Scion Varieties Research Articles

In vivo tetraploid induction of mono-embryonic citrus genotypes by colchicine treatment

Polyploid holds great significance in citrus breeding, to produce dwarf tetraploid rootstocks with wide adaptability and triploid scion varieties bearing seedless fruits. In citrus, tetraploids have been generated through somatic hybridization and autonomous chromosome doubling of nucellar embryos. However, most tetraploids were recovered from poly-embryonic (apomictic) citrus, while tetraploids of mono-embryonic (non-apomictic) citrus were seldomly reported. Herein, we developed an in vivo tetraploid induction method by colchicine treatment, which is especially high-efficient in mono-embryonic citrus. The epicotyl of citrus seedling was decapitated and incubated in dark for different time durations (0–15 d) to induce callus formation on the epicotyl wound. The callus on wound was then immersed in different concentrations (0.0125 %-0.100 %) of colchicine for 2 h, enabling regeneration of tetraploid shoots. We achieved high tetraploid induction rate (20.69 %) but low mixoploid induction rate (1.72 %), when 0.025 % colchicine was applied on wound cultured in dark for 9 d By using this method, 147 tetraploids were recovered from mono-embryonic mandarin, tangerine, sweet orange, pummelo and citron. Our method exhibited high tetraploid induction efficiency (14.28 %-20.69 %), low rate of mixoploid (1.72 %-5.30 %), short recovery period (45 d), and no need of tissue culture. The majority (75 %-100 %) of the recovered tetraploids maintained stable ploidy during subsequent growth, and the mono-embryonic nature of the tetraploids was identified by InDel marker analysis. The mono-embryonic tetraploids obtained herein enriched polyploid germplasm pool for citrus breeding.

The rootstock genotype shapes the diversity of pecan (Carya illinoinensis) rhizosphere microbial community.

Pecans (Carya illinoinensis), one of the most valuable native North American nut crops, are commonly propagated through grafting to preserve the desired characteristics from parent trees. Since successful cultivation of pecan trees relies on the interplay among scion varieties, rootstocks, and soil conditions, this study investigated the microbial change to communities in the soils and roots of southern (87MX5-1.7) and northern (Peruque) rootstocks in a rootstock test orchard. Both grafted with the 'Pawnee' scion cultivar. Bacterial 16S ribosomal RNA and fungal ITS were amplified from both roots and rhizosphere soils of the two 10-year-grafted trees, then sequenced and annotated into trophic and nutrient-related groups to characterize the rhizosphere microbiota. The Peruque roots had a higher relative abundance of saprotroph fungi, while 87MX5-1.7 exhibited higher levels of symbiotroph fungi and nitrogen fixation-related bacteria. Among them, the presence of symbiotroph fungi, particularly ectomycorrhizal fungi, notably differed between these two rootstocks, with a significantly higher presence observed in the root of 87MX5-1.7 compared to Peruque. This variation likely leads to divergent pathways of nutrient translocation: Peruque was in favor of multiple fungi (Russula and Inocybe) to gain nutrition, while 87MX5-1.7 preferred a specific domain of fungi (Tuber) and nitrogen fixation-related bacteria (Bradyrhizobia) to form beneficial symbiosis. Moreover, the presence of pathogens suggested a potential risk of Fusarium patch and snow molds in 87MX5-1.7, while canker and black foot disease pose threats in Peruque. The findings of this study suggest that rootstocks from different origins shape rhizosphere microbes differently, potentially affecting nutrient uptake and nut yield. Exploring rootstock-microbe combinations could provide insights into optimizing scion growth and ultimately increasing nut yield. By understanding how different rootstock-microbe interactions influence pecan tree development, growers can strategically select combinations that promote beneficial symbiotic relationships, enhancing nutrient uptake, disease resistance, and overall tree vigor.

Comparison of pepper accessions acting as rootstocks: A case with low P inputs

Fertilization is essential for maintaining production in agriculture. Yet, in too high quantity it causes high impact in environment and in farmers economy. This is especially true in the case of phosphorus (P) fertilization. Finding genotypes adapted to low P conditions may help to reduce the problem. P efficiency depends to some extend on the ability of the roots to acquire this mineral, therefore using efficient rootstocks would provide a higher acquisition of P, maintaining the good characteristics of the scion varieties. In this study, twenty diverse pepper accessions (Capsicum annuum L.) have been evaluated as possible rootstocks to increase P acquisition and yield in pepper under no P fertilization. Plant production, biomass, P content and physiological phosphorous use efficiency were evaluated for ‘Lobo’ variety grafted onto different rootstocks. In addition, root traits, measured manually (shovelomics) and semi-automatically (Winrhizo) were studied. The results showed a great diversity in the root traits for the studied accessions. These root traits changed significantly when the accessions act as rootstock, indicating great rootstock/scion interactions. In general, all the rootstocks adapted their root size and shape to that displayed by ‘Lobo’ root system. Some accessions seemed to have some incompatibility whereas some others enhanced the scion performance. It was possible to identify some genotypes suitable to act as rootstocks for pepper with good performance under low P conditions. Root length, root weight, branching, and root angle were identified as key root traits for plant growth and P acquisition under low P conditions.

Rootstocks for the Mediterranean citrus industry: current choices and new releases

Modern citriculture relies on the use of rootstocks to guarantee adaptability to environmental and biotic constraints and to speed up the establishment of a potentially unlimited number of homogeneous plants of a specific clone, which in turn ensures uniformity in the production of high-quality fruit. In this contribution, the status of rootstock availability for the Mediterranean citrus industry is described along with its evolution during the last decades. The major turning points in rootstock choice were caused by the spread of new diseases, such as Citrus Tristeza Virus (CTV), that hastened the use of resistant or tolerant rootstocks. In Italy, the growers decisions on rootstock replacement were facilitated by information from rootstock trials performed for more than 70 years in several areas of southern Italy, as well as information from other countries. However, there is still the need to find alternatives to sour orange (which was the most commonly used rootstock before the CTV outbreak), especially for cultivation under suboptimal growing conditions. Nowadays, the process of replacing standard rootstocks with new ones with better performance should be assisted by a long-term evaluation strategy, since negative characteristics can become evident after many years of evaluation in combination with specific scion varieties. Ongoing rootstock breeding programs in different parts of the world and in Italy are critically described.

STANDARDIZATION OF GRAFTING HEIGHT FOR GROWTH AND DEVELOPMENT OF MANGO (Mangifera indica L.) NURSERY PLANTS

Grafting height has a significant impact on plant growth and the development of many fruits including mango. The present study was planned to optimize the height of mango rootstock for grafting at the nursery level. Three different varieties of scion (Sindhri, Sufaid Chaunsa, Chenab Gold) were grafted at three different heights (8inch, 12inch and 16inch) using wedge/cleft grafting technique on desi mango nursery seedlings. Results showed that grafting height and scion variety have a significant impact on the growth and development of mango nursery plants. Different parameters were examined and results showed that Sindhri scion grafted at 16 inches’ height significantly improved, number of flushes (2.62), number of leaves (14.55), stem girth (14.25mm), plant height (56.16cm), scion length (18.62cm), superoxide dismutase (3.70 U mg-1 protein), peroxidase (0.96 U mg-1 protein), chlorophyll b contents (6.6 g/kg). However, the scion of Chenab Gold grafted at 12 inches, performed best for grafting survival percentage (97.5 %). So it was concluded that Chenab Gold Scion performed best at 16 inches grafting height for plant growth in all aspects as compared to other scion varieties and grafting height.

Water competition in the soil by rootstocks is used to assess drought tolerance in citrus

Brazil is a country focused on agribusiness and is the world's largest producer of orange juice. However, citrus production in certain regions of the world is affected by irregular rainfall, which imposes drought stress conditions and causes behavioral changes in plant survival, growth, and productivity. In this context, the objective of this work was to assess a methodology for the selection of citrus rootstocks tolerant to drought when exposed to water deficit regimes. This work was conceived with prior knowledge of the responses to drought tolerance of three rootstocks: Rangpur Lime (RL), Sunki Tropical (ST) and Sunki Maravilha (SM). The study was carried out with Valencia Orange (VO) scion varieties grafted on these three rootstocks. Two plants were conditioned per pot, forcing competition for available water in the soil, and all combinations were exposed to three different water regimes (irrigated, water deficit, and rehydrated). The hydric and physiological relationships were then evaluated. The results showed that in addition to the availability of water, the association between genotypes in the same pot caused different physiological responses. In view of the contrasting strategies of survival/tolerance adopted by these genotypes in response to water deficit, the combination with RL allowed a higher tolerance, showing less water extraction, lower leaf water potential, and relative water content, as well as an increase in the photosynthetic parameters when combined mainly with SM. The methodology used is a promising and more effective tool for analyses of citrus plants under drought stress conditions.

Effects of Rootstock and Location on Open Field ‘BHN 589’ and ‘Nebraska Wedding’ Grafted Tomato Yield

Grafted tomato (Solanum lycopersicum) production is popular, particularly in high tunnels, because grafted plants can mitigate soilborne disease incidence in highly infested soils and increase water and nutrient use efficiency and crop yield and quality. However, these potential benefits are not as well documented in open field production systems with less disease pressure. The objective of this study was to quantify the effect of tomato grafting on fruit yield, number, and size across 2 years (2018 and 2019) and three diverse open-field production environments in Nebraska (Lincoln, North Platte, and Dwight). At each location, a scion from one of two determinant fresh market tomatoes, ‘Nebraska Wedding’ (heirloom) or ‘BHN 589’ (commercial hybrid), were grafted onto one of two rootstocks, ‘Estamino’ and ‘Maxifort,’ and the nongrafted scion cultivars were controls. In year 2, a fertilizer treatment was introduced (0 and 50 kg·ha−1 N). Ripe tomatoes were harvested weekly, sorted as marketable or cull, counted, and weighed fresh. No marketable or total yield benefits of grafting were observed in 2018 for any scion by rootstock combination across locations. Marketable yield of grafted plants was reduced by 32% in Lincoln. However, grafted ‘Nebraska Wedding’ plants (regardless of rootstock) in North Platte (with coarse-textured, lower organic matter soil) increased fruit number (but not yield) by 50% to 63%. In 2019, grafting ‘BHN 589’ to ‘Maxifort’ increased total tomato yield by 24% across all locations. The heirloom variety Nebraska Wedding did not benefit from grafting in 2019. ‘Estamino’ rootstock did not increase tomato yield, number, or size for either scion variety in either year. Nitrogen fertilizer increased yield as expected in 2019, but grafted plants did not perform better than nongrafted under reduced nitrogen fertility. Results from this study suggest that grafting is not consistently beneficial to ‘BHN 589’ and ‘Nebraska Wedding’ in open field production systems in Nebraska, particularly if there are no known soilborne disease issues.

Optimizing Tomato Grafts for Improved Growth, Yield and Fruit Quality

Low tomato production and yield in the country can be attributed to various biotic and abiotic stresses. To mitigate the impact of these challenges, vegetable grafting is gaining popularity worldwide. Furthermore, tomato growers are adopting hybrid varieties, but the majority of them face challenges affording the cost of hybrid seeds. This study was conducted in 2018 to investigate successful tomato grafting techniques aimed at enhancing growth, yield, and fruit quality. This study examined three distinct rootstocks (AS-2565, Bush beefsteak, and Roma vf), three high-yielding scion varieties (Super tomato, Rio-grande, and T-1359), and employed two grafting methods (splice and cleft). Non-grafted plants were maintained as check plants. The grafting methods showed non-significant differences in all studied parameters except grafting success, whereas the scion-rootstock combinations exhibited highly significant differences. The highest grafting success, number of fruits per plant, fruit length, fruit diameter, fruit weight, and yield per plant were observed in the T-1359 scion grafted onto the Bush beefsteak (BBS) rootstock. Regarding quality characteristics, higher levels of total soluble solids (TSS) and pH were observed in non-grafted Super tomato plants. In terms of vitamin C, titratable acidity (TA), and lycopene content, the T-1359 scion performed better across various rootstocks. In conclusion, T-1359 grafted onto the BBS rootstock proved to be a superior scion-rootstock combination in terms of growth, yield, and quality.

Stionic and Environmental Influence on the Success and Survivability of Guava Grafts (Psidium guajava L.)

Abstract: An experiment was conducted to “study the success and survivability of grafts in different scions of guava (Psidium guajava L.) by softwood grafting under different environmental conditions by using different aged rootstocks. The results revealed that, highest graft success (81.33 %) and survivability (62.66 %) was found in the shade net condition at 90 days after softwood grafting. Among the different scions, the highest graft success (84.44 %) and survivability (64.44 %) was registered in Sardar scion variety. However, interaction effect showed that, highest graft success (96.66 %) and survivability (76.66 %) was noticed in Sardar variety of scion under shadenet condition followed by polyhouse condition by using seven months old rootstock.

The Effects of Rootstock-Scion Relationships on Yield and Quality in Grapevine cv. Ekşi Kara (Vitis vinifera L.)

Vineyards are usually established by grafting onto vine rootstocks. Vine rootstocks affect the grafted varieties directly or by environmental factors and by changing the physiology of rootstock and scion varieties. There may be great differences in mineral nutrition of grape rootstocks and grape varieties in grafted and nongrafted combinations. The choice of grape variety and vine rootstock for vineyard ecology is vital for the sustainability of viticulture, as they affect the mineral nutrient balances, biotic and abiotic stress tolerances, yield and product quality of grape rootstocks and grafted varieties, and these change with edaphic factors. This study was carried out in ~20 years old vineyards established with vines on their own roots of Ekşi Kara grape variety (Pollinator is Gök Üzüm), which is most used in production in Konya province, and seedlings grafted onto 41B, 110R and Rupestris du Lot rootstocks. The effects of rootstock and scion nutrition were searched. Yield per vine, cluster weight, cluster number, cluster length and cluster width data showed the highest values from vines on their own roots, while the order of grafted combinations changed according to the trait measured. While the differences between °Brix and total acidity (TA) values of berry were significant (p<0.05), differences in pH and must yield were insignificant in grafted and nongrafted combinations. Nutrient contents of leaf and root samples were different compared to grafted and nongrafted combinations. Since our study area is infested with phylloxera (Daktulosphaira vitifoliae Fitch) and rootstock use is obligatory, the order of preference for grapevine rootstocks was 41 B, Rupestris du Lot and 110 R, considering yield and quality characteristics.

The transcriptionally active bacterial communities of grapevine rhizosphere in dependence on rootstock and scion variety

The rhizosphere is where crucial processes for the productivity of viticultural systems occur. The composition of the bacterial communities associated with the rhizosphere of grapevines is known to depend on plant genotype. However, the genotype of grafted grapevines differs between scion and rootstock; the role of each genotype is unclear. To untangle the effect of scion and rootstock, the rRNA (V4–V5 region of 16S rRNA) extracted from the rhizosphere of the grape varieties Riesling and Mueller-Thurgau ungrafted vs grafted on different rootstocks was sequenced. The bioinformatic analysis with tools designed to be robust for compositional data showed that the investigated rootstocks or scions or combinations, respectively, recruited bacterial communities with distinguishable traits. Statistical differences were revealed between ungrafted Riesling vs Mueller-Thurgau, between grafted Riesling vs ungrafted Riesling, and between ungrafted Mueller-Thurgau vs grafted Mueller-Thurgau. Thus, confirming the role of scion and rootstock genotype as a driver of the structure and composition of bacterial communities in the rhizosphere of grapevines.

COMPARATIVE STUDY OF ROOTSTOCKS AND THEIR EFFECTS ON STIONIC ESTABLISHMENT OF THE MANGO SEEDLINGS

To explore the quality rootstock which impart better stionic establishment of the mango seedlings, we studied the comparative effect of scion and rootstock using three mango scion varieties (Sindhri, Chaunsa and Neelum) grafted on three rootstocks i.e. Ratam, Pado and Sindhri. Parameters including seed germination (%), seedling height (cm), leaves seedling rootstock-1, seedling vigor index (SVI), fresh biomass of shoot and roots (g), dry biomass of shoot and roots (g), chlorophyll content (rg), rootstock diameter (mm), scion diameter (mm), stionic ratio, leaves graft-1 and sturdiness quotient were studied. Results showed the best seed germination (88.33%), seedling vigor index (5158.74), and sturdiness quotient (3.89) in Pado rootstock. However maximum fresh biomass of shoot (20.67 g), fresh biomass of roots (16.2 g), dry biomass of shoot (12.65 g), dry biomass of roots (8.33 g) and scion diameter of the rootstocks were observed in Sindhri rootstocks. Regarding grafting data, the best stionic ratio (0.93) was observed from the scion and rootstock combination of Neelum and Pado rootstock. It was concluded that Pado rootstock performed better in terms of seedling rootstock and for successful stionic establishment of the mango seedlings

The role of rootstocks for grape growing adaptation to climate change. Meta-analysis of the research conducted in Spanish viticulture

Rootstock election is one of the key decisions when designing a vineyard. Although the research performed to determine the effect they induce in the behaviour of scion varieties is not scarce, it is not easy to have a global idea, as results are usually published scattered. In this work, we re-examine previous research conducted in Spain on rootstock implications on vine agronomic performance through the performance of a meta-analysis (MA). As a result, we were able to integrate the information reported in 20 articles that included rootstock experimentation conducted with 36 different varieties and 47 different rootstocks, totalling 764 individual records. However, when the information was filtered before the meta-analysis, this number decreased to 312 records, for which rootstock Response Ratios (RR) were calculated. The characteristics conferred by the rootstock were more closely related to the rootstock itself, rather than to the characteristics of the Vitis sp. crossing used to create the rootstock. Several rootstocks were identified as more suitable for adapting to future climate change conditions, as far as they were able to moderate sugar accumulation and pH (161-49 C, 41-B MGt and 420A MGt). Meanwhile, 140 Ru and 5-BB were observed to provide high pH and sugar contents despite their high yield. In conclusion, despite being based on data from a single country, the meta-analysis was shown to be a useful tool for enhancing the value of previous research on rootstocks. Combining articles from both peer-reviewed and technical journals helped in the assessment of the implications of different rootstocks, although further steps should be taken to facilitate data integration (harmonisation of measurement and reporting procedures, open data repositories, etc).

Rootstock-mediated carbohydrate metabolism, nutrient contents, and physiological modifications in regular and alternate mango (Mangifera indica L.) scion varieties.

Most of the popular scion varieties of mango possess alternate/irregular bearing. There are many external and internal factors assigned, among them carbohydrate reserves, and nutrient content plays important roles in the floral induction process in many crop species. In addition to that rootstock can alter the carbohydrate reserve and nutrient acquisition of scion varieties in fruit crops. The present investigation was carried out to understand the effect of rootstocks on the physiochemical traits of leaf, and bud and nutrient content in regular and alternate bearing varieties of mango. The rootstock "Kurukkan" promoted starch content in leaves of both alternate bearing varieties 'Dashehari' (5.62 mg/g) and regular 'Amrapali' (5.49 mg/g) and encouraged higher protein content (6.71 mg/g) and C/N ratio (37.94) in buds of alternate bearing 'Dashehari'. While Olour rootstock upregulated the reducing sugar in leaves of 'Amrapali' (43.56 mg/g) and promoted K (1.34%) and B (78.58 ppm) content in reproductive buds of 'Dashehari'. Stomatal density in 'Dashehari' scion variety was found higher on Olour rootstock (700.40/mm 2), while the rootstock fails to modify stomatal density in the scion variety regular bearer 'Amrapali'. Further, a total of 30 carbohydrate metabolism-specific primers were designed and validated in 15 scion/rootstock combinations. A total of 33 alleles were amplified among carbohydrate metabolism-specific markers, which varied from 2 to 3 alleles with a mean of 2.53 per locus. Maximum and minimum PIC value was found for NMSPS10, and NMTPS9 primers (0.58). Cluster analysis revealed that scion grafted on Kurukkan rootstock clustered together except 'Pusa Arunima' on Olour rootstock. Our analysis revealed that Fe is the key component that is commonly expressed in both leaf and bud. Although Stomatal density (SD) and Intercellular CO2 Concentration (Ci) are more specific to leaf and Fe, B, and total sugar (TS) are abundant in buds. Based on the results it can be inferred that the physiochemical and nutrient responses of mango scion varieties are manipulated by the rootstock, hence, the scion-rootstock combination can be an important consideration in mango for selecting suitable rootstock for alternate/irregular bearer varieties.

The Effect of Interstock on The Development of Huanglongbing Disease and Vegetative Growth of Three Commercial Citrus Varieties in Indonesia

Huanglongbing (HLB) disease, causes a 60-95% decline in Indonesia citrus production in almost all production centers. The use of suitable citrus interstocks can increase fruit production and quality, improve compatibility, and can also increase tolerance to HLB with tolerant interstocks. Potential interstock, providing an alternative for citrus farmers to be able to save their plants from the destruction of HLB. The purpose of this study was to determine the effect of several interstocks in inhibiting the development of HLB disease and the growth of citrus plants. Eight interstock combination treatments (JC, JC+Rough lemon, JC+Carrizo citrange, JC+citrumelo, JC+Poncirus trifoliata, JC+Volkamer lemon, JC+Troyer citrange and JC+ Kanci kumquat) on 3 commercial citrus varieties (C. reticulata var. Batu 55, C. nobilis var. Pontianak and C. aurantifolia var. Nimas Agrihorti). The combination of interstock affects plant tolerance to HLB. In the three upper limit varieties tested, the mildest symptoms of HLB and the healthiest was found in the combination of interstock JC+P.trifoliata, and Candidatus Liberibacter asiaticus were detected after inoculation using conventional PCR amplification in the second test. Based on the PCR index and the severity of the symptoms, the combination of interstock JC+P. trifoliata was classified as mild severity and the healthiest against CLas infection in the 3 scion varieties tested (C. reticulata var. Batu 55, C. nobilis var. Pontianak and C. aurantifolia var. Nimas Agrihorti). Vegetative growth was found to be varied, and almost all of them could grow well except shoot growth which was stagnant at 5-6 months after inoculation.

Physiological and Transcriptomic Evaluation of Drought Effect on Own-Rooted and Grafted Grapevine Rootstock (1103P and 101-14MGt)

Grapevines worldwide are grafted onto Vitis spp. rootstocks in order to improve their tolerance to biotic and abiotic stresses. Thus, the response of vines to drought is the result of the interaction between the scion variety and the rootstock genotype. In this work, the responses of genotypes to drought were evaluated on 1103P and 101-14MGt plants, own-rooted and grafted with Cabernet Sauvignon, in three different water deficit conditions (80, 50, and 20% soil water content, SWC). Gas exchange parameters, stem water potential, root and leaf ABA content, and root and leaf transcriptomic response were investigated. Under well-watered conditions, gas exchange and stem water potential were mainly affected by the grafting condition, whereas under sever water deficit they were affected by the rootstock genotype. Under severe stress conditions (20% SWC), 1103P showed an "avoidance" behavior. It reduced stomatal conductance, inhibited photosynthesis, increased ABA content in the roots, and closed the stomata. The 101-14MGt maintained a high photosynthetic rate, limiting the reduction of soil water potential. This behavior results in a "tolerance" strategy. An analysis of the transcriptome showed that most of the differentially expressed genes were detected at 20% SWC, and more significantly in roots than in leaves. A core set of genes has been highlighted on the roots as being related to the root response to drought that are not affected by genotype nor grafting. Genes specifically regulated by grafting and genes specifically regulated by genotype under drought conditions have been identified as well. The 1103P, more than the 101-14MGt, regulated a high number of genes in both own-rooted and grafted conditions. This different regulation revealed that 1103P rootstock readily perceived the water scarcity and rapidly faced the stress, in agreement with its avoidance strategy.

The Rootstock Genotypes Determine Drought Tolerance by Regulating Aquaporin Expression at the Transcript Level and Phytohormone Balance.

Grapevine rootstocks may supply water to the scion according to the transpiration demand, thus modulating plant responses to water deficit, but the scion variety can alter these responses, as well. The rootstock genotypes' effect on the scion physiological response, aquaporin expression, and hormone concentrations in the xylem and the leaf was assessed under well watered (WW) and water stress (WS) conditions. Under WW, vines grafted onto 1103P and R110 rootstocks (the more vigorous and drought-tolerant) showed higher photosynthesis (AN), stomatal conductance (gs), and hydraulic conductance (Khplant) compared with the less vigorous and drought-sensitive rootstock (161-49C), while under WS, there were hardly any differences between vines depending on the rootstock grafted. Besides, stomatal traits were affected by drought, which was related to gs, but not by the rootstock. Under WS conditions, all VvPIP and VvTIP aquaporins were up-regulated in the vines grafted onto 1103P and down-regulated in the ones grafted onto 161-49C. The 1103P capability to tolerate drought was enhanced by the up-regulation of all VvPIP and VvTIP aquaporins, lower ABA synthesis, and higher ACC/ABA ratios in leaves during WS compared with 161-49C. It was concluded that, under WW conditions, transpiration and stomatal control were rootstock-dependent. However, under WS conditions, alterations in the molecular components of water transport and hormone concentration of the scion resulted in similar gas exchange values in the studied scions grafted onto different rootstocks.

Scion/Rootstock Interaction Studies for Quality Traits in Mango (Mangifera indica L.) Varieties

To explore the quality rootstocks which impart better quality fruits in mango varieties, we studied the interactive effect of the scion and rootstock using five mango varieties (Mallika, Amrapali, Dashehari, Pusa Arunima, and Pusa Surya) grafted on three rootstocks (Olour, Kurukkan, and K-5). A total of 25 physico-chemical parameters were studied in the five grafted varieties viz., fruit weight, yield efficiency, fruit per plant, pulp percent, total soluble solids (TSS), acidity, physiological loss in weight (PLW), peel thickness, respiration rate, etc., and were found to be altered through scion–rootstock interaction. Among the five mango varieties, Olour rootstock proved best to improve the fruit quality and shelf life using the grafting approach. Physico-chemical-traits-based clustering was unable to precisely group scion varieties according to their grafting rootstock. A total of 35 shelf-life specific markers were designed from ripening genes, such as expansin, polygalactouranase, ethylene insensitive, ethylene sensitive, etc. Of these specific primers, 24 showed polymorphism among the studied genotypes. The gene diversity (GD), allele per locus (An), polymorphism information content (PIC), and major allele frequency (MAF) observed were 0.43, 2.00, 0.34, and 0.63, respectively. Cluster analysis clearly showed that scion grafted on Kurukkan and Olour rootstock, and scion varieties grafted on K-5 rootstock grouped together have more similarity. A total of eight simple sequence repeats loci (SSRs) markers were associated with eight physiological traits. Strong association of SSR loci NMSLC-12 and NMSLC-14 with yield efficiency and fruit weight were observed with a phenotypic variance of 85% and 70%, respectively.

Response of grafts of different scion varieties on the different rootstock of mango (Mangifera indica L.) under nursery conditions

The investigation was carried out at the College of Horticulture, Bidar to study the “Performance of grafts of different scion varieties on the different rootstock of mango (Mangifera indica L.) under nursery conditions” with thirty-six treatments comprising of twelve rootstocks (Kurukkan, Kitchner, Olour, EC-95862, Kensington, Peach, Nekkare, Muvandan, Bappakai, Mylepelian, Starch and Local) and three scions (Baneshan, Dashehari and Kesar). Among different rootstocks, Nekkare registered minimum days for sprouting, maximum sprout length, graft success, the height of grafted plant and number of leaves per graft (12.47 days, 6.08 cm, 89.17%, 29.4 cm and 18.33 respectively) whereas the maximum scion girth and root-collar diameter was registered with Bappakai (5.67 and 6.57mm respectively). In scion varieties Kesar recorded minimum days for the emergence of sprouts (15.92 days), maximum sprout length (5.39 cm), graft success (85.83 %), the height of grafted plant (26.74 cm), scion girth (5.55 mm) and root-collar diameter (6.51mm). In the case of different rootstock scion combinations, Nekkare grafted with Kesar recorded a minimum number of days taken for sprouting (11.4 days), maximum sprout length (7.15 cm), graft success (95 %), the height of grafted plant (33.55 cm) and several leaves per graft (19.7) whereas, scion girth and root-collar diameter were found non-significant.

Scion–Rootstock Relationship: Molecular Mechanism and Quality Fruit Production

Most tree fruits are commercially grown on different root systems, hence called composite plants. The section provides the root system as the rootstock, and the atop ground portion is called the scion. The combination is selected based on different traits of scion varieties, rootstock, and prevailing edaphic situations. The dated back plant propagation technique of joining two plants (grafting/budding) that directly communicates new physiological traits to the desirable scion variety from the rootstock remains unclear. In spite of this, this propagation technique continues widely applied in the multiplication of several fruit plant species. In a grafted plant, rootstocks impacted the scion variety’s growth, yield and quality attributes, physiology, nutrient accumulation as well as biotic and abiotic stress tolerance in many ways. Modern research in plant science for next-generation sequencing providing new vital information about the molecular interactions in composite plants multiplied using grafting. Now it was confirmed that genetic exchange is occurring between rootstock and scion variety through grafting joints. In this aspect, we discuss the process and the molecular mechanism of rootstock scion interactions. This review finally explains the dynamics of rootstock–scion interactions as well as their effect on physiology in terms of production, environmental stresses, and fruit quality. The morphological, physiochemical, and molecular mechanisms have been reviewed to develop an integrated understanding of this unknowable process that questions existing genetic paradigms. The present review summarizes the reported molecular mechanism between scion and rootstock and the impact of rootstocks on the production biology of scion varieties of economically important fruit crops and identifies numerous key points to consider when conducting rootstock scion interaction experiments. Rootstocks may offer a non-transgenic approach to rapidly respond to the changing environment and expand agricultural production of perennial fruit crops where grafting is possible in order to meet the global demand for fruit, food, and demands of the future.