Rhizome Root Research Articles

Methods of adventitious rooting of rootstocks for quince trees

The aim was to evaluate techniques to enhance the adventitious rooting of ‘Adams’, ‘BA-29’, ‘EMA’, ‘EMC’ and ‘Sydo’ (Cydonia oblonga) quince trees as well as Chaenomeles sinensis quince trees with a rootstock for C. oblonga. Woody and semihardwood cuttings were removed from six quince trees, and the rooting capacity was evaluated. Seedlings of the C. sinensis rootstock were produced, and double grafting was performed using the six quince trees as intergrafting and ‘Bereckzi’ as grafts and the anatomical sections were evaluated. The seedlings were transplanted to pots. Half the length of the intergrafting was buried to stimulate adventitious rooting. Double grafting is viable. A low rooting capacity is observed for the ‘BA-29’ and C. sinensis quince tree combination, both in their cuttings and when they are the intergrafting.

Biostimulants and indolebutyric acid improve rooting of wood cuttings from different grapevine rootstocks

The rooting of rootstocks is considered a critical point in the production of high-quality grapevine planting material. To maximize the cutting rhizogenesis process, plant hormones, such as auxins, are used for the development of adventitious roots. In addition, some groups of biostimulant have as their main role the development of root system, ensuring good growth of the plant aerial part. However, research using algae extract-based biostimulants in vegetative propagation of vine rootstocks is scarce. In this sense, the objective of this work was to evaluate the use of the biostimulant based on algae extract and indolebutyric acid (IBA), in the development of the root system and vegetative growth of grapevine rootstocks. The rootstocks evaluated were ‘3309 C’, ‘101-14 Mgt’, ‘Paulsen 1103’, ‘99 R’, ‘110 R’, ‘Kober 5BB’, ‘SO4’, ‘420A Mgt’, ‘Solferino’, ‘Gravesac’, ‘IAC 572’, ‘IAC 766’, ‘IAC 313’, ‘Harmony’, ‘Freedom’, ‘Salt Creek’ and ‘VR 043- 43’. The experimental design was completely randomized with four replications, arranged in a factorial scheme, involving 17 rootstocks associated with four treatments to stimulate rooting (IBA, algae extract, IBA + algae extract and control). The use of indolebutyric acid and algae extract-based biostimulant proved to be efficient in rooting woody cuttings from different vine rootstocks. The use of IBA, algae extract-based biostimulant and IBA combined with algae extract resulted in higher rates of rooting and development than the control. The rootstocks presenting the highest rooting rates and vegetative development were ‘IAC 572’ and ‘Freedom’. ‘Gravesac’, ‘101-14 Mgt’ and ‘99 R’, showing high rates of rooting and root development, but low vegetative development. The rootstocks exhibiting the lowest rooting rates and vegetative development were ‘Salt Creek’, ‘VR 043-43’ and ‘110 R’.

Protocolo de enraizamento in vitro de porta-enxertos de Pyrus comunnis

ABSTRACT: Effective protocols for in vitro rooting for woody fruit trees are still a challenge for in vitro seedling production, especially when there is a need to insert new cultivars or rootstocks. These protocols are essential to accelerate studies in plant breeding programs and for seedling distribution. This study evaluated the use of 6-Benzylaminopurine (IBA) in in vitro rooting of Pyruscomunnis rootstocks, clones ‘OHxF87’ and Pyrodwarf. Explant exposure times (0, 24, 48, 72, and 96 hours) to 20 mg L-1 IBA were tested for in vitro rooting. The exposure to IBA resulted in rooting rates above 80%, surpassing some results reported in the literature. The 24-hour treatment provided 81,81% survival, leading to an average growth of five roots with 19 mm length, for ‘OHxF87’ rootstock. The same exposure time resulted in the highest survival rate (75%) and the highest mean root number, seven roots per plant with 10 mm length, for ‘PDW’ rootstock. Root formation did not occur in the absence of synthetic auxin. Therefore, it can be concluded that a 24-hour exposure at 20 mg L-1 IBA was sufficient to promote in vitro rooting in ‘OHxF87’ and Pyrodwarf rootstocks’.

Scion-to-Rootstock Mobile Transcription Factor CmHY5 Positively Modulates the Nitrate Uptake Capacity of Melon Scion Grafted on Squash Rootstock

It is generally recognized that the root uptake capacity of grafted plants strongly depends on the rootstocks' well-developed root system. However, we found that grafted plants showed different nitrate uptake capacities when different varieties of oriental melon scion were grafted onto the same squash rootstock, suggesting that the scion regulated the nitrate uptake capacity of the rootstock root. In this study, we estimated the nitrate uptake capacity of grafted plants with the different oriental melon varieties' seedlings grafted onto the same squash rootstocks. The results indicated a significant difference in the nitrate uptake rate and activity of two heterologous grafting plants. We also showed a significant difference in CmoNRT2.1 expression in the roots of two grafting combinations and verified the positive regulation of nitrate uptake by CmoNRT2.1 expression. In addition, the two varieties of oriental melon scion had highly significant differences in CmHY5 expression, which was transported to the rootstock and positively induced CmoHY5-1 and CmoHY5-2 expression in the rootstock roots. Meanwhile, CmHY5 could positively regulate CmoNRT2.1 expression in the rootstock roots. Furthermore, CmoHY5-1 and CmoHY5-2 also positively regulated CmoNRT2.1 expression, respectively, and CmoHY5-1 dominated the positive regulation of CmoNRT2.1, while CmHY5 could interact with CmoHY5-1 and CmoHY5-2, respectively, to jointly regulate CmoNRT2.1 expression. The oriental melon scion regulated the nitrate uptake capacity of the melon/squash grafting plant roots, and the higher expression of CmHY5 in the oriental melon scion leaves, the more substantial the nitrate uptake capacity of squash rootstock roots.

A quantitative assessment of factors affecting the rooting of grapevine rootstocks (Vitis vinifera L.)

Grapevine is a fruit species of great agronomic interest since both fresh fruit and wine are highly marketable products. Therefore, there is growing interest in this crop among researchers in the pursuit of increased yields and better cultivation conditions. Asexual propagation is the most commonly used method for propagating grapevine seedlings, with cuttings used for rootstock formation and subsequent grafting of materials to form the canopy. The rootstock is responsible for support, water, and nutrient uptake, thus determining the vigor of the plant; therefore, it is essential to understand the suitable conditions in which roots can thrive and thereby enhance plant growth. The type of cutting, type of substrate, and application of exogenous auxins are among the factors that interfere with the rooting of grapevine rootstocks, and determining and implementing the best combination of these factors could provide for more vigorous plants. Reviewing high-quality published scientific research from diverse countries is a method of identifying data, grouping information, and obtaining reliable answers. Furthermore, it can allow for the detection and grouping of the main factors affecting the rooting of grapevine cuttings, thus enabling a clearer recommendation and better understanding of the issue.

The Control Efficacy of Sodium Hypochlorite against Violet Root Rot Caused by Helicobasidium mompa in Apple.

Our study was carried out to determine the control efficacy of sodium hypochlorite (NaOCl) for violet root rot caused by Helicobasidium mompa in apple. The experiment was conducted in the farm located at Chungbuk province in South Korea from 2014 to 2016. When infected apple trees were treated at least two or three times with 31.25 and 62.5 ml/l available chlorine content in NaOCl, it greatly increased the rooting of rootstock, and restored the tree crown density by 44.4–60.5%. In addition, the number of commercial fruit setting was increased by 54.3–64.5%, and the total starch content in shoots was significantly higher than other non-treated apple trees. However, the untreated disease control and thiophanate-methyl WP treated trees showed the symptom of dieback. Therefore, our results indicate that the drenching treatment of NaOCl with 31.25–62.5 ml/l available chlorine content more than two times from late fall to early spring could effectively control the violet root rot and recover tree vigor up to 60%.

The interaction of the pathogen Fusarium proliferatum with Trichoderma asperellum characterized by transcriptome changes in apple rootstock roots

Apple replant disease (ARD) is a traditional soil-borne disease. In China, Fusarium proliferatum f. sp. malus domestica MR5, a specialized ARD-associated pathogen, caused irreversible damage to plant roots. While inoculating with endogenous antagonist Trichoderma asperellum 6S-2 can alleviate the damage caused by F. proliferatum, but the specific mechanism is still unclear. RNA-Seq was used to explore the molecular mechanism of apple rootstock roots M9T337 roots inoculated with T. asperellum followed by F. proliferatum infection, the phenotype and physiological indicators of seedlings were also assessed in this study. The results showed that F. proliferatum significantly reduced the biomass of seedlings and destroyed the root structure. After pre-inoculation with T. asperellum spore suspension, the activities of antioxidant enzymes and net photosynthetic rate (Pn) of the plants were enhanced, which maintained the health of plants. The results of gene ontology (GO) analysis indicated that most differentially expressed genes (DEGs) were involved in the signal transduction process in biological regulation, while the DEGs identified by kyoto encyclopedia of genes and genomes (KEGG) enrichment were mainly clustered in the pathways of phenylpropanoid biosynthesis and starch and sucrose metabolism. MapMan displayed changes in related transcription factors, kinases involved in regulating stress signaling and secondary metabolite synthesis after T. asperellum colonization followed by F. proliferatum. The quantification of 26 stress-related DEGs by quantitative real-time reverse transcriptase-PCR (qRT-PCR) was also confirmed. It indicated that the expression of stress-related hormone signals (ethylene/jasmonic acid) may be activated after inoculation with T. asperellum spore suspension, synthesizing phenylpropanoid secondary metabolites to resist the influence of pathogen infection.

Combined intensive management of fertilization, tillage, and organic material mulching regulate soil bacterial communities and functional capacities by altering soil potassium and pH in a Moso bamboo forest.

Intensive management is a common practice in agricultural and forestry ecosystems to improve soil quality and crop yield by influencing nutrient supply and soil microbiota; however, the linkage between soil nutrients and bacterial community and functional capacities in intensively managed economic forests has not been well studied. In this study, we investigated the soil properties such as available potassium (AK), available nitrogen (AN), available phosphorus (AP), ammonium (NH), nitrate (NO), organic matter (OM), total nitrogen (TN), total phosphorus (TP), bacterial diversity and community composition, potential functions of rhizome roots, and soil microbiota across a chronosequence of intensively managed Moso bamboo (Phyllostachys edulis) forests. Our results demonstrated that the combined intensive management (deep tillage, fertilization, and organic material mulching) in this study caused a significant increase in the concentrations of AK, AN, AP, NH, NO, OM, TN, and TP (P < 0.05). However, they led to a remarkable decrease in pH (P < 0.05). Such changes lowered the Shannon diversity of the soil and rhizome root microbiota but did not significantly affect the community composition and functional capacity. Soil bacterial community variation was predominantly mediated by soil total potassium (TK) (15.02%), followed by pH (11.29%) and AK (11.13%). We further observed that Nitrospirae accounted for approximately 50% of the variation in soil pH, NO, NH, and AK, indicating its importance in soil nutrient cycling, especially nitrogen cycling. Accordingly, we propose that the management-induced changes in soil parameters reshaped the bacterial community structure and keystone bacterial assemblage, leading to the differentiation of microbial functions.

Growth and Development Responses of the Rhizome-Root System in Pleioblastus pygmaeus to Light Intensity.

Light, as a primary source of energy, directly or indirectly influences virtually all morphological modifications occurring in both shoots and roots. A pot experiment was conducted to assess the growth patterns of one-year-old Pleioblastus pygmaeus plants’ rhizome-root systems and their responses to different light intensities from 11 March to 26 December 2016. The experiment design scheme was 3.87% (L1), 11.25% (L2), 20.25% (L3), 38.76% (L4), 60.70% (L5), and 100% full sunlight (control CK). The results indicated that along the growing period from March to December, eight of the eleven studied parameters of the rhizome-root system showed significant variability and diverse growth patterns. In addition, light intensity is a key factor for determining P. pygmaeus plants’ rhizome and root growth. Specifically, the light intensity had a significant, positive, and linear/or almost linear impact on the number of old and new rhizomes, old rhizome length, new rhizome diameter, as well as the culm root diameter. A nonlinear and positive relationship was found between light intensity and the listed three parameters, i.e., new rhizome length, new rhizome internode length, and rhizome root length. The value of the above-mentioned three parameters significantly increased when affected from 0% to 40–60% of full sunlight and then gradually increased until 100% of full sunlight. The ratio of aboveground dry weight to underground dry weight (A/U ratio) showed a single peak curve with increasing light intensity and presented the highest value under ca. 55% full sunlight. Furthermore, 40% full sunlight (equal to an average light of 2232 lux) might be the threshold for P. pygmaeus rhizome-root system growth. When the light intensity was below 40%, the generalized additive models (GAMs) predicted value of most studied parameters decreased to lower than zero. In conclusion, current study provides a solid basis for understanding the dynamic growth and development of P. pygmaeus rhizome-root system, and its responses to different light conditions, which could be used as inputs to P. pygmaeus plant cultivation.

Evaluation of physicochemical properties and shelf life of regular‐fat model sausages by wrapping with sodium alginate active film containing different levels and drying method of lotus rhizome root powder

The objective of this study was to investigate shelf-life effect of regular-fat model sausages (RFMSs) wrapped with sodium alginate films (SAFs) containing 1% dried lotus rhizome root powder (LRRP) with different drying methods. After SAFs wrapping, the pH, moisture content, and expressible moisture of RFMSs were decreased, but the crude protein and fat contents tended to increase. 1% oven-dried LRRP was added to SAFs to make the SAFO, and its wrapping decreased total bacterial counts in RFMSs on day 21 and day 35. The microbial counts of Enterobacteriaceae of RFMSs wrapped with SAFO were lower than those of control RFMSs from day of 28 to day 35. RFMSs wrapped with SAFs containing LRRP had higher chewiness and cohesiveness than those of control RFMSs (p < 0.05). Therefore, SAFO wrapping can retard microbial growth and prolong the shelf-life of RFMSs since SAFs prevented microbial growth and LRRP had an antimicrobial activity.

Evaluation of antioxidant activities of lotus rhizome root powder prepared by different drying conditions and its application to raw and cooked pork patties

This study was to investigate the antioxidant activities of lotus rhizome root powders (LRRPs) prepared by different drying conditions and with different particle sizes, and the effect of LRRP on the physicochemical properties and shelf-life of raw and cooked patties. The total phenolic contents (TPCs) and total flavonoid contents (TFCs) of oven-dried LRRP (ODLRRP) at 100°C were higher than those of freeze-dried LRRPs (FDLRRPs) and ODLRRP at 60 or 80°C. TPCs, TFCs and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) values of LRRPs increased with increasing temperatures and decreasing particle sizes. The 2-thiobarbituric acid reactive substance (TBARS) values and volatile basic nitrogen (VBN) contents of raw patties with LRRPs added were decreased. Lightness, microbial counts of total bacteria and Enterobacteriaceae in raw patties, and the total bacterial counts of cooked patties with 1% ODLRRP at 100°C added were decreased. The redness of raw patties with FDLRRP added was increased, whereas the yellowness was increased by 100°C ODLRRPs addition. The color, TBARS, and VBN values of cooked patties with LRRPs added were decreased. The cooking process increased the TBARS and VBN but reduced microbial counts. Therefore, 1% 100°C ODLRRPs (< 150 μm) was effective in extending the shelf-life of raw and cooked patties during storage.

Effect of sodium alginate active film incorporating different lotus rhizome root powders on the physicochemical properties and shelf-life of low-fat model sausages

Low-fat model sausages (LFMSs) were wrapped in sodium alginate films (SAF) with different lotus rhizome root powders (LRRP) and their effects on the physicochemical properties and shelf-life effects of LFMSs were investigated. Oven-dried LRRP (OD LRRP) at 100 °C had the highest antioxidant activity among all LRRP. The pH values of SAF with 1% freeze-dried LRRP added were increased but decreased with 1% OD LRRP added. The lightness and thickness of the SAF decreased, but redness, yellowness, total color difference, and swelling ratio increased by the addition of LRRP. The antioxidant activity of SAF with 1% OD LRRP (SAFO) added were the best among all treatments. The 2-thiobarbituric acid reactive substances, total bacterial count, and Enterobacteriaceae of LFMSs wrapped in SAFO were decreased. The texture profile of LFMSs wrapped in SAF increased but the expressible moisture decreased. Therefore, LFMSs wrapped in SAFO might retard microbial growth and lipid oxidation during storage.

The Effect of Rootstock Activity for Growth and Root System Soaking in Trichoderma atroviride on the Graft Success and Continued Growth of Beech (Fagus sylvatica L.) Plants

Two independent experiments were conducted on the effect of various factors, such as cultivars, growth activity of the rootstock and its treatment, with Trichoderma atroviride on graft success and growth of annual beech plants. The first experiment concerned the effect of propagation of five beech cultivars on rootstocks that are active (with growth activity), grown before the treatment in multi-cell plant trays (plastic seedling trays) or bare-root in the dormancy period. The highest success rate of the treatment was observed for dormant (without growth activity) and bare-root rootstocks. However, the best plant growth parameters during the first year of cultivation were observed when grafting active rootstocks obtained from multi-cell plant trays, while the worst results were observed for dormant, bare-root rootstocks. The individual cultivars varied significantly in terms of graft success and continued plant growth. The second experiment concerned the effect of rootstock growth activity and soaking of the rootstock root system in Trichoderma atroviride on graft success, growth parameters, and the intensity of some physiological processes in beech plants. The simultaneous use of both above-mentioned treatments resulted in the most intensive growth and accelerated physiological processes of the plants tested. Inoculation of rootstocks with Trichoderma atroviride did not affect the graft success. On the other hand, the growth activity of rootstocks at the time of grafting increased the success rate of the treatment. The treatments similarly differentiated the results obtained for two beech cultivars tested.

A method for simultaneously monitoring phloem and xylem reconnections in grafted watermelon seedlings

Grafting is an effective way to increase watermelon's tolerances to biotic and abiotic stresses. However, the survival of grafted seedlings largely depends on successful graft formation. Therefore, understanding the graft formation process, particularly vascular reconnection, is of critical importance. This study found that lignin in watermelon stem showed strong auto-fluorescence under blue-light excitation. Consequently, blue-light excited fluorescent tracers (FTs) such as 5(6)-carboxy fluorescein diacetate (CFDA) were unsuitable for assaying vascular connectivity in watermelon. In contrast, UV-light excited esculin and red-light excited acid fuchsin proved to be efficient FTs for monitoring phloem and xylem connectivity, respectively, in self-grafted watermelon. Furthermore, combining esculin application to the scion cotyledon and acid fuchsin to the rootstock root enabled simultaneous monitoring of both phloem and xylem connectivity in individual self-grafted watermelon seedlings. Based on this assay, we found that phloem and xylem reconnections occurred simutaneously in self-grafted watermelon. Moreover, low temperature and removal of the rootstock cotyledons both delayed vascular reconnection in the self-grafted watermelon. In conclusion, this new method provided a convenient, accurate and rapid way to analyze vascular connectivity in watermelon.

Effects of lotus rhizome root powder made by different levels and drying methods on the physicochemical properties and antioxidant activity of regular‐fat model sausages

SummaryThe effects on physicochemical properties and shelf‐life of regular‐fat model sausages (RFMSs) added with oven‐dried or freeze‐dried lotus rhizome root powder (LRRP, ≤150 µm) at two different concentrations (0.5% or 1%) were investigated in this study. RFMSs added with LRRP showed decreased lightness (L*), reduced microbial counts, and thiobarbituric acid‐reactive substances (TBARS), but increased redness (a*), yellowness (b*), hardness, and cohesiveness. The changes in L*, a*, and b* of RFMSs treated with 1% oven‐dried LRRP were the largest. Furthermore, addition of 1% oven‐dried LRRP to the RFMSs minimised the TBARS value and the microbial count. RFMSs treated with LRRP had a denser and more compact microstructure than RFMSs without LRRP based on low‐vacuum scanning electron microscopy analysis. Therefore, LRRP improved the shelf‐life of RFMSs, especially 1% oven‐dried LRRP inhibited the maximum lipid oxidation and microbial growth.

Double-root-grafting enhances irrigation water efficiency and reduces the adverse effects of saline water on tomato yields under alternate partial root-zone irrigation

Since most world regions face freshwater (FW) shortages, water-saving irrigation and irrigation with saline water (SW) are currently two inevitable agricultural practices for crop production. However, these two practices generally have adverse effects on crop yields. In this study, we investigated the effects of double-root-grafting (DRG) on plant growth, crop yields, tomato quality and root-zone properties under alternate partial root-zone irrigation (APRI) with FW or SW. Self-rooting (SR), DRG, conventional irrigation (CI), APRI, FW and SW were considered in the experimental design to create treatments that included (i) SR-CI-FW, (ii) SR-APRI-FW, (iii) DRG-APRI-FW, (iv) SR-APRI-SW and (v) DRG-APRI-SW. The DRG used here is a ‘tongue approach grafting’ method in which grafted plants retain both rootstock (eggplant) root and scion (tomato) root in order to maximize the effectiveness of grafting under abiotic stress. The tested salinity level was 3.51 mS cm−1 which had exceeded the threshold salinity of tomato (2.50 mS cm−1). In general, APRI application increased water productivity by 22.2–35.6%, but decreased fruit yields by 9.1–18.8% in SR plants (SR-APRI-FW vs. SR-CI-FW). However, under APRI conditions, DRG plants showed higher rate of plant growth and less salinity damage as compared to SR plants. Application of DRG significantly (P < 0.05) increased tomato fruit yields by 7.9–17.2% under standard conditions (DRG-APRI-FW vs. SR-APRI-FW) and by 14.2–27.4% under salinity conditions (DRG-APRI-SW vs. SR-APRI-SW). Taken together, double-root-grafting enhanced irrigation water efficiency and reduced the adverse effects of saline water on tomato yields under alternate partial root-zone irrigation.

Carbonized Apple Branches Decrease the Accumulation and Damage of Cadmium on Apple Rootstock by Reducing DTPA-Cd in Soil

To explore the effects of carbonized apple branches on cadmium(Cd) accumulation and its damage to apple rootstock, the rootstocks of apple(Malus hupehensis Rehd.) in pots containing soil together with 0.5% and 1%(ω) carbonized apple branches were irrigated by a nutrient solution containing CdSO4. The content of DTPA-Cd(cadmium extracted by diethylenetriamine pentaacetic acid) in the potting soil, and the accumulation of Cd in the roots, stems, and leaves of apple rootstocks, were subsequently monitored. The activities of antioxidant enzymes in roots and leaves, root cell death, and the net photosynthesis rate were further analyzed. The results showed that the concentration of DTPA-Cd in the potting soil with carbonized apple branches was significantly lower than that without carbonized apple branches(Cd-only). Compared with the Cd-only treatment, the concentration of DTPA-Cd in the potting soil decreased by 17.50% and 25.55% in the treatment with 0.5% and 1%(ω) carbonized apple branches for 12 days. The Cd accumulation in roots, stems, and leaves; the accumulations of superoxide anions(·O2-), hydrogen peroxide(H2O2), and malondialdehyde(MDA) in roots and leaves; and the amount of cell death in the roots of apple rootstock treated by carbonized apple branches were significantly lower compared to the Cd-only treatment. However, the activities of superoxide dismutase(SOD), peroxidase(POD), and catalase(CAT) in the roots and leaves, and the net photosynthesis rate of apple rootstock treated by carbonized apple branches, were significantly higher than under the Cd-only treatment. Compared with the Cd-only treatment, Cd accumulation in roots decreased by 29.49% and 37.18% in the treatment with 0.5% and 1%(ω) carbonized apple branches for 12 days, and the amount of cell death decreased by 22.73% and 29.09%, respectively. Our results show that carbonized apple branches reduce the uptake and accumulation of Cd in apple rootstock by reducing the content of DTPA-Cd in the soil, thereby alleviating the damaging effect of Cd on cells and photosynthesis. Moreover, the use of 1%(ω) carbonized apple branches was more effective than 0.5%(ω).

Transcriptomic analysis of endoplasmic reticulum stress in roots of grapevine rootstock

Transcriptomic analysis of endoplasmic reticulum stress in roots of grapevine rootstock

Green light promotes healing and root regeneration in double-root-cutting grafted tomato seedlings

Double-root-cutting (DRC) grafting is a new grafting method that makes it possible to ship grafted seedlings without using plug trays, through cutting off the roots of both scion and rootstock. However, graft healing and root regeneration are the two important factors determining the survival of the DRC grafted plants. Recent studies have shown that green light plays a crucial role in plant growth and development. We hypothesized that green light could stimulate the graft healing and root regeneration of the rootstock in DRC grafted seedlings. To test this hypothesis, we used tomato seedlings (Solanum lycopersicum cv. Beaded Curtain grafted on cv. Rootstock No. 1) exposed to white LED lamp (W) as a control (CK). In the treatment group, green light (10, 20 and 30%) was added to the red and blue spectrum without changing the intensity of red and blue fractions. The effects of different light qualities on graft union formation, survival rate, rooting of the rootstock hypocotyls, activities of antioxidant enzymes, chlorophyll content and grafted seedling quality of grafted tomato seedlings were then studied. Compared with DRC grafted seedlings exposed to the same light intensity, addition of 30% green light to red and blue lights increased the activities of antioxidant enzymes, chlorophyll content, plant height and index of seedling strength of grafted seedlings, showed a more positive effect on the development and performance of grafted seedlings, and promoted graft union, rootstock rooting and grafted seedling growth. Increasing the proportion of green light brought about better graft union and rootstock rooting. Our results showed that green light may reduce the degree of stomatal opening and transpiration rate during the early stages of grafting. Green light increased the activity of antioxidant enzymes, which was enhanced tissue lignification. Photosynthesis was driven by green light, which improved the development of aboveground parts, enhanced the transport of auxin from leaves to rooting zone, and promoted hypocotyl rooting of DRC grafted tomato seedlings.

Characteristics of boron distribution in the ‘Newhall’ navel orange plant with two root systems

Grafting is a technique that provides a substantial way to enhance nutrient utilization thereby improves plant growth and yield quality. Although it is commonly practised in horticultural crops, the impact of scion-rootstock interaction on nutrient distribution is still unclear. Here, ‘Newhall’ navel orange plants grafted on Trifoliate orange (T) as the original rootstock were inarched with trifoliate orange (N/Tt combination) or carrizo citrange (N/Tc combination) rootstock seedlings. The experimental plants were treated with isotope 10B solution for 7 weeks to investigate the effect of different inarched rootstocks on B distribution and translocation by using a two-root system. From this study, the original rootstock played a more dominant role in B distribution to scion tissues than the inarching rootstock either in N/Tt or N/Tc combination. From inarched combinations, the carrizo citrange in the N/Tc combination had a higher ability to distribute B to new leaves, new twigs and old twigs than trifoliate orange in the N/Tt combination. However, the original rootstock of N/Tt distributed more B to scion tissues than N/Tc and the B concentration in old leaves and new leaves of N/Tt plants was significantly higher than that of N/Tc plants. These results suggest that scion B status is influenced by the B distribution of two inarching rootstocks in an inarching plant, as well as the affinity between the inarching rootstock and grafted plant. In addition, by either adding 10B to the inarching rootstock or original rootstock, we could detect 10B in the other rootstock root in both N/Tt and N/Tc combinations. The results further suggest that B can translocate from rootstock to leaves and then, re-translocate from scion to rootstock through the cycling of B transportation.