Rootstock Grafting Research Articles

Resistance of mango cultivar Ubá to Ceratocystis fimbriata depends on the pathogen's physiological variability

Mango sudden decline (MSD) caused by Ceratocystis fimbriata is one of the major diseases affecting mango crop in Brazil, Oman, and Pakistan. In Brazil, the main strategy for MSD management has been the use of resistant plants as rootstock for grafting. In this study, we tested the resistance of mango cultivar Ubá to C. fimbriata isolates from different populations. Firstly, we inoculated 2173 seedlings from 129 accessions of mango cv. Ubá using three representative fungal isolates from Brazil. Following the inoculation, the potential resistant plants were challenged against ten C. fimbriata isolates from Brazil and three from Oman. Finally, to confirm its resistance, clonal replicates of the resistant accessions were re-inoculated with the same fungal isolates. In the first selection, 13 accessions were pre-selected as resistant. In subsequent selections, they proved to be resistant to C. fimbriata isolates from populations from Oman/Pakistan and Southeastern Brazil. However, all 13 accessions were susceptible to fungal isolates from populations from Northeastern Brazil and Rio de Janeiro (also in Brazil). Our results reveal that mango cv. Ubá resistance to MSD is isolate specific and depends on the pathogen population. We obtained 13 mango cv. Ubá clones resistant to C. fimbriata, which may be useful as rootstock to MSD management in Oman and specific regions from Brazil.

Evaluation of Different Bacterial Wilt Resistant Eggplant Rootstocks for Grafting Tomato.

Bacterial wilt (BW) is one of the most economically important diseases of tomato and eggplant in the tropics and subtropics, and grafting onto resistant rootstocks can provide an alternative and effective solution to manage soil-borne bacterial in these crops. This study was conducted to evaluate the BW resistance and agronomic potential of newly identified eggplant accessions as rootstocks for tomato grafting. Five BW resistant eggplant accessions (VI041809A, VI041943, VI041945, VI041979A, and VI041984) from the World Vegetable Center were evaluated as rootstocks for grafting with two different fresh market tomato cultivars (Victoria and TStarE) as scion under open field conditions in Taiwan. Graft compatibility using the tube grafting method as well as BW wilting percentage, disease index, fruit yield and quality parameters were assessed. All the rootstocks showed good graft compatibility (93% and above) and grafted plants showed low wilting percentage (0.0–20.0%) and disease index (0.0–20.8%) following inoculation with BW. Yield for the eggplant rootstock grafted tomato plants was higher compared to the non-grafted tomatoes and self-grafted tomato. Fruit quality was not affected by grafting, although some differences in antioxidant activities were observed. The new eggplant rootstocks can be considered as alternatives to the rootstocks currently used for commercial production of tomatoes during the hot-wet season.

New Sources of Resistance in Winter Squash (Cucurbita moschata) to Phytophthora Crown Rot and Their Relationship to Cultivated Squash

Butternut squash (Cucurbita moschata) is an important vegetable crop grown and consumed in most states in the United States. C. moschata lines and interspecific hybrids between Cucurbita species are also used as rootstocks for grafting watermelon and melon. However, currently most commercially available C. moschata squash varieties are highly susceptible to crown and root rot caused by the oomycete pathogen Phytophthora capsici, especially in the southeastern United States. All available plant introductions (PIs) of C. moschata (319 PIs) were evaluated for resistance to crown rot. Four-week-old plants were inoculated with 104 zoospores from a local South Carolina isolate of P. capsici. Plants were rated for disease severity 3 weeks after inoculation using a 0 to 5 rating scale (0 = no symptoms and 5 = plant dead). The majority (87%) of the C. moschata PIs were highly susceptible to crown rot in the first evaluation and were rated as 5. Reevaluation of the promising PIs identified several potential new sources of resistance (e.g., Grif 935, PI 442272, PI 442264, PI 512142, PI 438724, PI 438778, and PI 442280). Variability in resistance reaction among plants within a PI was also observed, and not all plants exhibited resistance. Further evaluation of S1 generation from the most resistant plants (rated ≤1) demonstrated that highly resistant plants could be selected from these PIs to develop lines for use in breeding programs. These new sources of resistance can be utilized for developing new crown and root rot resistant rootstocks for watermelon grafting and for developing resistant varieties for human consumption.

Effect of Transgenic Rootstock Grafting on the Omics Profiles in Tomato.

Grafting of non-transgenic scion onto genetically modified (GM) rootstocks provides superior agronomic traits in the GM rootstock, and excellent fruits can be produced for consumption. In such grafted plants, the scion does not contain any foreign genes, but the fruit itself is likely to be influenced directly or indirectly by the foreign genes in the rootstock. Before market release of such fruit products, the effects of grafting onto GM rootstocks should be determined from the perspective of safety use. Here, we evaluated the effects of a transgene encoding β-glucuronidase (GUS) on the grafted tomato fruits as a model case. An edible tomato cultivar, Stella Mini Tomato, was grafted onto GM Micro-Tom tomato plants that had been transformed with the GUS gene. The grafted plants showed no difference in their fruit development rate and fresh weight regardless of the presence or absence of the GUS gene in the rootstock. The fruit samples were subjected to transcriptome (NGS-illumina), proteome (shotgun LC-MS/MS), metabolome (LC-ESI-MS and GC-EI-MS), and general food ingredient analyses. In addition, differentially detected items were identified between the grafted plants onto rootstocks with or without transgenes (more than two-fold). The transcriptome analysis detected approximately 18,500 expressed genes on average, and only 6 genes were identified as differentially expressed. Principal component analysis of 2,442 peaks for peptides in proteome profiles showed no significant differences. In the LC-ESI-MS and GC-EI-MS analyses, a total of 93 peak groups and 114 peak groups were identified, respectively, and only 2 peak groups showed more than two-fold differences. The general food ingredient analysis showed no significant differences in the fruits of Stella scions between GM and non-GM Micro-Tom rootstocks. These multiple omics data showed that grafting on the rootstock harboring the GUS transgene did not induce any genetic or metabolic variation in the scion.

Bitter Melon (Momordica charantia L.) Rootstock Improves the Heat Tolerance of Cucumber by Regulating Photosynthetic and Antioxidant Defense Pathways.

High temperature is considered a critical abiotic stressor that is increasing continuously, which is severely affecting plant growth and development. The use of heat-resistant rootstock grafting is a viable technique that is practiced globally to improve plant resistance towards abiotic stresses. In this experiment, we explored the efficacy of bitter melon rootstock and how it regulates photosynthesis and the antioxidant defense system to alleviate heat stress (42 °C/32 °C) in cucumber. Our results revealed that bitter-melon-grafted seedlings significantly relieved heat-induced growth inhibition and photoinhibition, maintained better photosynthesis activity, and accumulated a greater biomass than self-grafted seedlings. We measured the endogenous polyamine and hydrogen peroxide (H2O2) contents to determine the inherent mechanism responsible for these effects, and the results showed that heat stress induced a transient increase in polyamines and H2O2 in the inner courtyard of grafted seedlings. This increment was greater and more robust in bitter-melon-grafted seedlings. In addition, the use of polyamine synthesis inhibitors MGBG (methylglyoxal bis-guanylhydrazone) and D-Arg (D-arginine), further confirmed that the production of H2O2 under heat stress is mediated by the accumulation of endogenous polyamines. Moreover, compared with other treatments, the bitter-melon-grafted seedlings maintained high levels of antioxidant enzyme activity under high temperature conditions. However, these activities were significantly inhibited by polyamine synthesis inhibitors and H2O2 scavengers (dimethylthiourea, DMTU), indicating that bitter melon rootstock not only maintained better photosynthetic activity under conditions of high temperature stress but also mediated the production of H2O2 through the regulation of the high level of endogenous polyamines, thereby boosting the antioxidant defense system and comprehensively improving the heat tolerance of cucumber seedlings. Taken together, these results indicate that grafting with a resistant cultivar is a promising alternative tool for reducing stress-induced damage.

Transcriptome Analysis Reveals the Different Response to Toxic Stress in Rootstock Grafted and Non-Grafted Cucumber Seedlings.

Autotoxicity of root exudates is one of the main reasons for consecutive monoculture problem (CMP) in cucumber under greenhouse cultivation. Rootstock grafting may improve the tolerance of cucumber plants to autotoxic stress. To verify the enhanced tolerance to autotoxic stress and illuminate relevant molecular mechanism, a transcriptomic comparative analysis was performed between rootstock grafted (RG) and non-grafted (NG) cucumber plants by a simulation of exogenous cinnamic acid (CA). The present study confirmed that relatively stable plant growth, biomass accumulation, chlorophyll content, and photosynthesis was observed in RG than NG under CA stress. We identified 3647 and 2691 differentially expressed genes (DEGs) in NG and RG cucumber plants when compared to respective control, and gene expression patterns of RNA-seq was confirmed by qRT-PCR. Functional annotations revealed that DEGs response to CA stress were enriched in pathways of plant hormone signal transduction, MAPK signaling pathway, phenylalanine metabolism, and plant-pathogen interaction. Interestingly, the significantly enriched pathway of photosynthesis-related, carbon and nitrogen metabolism only identified in NG, and most of DEGs were down-regulated. However, most of photosynthesis, Calvin cycle, glycolysis, TCA cycle, and nitrogen metabolism-related DEGs exhibited not or slightly down-regulated in RG. In addition, several stress-related transcription factor families of AP2/ERF, bHLH, bZIP, MYB. and NAC were uniquely triggered in the grafted cucumbers. Overall, the results of this study suggest that rootstock grafting improve the tolerance of cucumber plants to autotoxic stress by mediating down-regulation of photosynthesis, carbon, and nitrogen metabolism-related DEGs and activating the function of stress-related transcription factor. The transcriptome dataset provides an extensive sequence resource for further studies of autotoxic mechanism at molecular level.

Design and optimization on rootstock cutting mechanism of grafting robot for cucurbit

Cutting mechanisms in existing grafting machines are unable to completely cut through the rootstock growth point and can easily damage seedlings. During the mechanical operation of splice grafting, the cutting angle of the rootstock is an essential factor for ensuring the quality and survival rate of grafting seedlings and a stable process for grafting robots. Therefore, in this study, commonly used grafting rootstocks, e.g., cucurbita moschata, and calabash gourd were used as research objects for studying and analyzing the cutting angle of a splice grafting method. The morphological and structural parameters of the rootstock and scion were measured, and a structural model of the internal cavity of the rootstock was constructed using an image analysis method. The critical cutting angles for the cucurbita moschata and calabash gourd seedlings were obtained. According to the analysis, the grafting cutting angles for cucumber seedlings matching with cucurbita moschata seedlings were 20° and 25°, respectively, and the fitting rate of the cutting surface of the rootstock and scion was 99.04%. A cutting mechanism for the rootstock growth point and geometric model of the cutting operation were established, and the structural parameters of the mechanism and cutting angle adjustment were optimized. A cutting performance test showed that the success rate of the pressing the cotyledons of cucurbita moschata seedlings was 96.67%, and the success rate of cutting was 98%. The cutting accuracy was 96.8%, and the cutting surface fitting rate of the rootstock and scion was 98.61%. The latter differed by 0.43% from the theoretical rate but met the requirements for the splice grafting method. Thus, this study can provide a reference for the design of a cutting mechanism for a grafting robot. Keywords: grafting robot, rootstock cavity, cutting angle, matched grafting, parameter optimization, cucurbit DOI: 10.25165/j.ijabe.20201305.5803 Citation: Jiang K, Zhang Q, Chen L P, Guo W Z, Zheng W G. Design and optimization on rootstock cutting mechanism of grafting robot for cucurbit. Int J Agric & Biol Eng, 2020; 13(5): 117–124.

Influence of storage methods and phytochrome activities on seed germination in jackfruit seeds (<em>Artocarpus heterophyllus</em> Lam.)

Jackfruit (Artocarpus heterophyllus Lam.) is a rainfed tropical crop in coastal warm and humid climate of India. Though the softwood grafting method is standardized for rapid multiplication nevertheless, due to recalcitrant nature of jackfruit seeds obtaining rootstock for grafting throughout the year is the main constraint. Loss of seed viability in very short period during storage imposes a problem in germination. Storage conditions which prevent water loss are useful for prolonging viability of recalcitrant seeds. Hence, an experiment was undertaken during the year 2017-18 to study seed viability under different storage methods at College of Horticulture, Mulde Tal. Kudal, Dist. Sindhudurg. The experiment consists of eight storage methods and six storage period in factorial randomised block design with two replications. Hundred seeds per treatment per replication was the unit. The study revealed that the process of germination was under the control of phytochrome action and clearly indicated that the conditions of darkness and humidity are essentials for preventing moisture loss and promotion of germination. Storage of seed ether in screw cap bottle or in earthen pot buried in soil was the best for preventing the desiccation and prolonging the seed viability for 150 days. In this context storing the seeds in screw cap bottle appear to be most appropriate where there is no risk of germination of seed within storage container and seeds are kept viable beyond 150 days.

Grafting alleviates potassium stress and improves growth in tobacco

BackgroundPotassium is a nutrient element necessary for tobacco growth. Tobacco leaves with high potassium content are elastic and tough, rich in oil. And the same time, potassium can also improve the scent and aromatic value of flue-cured tobacco by regulating the synthesis of aromatic hydrocarbons in leaves.. It is an important quality indicator for flue-cured tobacco. However, the potassium concentration in tobacco leaves in most areas of China is generally lower than the global standard for high quality tobacco. Two tobacco genotypes were grafted to each other under different potassium levels to test whether potassium content and plant growth can be improved by grafting in tobacco.ResultsThe growth of tobacco in all treatments was inhibited under potassium starvation, and grafting significantly alleviated this potassium stress in ‘Yunyan 87’. The trends in whole plant K+ uptake and K+ transfer efficiency to the leaves corresponded to the growth results of the different grafts. The nutrient depletion test results showed that the roots of ‘Wufeng No.2’ had higher K+ absorption potential, K+ affinity, and K+ inward flow rate. K+ enrichment circles appeared at the endoderm of the root section in the energy dispersive X-ray figure, indicating that the formation of Casparian strips may be partly responsible for the lower rate of lateral movement of K+ in the roots of ‘Yunyan 87’. Gene expression analysis suggested that energy redistribution at the whole plant level might constitute one strategy for coping with potassium starvation. The feedback regulation effects between scion ‘Wufeng No.2’ and rootstock ‘Yunyan 87’ indicated that the transmission of certain signaling substances had occurred during grafting.Conclusions‘Wufeng No.2’ tobacco rootstock grafting can increase the K+ uptake and transport efficiency of ‘Yunyan 87’ and enhance plant growth under potassium stress. The physiological mechanism of the improved performance of grafted tobacco is related to higher K+ uptake and utilization ability, improved xylem K+ loading capacity, and up-regulated expression of genes related to energy supply systems.

Root-growth Characteristics Contributing to Genotypic Variation in Nitrogen Efficiency of Bottle Gourd and Rootstock Potential for Watermelon.

In this study, two hydroponic experiments were conducted in nutrient solution growth system. Experiments were conducted in growth chamber of Erciyes University, Agricultural Faculty in Kayseri, Turkey. In the first experiment, 10 local Turkish bottle gourd genotypes and two commercial watermelon cultivars were screened under 2 N doses (0.3 mM and 3.0 mM N) in RBD design with three replications for six weeks. In the second experiment, four genotypes (N-efficient: 70-07 and 07-45, N-inefficient: 35-10 and 45-07) were selected and used as rootstock for grafting with N-inefficient watermelon cultivar (Crimson Sweet) under 2 N doses. The grafted N-efficient gourd genotypes (07-45 and 70-07) significantly contributed to growth and biomass production of the N-inefficient watermelon plants as compared to non-grafted control plants and thus showed a higher rootstock potential for watermelon. The N-efficiency of some gourd genotypes was associated with vigor root growth and active root system particularly at low N conditions. These traits could be useful characters to select ‘N-efficient’ bottle gourd rootstocks for sustainable agriculture in the future.

Micropropagation of Prunus scoparia, a Suitable Rootstock for Almond under Drought Conditions

ABSTRACTPrunus scoparia is a wild deciduous shrub, usually living on dry calcareous soils of the rocky mountains and has been used as a grafting rootstock for domesticated almonds to provide drought resistance. In the current study, micropropagation ability of P. scoparia was investigated using cytokinin and auxin. Uniform nodal shoot pieces (3–5 cm in length) of seedlings were used as explants. The explants were disinfected with 10% sodium hypochlorite solution. For adventitious shoot induction and proliferation, Murashige and Skoog (MS) media containing 7.00 g/l agar and 30.00 g/l sucrose containing five concentrations of benzyl adenine (BA) (0.00, 0.50, 1.00, 2.00, and 4.00 mg/1) and also containing six concentrations of Thidiazuron (TDZ) (0.00, 0.50, 1.00, 2.00, 5.00, and 7.00 mg/1) were compared. For rooting, in vitro shoots (2–3 cm) were transferred into ½ MS medium supplemented with 30 g/l sucrose, 7.50 g/l agar, and different concentrations of IBA (0.00, 0.25, 0.50, and 1.00 mg/l) and NAA (0.00, 0.25, 0.50, and 1.00 mg/l). Based on the results obtained for shoot proliferation, only 2.00 and 4.00 mg/l BA and 2.00 mg/l TDZ concentrations generated shoots, while other treatments did not show shoot proliferation. Among the three treatments that generated shoots, the best results for shoot number, leaf number, and leaf color quality were observed in media containing 2.00 mg/l TDZ. Based on the results obtained for rooting, the effect of IBA concentrations on the rooting percentage, root number, and root length was significant. Among IBA concentrations, only 0.50 mg/l IBA induced rooting, while there was no rooting in the media containing other IBA concentrations. None of the NAA concentrations showed rooting. In conclusion, MS culture medium supplemented with 2.00 mg/l TDZ and ½ MS culture medium supplemented with 0.50 mg/l IBA are suggested for in vitro shoot proliferation and rooting of P. scoparia, respectively. The results presented herein could be used for in vitro selection and micropropagation of P. scoparia.

ITRAQ-based quantitative proteomics analysis of cold stress-induced mechanisms in grafted watermelon seedlings

Rootstock grafting can improve the cold tolerance of watermelon. However, the molecular mechanisms underlying this process remain unknown. Herein, we used an isobaric tag for relative and absolute quantification (iTRAQ)-based quantitative proteomics approach for the comparative analysis of protein abundances in self-grafted (SG) and pumpkin rootstock-grafted (RG) watermelon seedlings in response to cold stress. A total of 4796 distinct proteins were identified, and 752 proteins were significantly differentially accumulated in grafted watermelon seedling leaves after 48 h cold stress. Based on bioinformatics analysis, the cold tolerance of RG watermelon seedlings might be related to more energy produced through photosynthesis, carbon metabolism, and oxidative phosphorylation, compared with that of SG watermelon seedlings. RG watermelon seedlings could cope with cold stress by improving the scavenging capacity of ROS and arginine biosynthesis. Posttranscriptional regulation and protein homeostasis also play important roles for grafted watermelon seedlings to adapt to cold stress. Several protein kinases involved in signal transduction may act as positive regulators in RG watermelon seedling leaves suffering from cold stress. In addition, iTRAQ data were confirmed to be reliable by the assays of physiological indicators and relative transcript levels of eight genes. Biological significanceRootstock grafting is regarded as an effective method to enhance the cold tolerance of watermelon seedlings. To elucidate the cold tolerance mechanism of grafted watermelon, an iTRAQ-based quantitative proteomics approach combined with bioinformatics analysis was employed to identify differentially accumulated proteins in SG and RG watermelon seedlings between cold stress and control conditions. This study provided additional insight into the molecular basis of the grafted watermelon seedlings in response to cold stress.

Litchi (Litchi chinensis Sonn) propagation. New Technologies and innovations

Abstract The different propagation systems for litchis are reviewed. After examining the main morphological and developmental characteristics of the plant and the description of the structures and materials, including types of substrate required for the propagation of this species, the different methods for its propagation are discussed. Propagation by seeds is only used for breeding or research purposes or for raising rootstock for grafting. Although propagation by cuttings is done in many countries and stooling has been reported as highly successful in India, air layering is the most common commercial way of propagation for this species. Despite that the cambium activity varies from place to place around the stem with only 30% of the cambium being active at any one time grafting is of current use in China.

Using rootstock to increase watermelon fruit yield and quality at low potassium supply: A comprehensive analysis from agronomic, physiological and transcriptional perspective

Abstract Grafting is a widely used technique in watermelon production. How grafting affects watermelon fruit yield and quality at low potassium supply and the mechanism remains unclear. This study addresses the question from agronomic, physiological and transcriptional perspective. Watermelon plants [Citrullus lanatus (Thunb.) Matsum. and Nakai, cv. Zaojia 8424], either self-grafted or grafted onto the rootstock ‘Yongshi’ (Citrullus lanatus sp.), ‘Jingxinzhen No.1’ (Lagenaria siceraria Standl.), and ‘Qingyanzhen No.1’ (Cucurbita maxima × C. moschata). Plants were subjected to 6.0 mM K (normal K) and 0.1 mM K (low K). Compared with plants treated with 6.0 mM K, those supplied with 0.1 mM K produced less fruit yield as indicated by the decrease in single fruit weight of all plants; however, a smaller decrease was observed in plants grafted onto ‘Yongshi’ (10%), ‘Jingxinzhen No.1’ (15%) and ‘Qingyanzhen No.1’ (19%) than the self- grafted watermelon (38%). The K+ concentration of stem, leaf, fruit peel and flesh were obviously higher in the rootstock- grafted plants than in the self- grafted ones under 0.1 mM K. In addition, rootstock- grafted plant had significantly higher leaf zeatin riboside and chlorophyll content. Fruit quality, including contents of total soluble solid, sucrose, vitamin C, lycopene, β-carotene, were significantly decreased in the self- grafted plants under 0.1 mM K. However, 0.1 mM K treatment did not result in an obvious decrease in most of the measured fruit quality parameters in the rootstock- grafted plants. Fruit transcriptome analysis showed that there were 670, 27, 16 and 15 differential expressed genes (DGEs) responded to 0.1 mM K in the self- grafted, ‘Yongshi’, ‘Jingxinzhen No.1’ and ‘Qingyanzhen No.1’- grafted plants, respectively, indicating that rootstock grafting decrease the sensitivity of watermelon fruit to 0.1 mM K at the transcriptome level, GO and KEGG analysis showed that most of the DGEs were enriched in cellular metabolic process and metabolic pathways. Low K (0.1 mM K) significantly increased the gene expression of potassium channel (Cla020934), but decreased the gene expression of phytoene synthase (Cla009122- responsible for lycopene synthesis) in the fruit flesh of self-grafted watermelon. Taken together, the above results suggested that compared with self- grafted plants, watermelon grafted onto rootstock can enhance plant fruit yield, quality and decrease the sensitivity of fruit flesh transcriptome to low K. The mechanism of improved performance under low potassium is discussed.

Screening wild and cultivated cucurbits against root knot nematode to exploit as rootstocks for grafting in cucumber

Yield of mono-cropped cucumber (Cucumis sativus L.) is reduced by root knot nematode (Meloidogyne incognita Kofoid and White). Use of resistant rootstocks in grafting may overcome the problem. Cucurbitaceous species were screened against root knot nematode to evaluate their use as rootstocks in grafting. Inoculation was with nematodes @ 2 J2·g-1 (J2 = second stage juvenile) of soil in pot culture at the 1 to 2 true leaf stage, 45 days after inoculation, plants were uprooted and observations made to calculate Root Knot Nematode Index (RKI). Cucurbita moschata, Cucumis metuliferus, Citrullus colocynthis and Cucumis callosus were resistant having a RKI-2. Cucurbita ficifolia, Cucurbita maxima, Cucumis melo sub sp. agrestis were moderately resistant with a RKI-3. Total phenols content in roots indicates plant resistance to M. incognita. Cucumis metuliferus had the highest mean total phenols content (16.98 mg·g- 1 of root) followed by Citrullus colocynthis (16.08 mg·g-1 of root) and Cucurbita moschata (15.37mg·g-1 of root). Resistant rootstocks possessed higher peroxidase and PPO activity than susceptible ones. Cucumis metuliferus had the highest value of peroxidase and PPO activity (3.83 OD·min-1·g-1 of root and 3.67 OD·min-1·g-1 of root) followed by Citrullus colocynthis (3.26 and 3.63 OD·min-1·g-1 of root), Cucumis callosus (3.02 and 2.98 OD·min-1·g-1 of root) and Cucurbita moschata (2.93 and 2.94 OD·min-1·g-1 of root). Cucumber scions, ‘Green Long’ and ‘NS 408’ had lower peroxidase and PPO activity of 0.64 and 1.42 OD·min-1·g-1 and 0.57 and 1.31 OD·min- 1·g-1 of root, respectively. Resistant and moderately resistant cucurbitaceous species may be used for further studies possibly leading to improved yield.

Screening wild and cultivated cucurbits against root knot nematode to exploit as rootstocks for grafting in cucumber

Yield of mono-cropped cucumber (Cucumis sativus L.) is reduced by root knot nematode (Meloidogyne incognita Kofoid and White). Use of resistant rootstocks in grafting may overcome the problem. Cucurbitaceous species were screened against root knot nematode to evaluate their use as rootstocks in grafting. Inoculation was with nematodes @ 2 J2·g-1 (J2 = second stage juvenile) of soil in pot culture at the 1 to 2 true leaf stage, 45 days after inoculation, plants were uprooted and observations made to calculate Root Knot Nematode Index (RKI). Cucurbita moschata, Cucumis metuliferus, Citrullus colocynthis and Cucumis callosus were resistant having a RKI-2. Cucurbita ficifolia, Cucurbita maxima, Cucumis melo sub sp. agrestis were moderately resistant with a RKI-3. Total phenols content in roots indicates plant resistance to M. incognita. Cucumis metuliferus had the highest mean total phenols content (16.98 mg·g- 1 of root) followed by Citrullus colocynthis (16.08 mg·g-1 of root) and Cucurbita moschata (15.37mg·g-1 of root). Resistant rootstocks possessed higher peroxidase and PPO activity than susceptible ones. Cucumis metuliferus had the highest value of peroxidase and PPO activity (3.83 OD·min-1·g-1 of root and 3.67 OD·min-1·g-1 of root) followed by Citrullus colocynthis (3.26 and 3.63 OD·min-1·g-1 of root), Cucumis callosus (3.02 and 2.98 OD·min-1·g-1 of root) and Cucurbita moschata (2.93 and 2.94 OD·min-1·g-1 of root). Cucumber scions, ‘Green Long’ and ‘NS 408’ had lower peroxidase and PPO activity of 0.64 and 1.42 OD·min-1·g-1 and 0.57 and 1.31 OD·min- 1·g-1 of root, respectively. Resistant and moderately resistant cucurbitaceous species may be used for further studies possibly leading to improved yield.

Quality evaluation of Coffea canephora ‘Apoatã’ seeds for rootstock production

<p><em>Coffea canephora</em> ‘Apoatã’ seeds are used for the formation of rootstocks for grafting of <em>C. arabica</em> seedlings. The quality of seeds and the individualization of used genotypes are prevalent factors for the formation of vigorous rootstocks that will enhance the formation of quality seedlings. The aim of the present study was to characterize and evaluate the seed quality of <em>C. canephora</em> ‘Apoatã’ genotypes for potential use of rootstocks for <em>C. arabica</em> species. Were used seeds of 30 <em>C. canephora</em> ‘Apoatã’ genotypes, obtained from the experimental field of Embrapa Rondônia in Ouro Preto do Oeste, RO, Brazil. The seeds were processed and subjected to germination, first germination count and tetrazolium tests. Moisture, 100- seed mass and chemical composition analyses of seeds were also determined. The mass, physiological quality and chemical composition of <em>C. canephora</em> ‘Apoatã’ seeds vary according to the genotype. The variation of the physiological quality of <em>C. canephora</em> ‘Apoatã’ seeds is not related individually to caffeine, total sugars, ash, ether extract, crude fiber protein and chlorogenic acid. Seed batches of <em>C. canephora</em> ‘Apoatã’ from different genotypes contain seeds of different sizes, being indicated the classification before the processing stage in order to prevent mechanical damages.</p>

Comparison of Photosynthetic Physiological Characteristics and Yield of Watermelon Varieties with Different Resistance to Fusarium Wilt

With the continuous development of facilities and horticulture, the area of vegetable planting in facilities increased year by year. Watermelon (Citrullus vulgaris Schrad) as the main cultivars within the facility, the continuous cropping problem is very serious, resulting in continuous cropping obstacles become increasingly obvious, the incidence of fusarium wilt increased year by year. Grafted watermelon roots developed to improve the growth of grafted roots of the conditions, resulting in robust plant growth. At the same time, the use of different purposes of the rootstock can make watermelon in different soil conditions under normal growth, such as the use of low temperature, drought, salt tolerance, barren and other characteristics of the rootstock. Secondly, the rootstock of the strong absorption of water absorption capacity, to promote the growth of grafted watermelon plants strong, large watermelon fruit, high yields. In addition, grafted watermelon seedlings grow fast early, for early maturing cultivation and overcome the seedless watermelon early growth slow defects is extremely favorable. So the use of pumpkin as a watermelon grafting rootstock, can effectively improve the effect of watermelon resistance to Fusarium wilts. And provide the theoretical basis and scientific basis for the further study of photosynthetic characteristics, disease resistance breeding and effective control of watermelon. In this experiment, the watermelon varieties with different resistance to fusarium wilt were selected, and the anti-fusarium wilt watermelon was studied systematically. There are changes in physiological characteristics during growth and development. In conclusion, grafting promotes the growth of watermelon and physiological characteristics of the index rose. KEYWORDS: watermelon; fusarium wilt; growth period; physiological characteristics

CLONAL FORESTRY OF Araucaria angustifolia: PLANTS PRODUCED BY GRAFTING AND CUTTINGS CAN BE USED FOR WOOD PRODUCTION1

ABSTRACT Araucaria angustifolia (Brazilian Pine or Araucaria) is a potential native species to Brazilian forestry. However, a number of challenges and technical restraints still persist, making difficult its expansion as a species for forest plantations, among which the lack of cloning technologies evaluation in field conditions. So the present study aimed to evaluate the potential use of Araucaria plants produced by cuttings and grafting for wood production in comparison to those produced by seeds, by assessing field vigor and establishing a form factor for plantations with equivalent age. Plants from cuttings and seeds were planted in a 3 x 3 m spacing, being part of the last intended to be rootstocks for grafting. The experiment was conducted in a completely randomized design with three treatments and plots of a plant (one tree plot). Plants from cuttings had higher growth in diameter at breast height (7.4 ± 2.41 cm) and total height (4.2 ± 1.08 m) at 74 months after planting, followed by grafted plants and from seeds, with similar results. We conclude that cuttings and grafting are potential techniques for Araucaria plants formation for wood production, and, in particular, grafting is recommended by the easiness of in its application, besides the fact that it can be used for seed orchards formation and presents volumetric increase and form factor similar to seedlings.

Mexican native tomatoes as rootstocks to increase fruit yield

Tomato (Solanum lycopersicum L.) is one of the most economically important vegetables in the world. Mexico is considered as its center of domestication and there is a large genetic diversity. Grafting in tomato has grown for various purposes including the increase of yield. An alternative use of native tomato genotypes is as rootstocks for grafting improved tomato. The objective of this work was to evaluate native accessions of tomato as rootstocks to identify outstanding genotypes for their potential to be used as rootstocks in tomato production. An experiment was conducted for two cropping cycles (2014 and 2015) in greenhouse and hydroponic conditions, in a randomized complete block design (RCBD) with three replicates and 10 plants per experimental unit. Treatments were formed by a combination of nine native tomatoes and two commercial rootstocks with two hybrids used as scions. Twelve traits were recorded and most of the treatments were significantly different (P < 0.05) from each other for these traits. The accessions LOR-22, LOR-77, LOR-81, LOR-84, LOR-95 and LOR-100 with the hybrid ‘El Cid’, and LOR-81, LOR-84 and LOR-100 with the hybrid ‘Sun 7705’, increased significantly yield by 19% and 22%, respectively, compared to ungrafted control. Moreover, characteristics related to fruit quality were preserved with grafting. The best combination scion/rootstock (‘Cid’/100) yielded 30% higher than hybrid ‘El Cid’ without grafting and 16% higher than the commercial rootstock ‘Multifort’. This allowed identifying genotypes of Mexican native tomatoes with great potential to be used as rootstocks or as source of germplasm for rootstock development.