plots. A native forest area (‘Forest’) was used as reference for all θ evaluations. The model for the ER-θ relationships was determined from measurements conducted on soil samples in the laboratory. Root water uptake (RWU), in terms of θ changes, was evaluated at the different treatments under study. The obtained results proved the suitability of ER method for identifying the ER-θ dynamics in the Ultisol profiles over time. Lower and more stable θ values were obtained in the ‘Forest’ and interrow areas. Among the evaluated citrus RS-types, CSC showed the highest water use efficiency due to the greatest root system development.

The inverted forest: Aboveground and notably large belowground carbon stocks and their drivers in Brazilian savannas

Savannas contribute to ca. 30 % of the total terrestrial net primary productivity and are responsible for significant carbon storage. Savannas in South America are mostly found within the Cerrado Domain, which is very threatened and presents remarkable carbon pools. Herein, we used a unique dataset of 21 Cerrado sites spanning 144 permanent field plots in Southeastern Brazil to assess the general patterns of above and belowground carbon stocks. We identified the main environmental and tree diversity drivers of aboveground wood carbon and productivity, belowground carbon stocks (roots and soil), carbon ratios (root:shoot and above:below) and total carbon stocks in the Cerrado through a combination of climatic estimates, fire frequency data, field measurements of vegetation, roots, soil carbon, nutrients and texture, and assessment of different components of diversity (species, functional and phylogenetic). Our findings reveal average aboveground, root, and soil carbon stocks of 20.4, 14.24, and 123.13 Mg.ha−1, respectively. Average Root:Shoot and Above:Below confirm the “inverted forest” concept with values of 1.58 and 0.21, respectively. Total carbon was 145.62 Mg.ha−1, reinforcing the great amount of carbon storage in the Cerrado and its role in the carbon cycle and dynamics. Tree diversity variables (mainly species diversity and functional composition variables) had more significant effects over aboveground variables, whereas environmental variables had more significant effects over belowground variables. Ratios and total carbon mixed up these effects. The impressive values of carbon storage, especially belowground, point out the need to better manage and protect the Cerrado. Moreover, our findings might be particularly relevant for discussions on restoration programs focused on the trees-for‑carbon idea that do not consider species diversity and belowground carbon stocks.

Screening of Promising Rootstocks Against Phytophthora Root Rot in Citrus

Citrus root rot caused by Phytophthora parasitica var. nicotianae is the most damaging disease in citrus cultivation in Maharashtra’s Vidarbha region. To overcome the damage caused by this disease, tolerant/resistant rootstocks must be selected. In present study, twelve varied root stocks were tested in sick pot condition to determine tolerance/resistance against Phytophthora nicotianae during 2020-21 by inoculating 6 month old seedlings with a 20 ml spore suspension (108 cfu/ml) of P. nicotianae per pot. Disease incidence, feeder root rot index, percent leaf fall and Phytophthora population density were all assessed six weeks after inoculation. The response of root stocks to the tested pathogen varied. The minimum per cent root rot incidence (4.44 %) and feeder root rot (0.63) was observed in Alemow (C. macrophylla) while maximum root rot incidence (28.89%) and feeder root rot (3.20) was noticed in susceptible check Rough lemon (Citrus jambheri). Rangpur lime Akola had the highest seedling height (28.43 cm), while root stock CRH-12 had the lowest (21.07 cm). The results showed that there were no significant differences in the population density of Phytophthora cfu/cc soil in the tested root stocks. It is thought that the rootstock Alemowisinvolvedin citrusplant tolerantto P. nicotianae.