Troyer Citrange Research Articles

Characterization of Citrus × Poncirus Embryo Rescued Hybrids as Rootstock Candidate using Morphological Markers

In generally, there are both of nucellar and zygotic embryos in the citrus seeds after cross breeding. Since genetic variations are very important for success of plant breeding, morphological traits of individuals are evaluated to identify diversity. The present study aimed to characterization of citrus hybrids for new rootstock genotypes based on its morphological characters at seedling stage. A total of 335 putative interspecies hybrids, derived from 3 crosses [Common sour orange (Citrus aurantium L.) × Troyer citrange (Citrus sinensis L. × Poncirus trifoliata L.), Common mandarin (Citrus deliciosa Ten.) × Troyer citrange (Citrus sinensis L. × Poncirus trifoliata L.) and King mandarin (Citrus nobilis L.) × Carrizo citrange (Citrus sinensis L. × Poncirus trifoliata L.)], were observed by their plant morphology. The eight qualitative and five quantitative characteristics of hybrid plants such as seedling growth, leaf and thorniness characteristics were evaluated. The average plant height of the population was found between 70.2 cm and 133.2 cm. The average stem diameter varied between 5.9 mm and 8.0 mm. Hybrid seedlings were separated on the basis of dominant trifoliate leaf marker. There was wide diversity among the accessions with respect to quantitative leaf characters. In terms of leaf division, 268 genotypes have bifoliate and 67 were trifoliate in all combinations, and many intermediate forms were also observed. In addition 66 of the genotypes were thornless while 269 of the genotypes were thorny. The genotype No. 4, has been assessed as triploid, from Common mandarin × Troyer citrange combination, has the longest and dense spines. Morphological markers data were analysed by clustering method to compare similarities of hybrids. The dissimilarity index was observed between 0.004 and 17.318 within three hybridization combinations. The hybrids obtained at 110 days after pollination were more distant relative to each other all hybridization combination.

Proline accumulation and antioxidant response are crucial for citrus tolerance to UV-B light-induced stress.

Plants face a wide range of biotic and abiotic stress conditions, which are further intensified by climate change. Among these stressors, increased irradiation in terms of intensity and wavelength range can lead to detrimental effects, such as chlorophyll degradation, destruction of the PSII reaction center, generation of ROS, alterations to plant metabolism, and even plant death. Here, we investigated the responses of two citrus genotypes, Citrus macrophylla (CM), and Troyer citrange (TC) to UV-B light-induced stress, by growing plants of both genotypes under control and UV-B stress conditions for 5 days to evaluate their tolerance mechanisms. TC seedlings had higher sensitivity to UV-B light than CM seedlings, as they showed more damage and increased levels of oxidative harm (indicated by the accumulation of MDA). In contrast, CM seedlings exhibited specific adaptive mechanisms, including accumulation of higher levels of proline under stressful conditions, and enhanced antioxidant capacity, as evidenced by increased ascorbate peroxidase activity and upregulation of the CsAPX2 gene. Phytohormone accumulation patterns were similar in both genotypes, with a decrease in ABA content in response to UV-B light. Furthermore, expression of genes involved in light perception and response was specifically affected in the tolerant CM seedlings, which exhibited higher expression of CsHYH/CsHY5 and CsRUP1-2 genes. These findings underscore the importance of the antioxidant system in citrus plants subjected to UV-B light-induced stress and suggest that CsHYH/CsHY5 and CsRUP1-2 could be considered genes associated with tolerance to such challenging conditions.

Fruit maturity evolution of Clementine Mandarin variety (strain 88) grafted on different citrus rootstocks

Abstract. The research was carried out at Ciano Research Station of Lattakia Research Center - General Commission for Scientific Agricultural Research in Damascus in 2019. The fruit maturity evolution of Clementine Mandarin variety (Strain 88) budded on seven citrus rootstocks (Sour Orange, Citrumelo 4475, Citrumelo 1452, Troyer Citrange, Carrizo Citrange, Macrophylla and Cleopatra Mandarin) and planted in 1989 was studied for a period of 84 days, starting from 16th September 2019 to the start of reaping the fruits on 9th December 2019. There were insignificant differences in the average weight increase of the fruit among the studied treatments. Fruit peel thickness significantly increased by (50.15%) in the trees grafted on Macrophylla compared to those grafted on Cleopatra Mandarin, Troyer Citrange and Citrumelo 1452 whose fruit peel thickness increased by (19.21, 9.58 and 2.61%, respectively). The highest increase in total soluble solids (%) was in the trees grafted on Troyer Citrange by (38.10%), while total acids (%) significantly decreased by (18.33%) in the trees grafted on Citrumelo 1452.

Improvement of Citrus Rootstock Hybrids Derived by 2x × 2x Intra Crosses with the Aid of Embryo Rescue and Ploidy Detection

Diploid Citrus × Poncirus hybrids have significantly contributed to citrus rootstock evaluation. In Türkiye, common sour orange rootstock is used in many different climates and soil conditions at almost 85% of citrus plantations, but this rootstock is susceptible to Citrus tristeza virus disease. This study was conducted to improve new rootstock genotypes by traditional hybridization. Common sour orange (CSO) and Common mandarin (Citrus deliciosa Ten.) (CM) were crossed with Troyer citrange (TC) while King mandarin (KM) was crossed with Carrizo citrange (CC). Embryos obtained from crosses were taken on 110, 120 and 130 days after artificial pollination (DAP), and were germinated on MT culture media. The embryos of 120 DAP of combinations had the highest germination rate within CSO×TC, 95.15%; CM×TC, 96.25%; KM×CC, 95.23%. The trifoliate rates for each combination at subculture (CSO×TC, 17.40%; CM×TC, 11.11%; KM×CC; 6.17%) were obtained from 110 DAP embryos. Survival rates of the genotypes were ranged between 72.13% and 90.28% in subculture and varied from 40.17% and 64.71% in the greenhouse. As a result of the ploidy analysis by flow cytometry, the nuclear DNA content of diploid genotypes were found between 0.78 pg/2C and 0.93 pg/2C. One of the genotypes derived from CM×TC hybridization on 120 DAP was determinated as a triploid plant.

Rootstock mediated alteration in morphology and photosystem in sweet orange (Citrus sinensis) scion cv. Pusa Sharad under NaCl stress

There is a dearth of rootstock studies on how salinity stress imparts tolerance to the scion cultivar in citrus [Citrus sinensis (L.) Osbeck]. The impact of sodium chloride on sweet orange cv. Pusa Sharad (PS) grafted on 11 different rootstocks i.e. Jatti khatti (JK), X–639 (X9), CRH–12 (C12), NRCC–1 (N1), NRCC–2 (N2), NRCC–3 (N3), NRCC–4 (N4), NRCC–5 (N5), Troyer citrange (TC), CRH–47 (C47) and Cleopatra mandarin (CM) was evaluated at the nursery unit of ICAR-Indian Agricultural Research Institute, New Delhi, during 2019–22. Irrigation water containing 30 and 60 mM of sodium chloride (NaCl) was applied to scion/rootstock combinations in comparison to control (without NaCl) till the onset of salt injury symptoms i.e. 42 days. Under salinity stress, the PS scion grafted onto CM, X9, C47, N1, and N3 rootstocks exhibited minimum reduction in the scion height, leaf area ratio, root to shoot ratio, total chlorophyll content, total carotenoid content, transpiration rate, photosynthesis rate, internal CO2 concentration and stomatal conductance as compared to PS scions grafted onto JK, C12, N2, N4, N5, and TC rootstocks under 60 mM NaCl stress. Results showed that specific rootstock can enhance salt-tolerance potential by increasing pigment content and strengthening the photosystem. PS scions grafted onto CM, C47, X9, N1, and N3 demonstrated greater NaCl tolerance compared to those grafted onto JK, C12, N2, N4, N5, and TC and hence recommended for areas having salinity level up to 60 mM.

Nutritional Performance of Five Citrus Rootstocks under Different Fe Levels.

Iron is an essential micronutrient for citrus, playing an important role in photosynthesis and yield. The aim of this paper was to evaluate the tolerance to Fe deficiency of five citrus rootstocks: sour orange (S), Carrizo citrange (C), Citrus macrophylla (M), Troyer citrange (T), and Volkamer lemon (V). Plants were grown for 5 weeks in nutrient solution that contained the following Fe concentrations (in µM): 0, 5, 10, 15, and 20. At the end of the experiment, biomass (dry weight-DW), leaf area, total leaf chlorophyll (CHL), and the activity of root chelate reductase (FCR) were recorded. Additionally, the mineral composition of roots (R) and shoots (S) was evaluated. Principal component analysis was used to study the relationships between all parameters and, subsequently, the relations between rootstocks. In the first component, N-S, P-S, Ca-S, Cu-S, Zn-S, Mn-S, Zn-R, and Mn-R concentrations were related to leaf CHL and FCR. Increases in leaf CHL, Mg-R, and DW (shoots and roots) were inversely related to Cu-R, which was shown in the second component. The values obtained were consistent for V10, C15, and C20, but in contrast for S0 and S5. In conclusion, micronutrient homeostasis in roots and shoots of all rootstocks were affected by Fe stress conditions. The Fe/Cu ratio was significantly related to CHL, which may be used to assist rootstock performance.

Influence of Seed Priming with Trehalase Inhibitors on Inducing Salinity Tolerance in Sour orange and Troyer citrange Rootstocks

Influence of Seed Priming with Trehalase Inhibitors on Inducing Salinity Tolerance in Sour orange and Troyer citrange Rootstocks

Long-term performance of grapefruit cultivars on different rootstocks

The present study was conducted to standardize the rootstock(s) for grapefruit cvs. Marsh Seedless andRedblush, suitable to grow commercially in northern India, budded on eight rootstocks. The sour orange andRLC-4 proved to be the vigorous rootstocks for Marsh Seedless (220.32 m3) and Redblush (175.65 m3) cultivars,respectively. The trees of Marsh Seedless were dwarf (51.23 – 52.27m3) on Attani-1 and Attani-2 rootstocks,while statistically similar growth of Redblush (46.52 m3) was observed on Jatti khatti rootstock. Jatti khatti andBillikhichli proved to be the good nutrient accumulators (P, K, and Mg) for Redblush; and Jatti Khati and RLC-4for Marsh Seedless (N, P, and Zn). Billikhichli and sour orange proved to be the sodium excluder rootstocks forboth varieties. RLC-4 and Rough lemon proved to be the most productive rootstocks for Redblush and MarshSeedless, respectively. It was followed by Troyer citrange for both the cultivars. These rootstocks also yieldedthe juiciest fruits in their respective cultivars. Attani-1 and Troyer citrange produced fruits with low acid contentin the tested cultivars of grapefruit.

Insight into Membrane Stability and Physiological Responses of Selected Salt-Tolerant and Salt-Sensitive Cell Lines of Troyer Citrange (Citrus sinensis [L.] x Citrus trifoliata [L.] Raf.) under Salt Stress

The aim of this study was to evaluate the membrane integrity and some physiological responses of rootstock citrus calli under exposure to different concentrations of NaCl. Selected salt-tolerant cell lines were compared with salt-sensitive calli of Troyer’s citrange (Citrus sinensis [L.] x Citrus trifoliata [L.] Raf.) (TC) with respect to growth, water content, Na+, K+ and Cl− ion content as well as cell membrane stability under exposure to different NaCl concentrations. The results show that the stressed sensitive lines have a consistently high ion efflux. The values recorded for these sensitive calli are 3 to 6 times higher than those of the tolerant calli. Thus, only selected halotolerant calli were able to maintain the integrity of their membranes under salt stress conditions. In the sensitive calli, NaCl always induces a slowing down of growth even from 4 g L−1, and the reduction in the relative growth rate is higher than 50% and reaches more than 90% for the three culture durations at 8 g L−1 NaCl. For the salt-tolerant selected lines, the relative growth rate seems to be slightly slowed down until the second month of culture but becomes equal to that of the control at the third month, whether at 4 or 8 g L−1 NaCl. At the end of the third month, the relative growth rate of the selected calli is 100% at 8 g L−1 NaCl. The water content is twice as high in the selected tolerant calli as in the sensitive ones after three months of salt treatment at 8 g L−1 NaCl. After long-term culture, the halotolerant calli absorbed similar or even higher amounts of Na+ and Cl− than the salt-sensitive lines. However, by the 3rd month, the recorded accumulation rate dropped in the unselected but continued to increase in the tolerant calli (4-fold higher at 12 g L−1 NaCl than the control). Furthermore, exposure of both types of calli (salt-sensitive and salt-tolerant) to equal concentrations of NaCl resulted in greater loss of K+ by the NaCl-sensitive lines. However, for tolerant lines, K+ uptake is not affected at 4 g L−1 NaCl and the decrease in tissue content is less than 25% at 8 g L−1 NaCl. From this observation, it can be concluded that growth and the ability to retain high levels of internal K+ are correlated.

Comparison of Fruit Quality, Leaf Fall during Winter, Water Flow Rate of Root and Tree Growth in Tankan onto Troyer Citrange and Trifoliate Orange

Comparison of Fruit Quality, Leaf Fall during Winter, Water Flow Rate of Root and Tree Growth in Tankan onto Troyer Citrange and Trifoliate Orange

Microbial Inoculants Modulate Physiological Behaviour Of Troyer Citrange Under Drought Stress

A study was undertaken with Troyer citrange (Citrus sinensis × Poncirus trifoliata), the rootstock of citrus, to elucidate the interaction effects of arbuscular mycorrhizal fungi and plant-growth-promoting bacteria on plant physiology under both ample watered and water stress conditions. The result exhibited significant influence of Glomus intraradices and phosphorus solubilising bacteria (PSB) (mixture of Bacillus subtilis and B. megatherium) on plant growth due to root-fungus-bacteria interaction leading to reduced accumulation of reactive oxygen species, production of antioxidant metabolites, higher anti-scavenging enzymes and higher acquisition of plant nutrients, besides enhancing rhizosphere microbial activity. Thus, Troyer citrange could be co-inoculated with G. intraradices and PSB during propagation for healthy growth of the seedlings thereby pre-ponding the budding and subsequent establishment of composite plants under field conditions. Bangladesh J. Bot. 50(3): 467-474, 2021 (September)

Performance evaluation of Fremont mandarin on different rootstocks under the hot arid environment of India

Performance of an inter-specific hybrid Fremont mandarin was assessed on different rootstocks in the hot arid regions of India as a potential scion species to expand citrus fruit availability in an arid region. Fremont scion attained superior growth and yield characteristics on Karna khatta rootstock by displaying the greatest plant canopy parameters followed by Rough lemon rootstock. However, the Pectinifera as well as the Troyer citrange resulted in dwarfness of the scion. The scion-rootstock compatibility indicators such as scion rootstock ratio, stionic difference and TCSA which were greatest in the Fremont/Pectinifera combination, confirm that the inhibited tree growth on Pectinifera rootstock was caused by intrinsic features of the rootstock rather than an incompatibility reaction. Furthermore, Karna khatta rootstock resulted in highest fruit yield and related traits followed by Rough lemon and Pectinifera rootstocks. The Pectinifera rootstock resulted in a similar response to all fruit physical attributes i.e., fruit weight, fruit diameter, fruit index and fruiting density, except fruit number. The fruit maturity of Fremont was obtained earliest on Pectinifera, while it was most delayed on Karna khatta and Rough lemon rootstocks. Fruit quality parameters on Pectinifera rootstock were superior to those of common rootstock species (Rough lemon or Karna khatta) including fruit juice content as well as its nutritional constituents like TSS, ascorbic acid, pH, total sugar, organoleptic taste, ripening index, lower content of acidity and rind thickness. The total AAE, total flavonoids, total phenol contents were also noticeably higher than those obtained on other rootstocks, except Troyer citrange. Overall, Fremont mandarin can be considered a promising scion in arid regions to extend the harvesting period of superior quality fruits, especially on dwarfing Pectinifera rootstock. It would further ease harvesting operations vis-a-vis possible attainment of a better micro-climate due to small tree stature and high-density orcharding.

Influence of Endogenous Plant Hormones on Physiological and Growth Attributes of Kinnow Mandarin Grafted on Nine Rootstocks

Citrus holds the key position in horticulture sector of Pakistan in terms of area and production. Kinnow is considered as the trademark of Pakistan’s citriculture industry. Cultivation experiment was conducted to evaluate the endogenous plant hormones, leaf gas exchange, photosynthetic pigments, vegetative performance, and yield of Kinnow mandarin grafted on nine rootstocks (Rough lemon, cox mandarin, Fraser hybrid, Troyer citrange, Cleopatra mandarin, Poncirus trifoliata, Benton, C-35, and Carrizo citrange). Maximum indole acetic acid (IAA), gibberellic acid (GA3), and zeatin (ZT) levels were recorded in scion and rootstock of Poncirus trifoliata followed by Fraser hybrid. Troyer citrange rootstock depicted maximum amount of abscisic acid in scion and rootstock. Maximum leaf gas exchange in Kinnow mandarin was recorded on Fraser hybrid rootstock. Kinnow grafted on Troyer citrange rootstock had minimum stomatal conductance and photosynthetic activity because of high ABA level. Photosynthetic pigments of Kinnow mandarin were maximum on Poncirus trifoliata and minimum on Troyer citrange. A positive correlation was observed among the levels of IAA, GA, ZT, and vegetative growth of Kinnow mandarin. It is concluded that endogenous hormones modulated the growth of Kinnow mandarin. Poncirus trifoliata and Fraser hybrid rootstocks could be an alternate rootstocks of traditional Rough lemon for Kinnow mandarin.

<p><strong>Tolerance mechanism in hybrid citrus rootstock progenies against <em>Phytophthora nicotianae</em> Breda de Haan</strong></p>

Phytophthora species is the major threat for world citrus industry in general, and for India, in particular due to commercial use of susceptible rootstocks. The resistant gene possessed by Poncirus genus may be of immense use, if transferred in a well acclimatized citrus species which can have good impact on fruit size of scion varieties. Being a soil borne problem, development of resistant/tolerant rootstock(s) is the most eco-friendly solution to combat with this deadly disease. The present study was conducted during 2016 to understand the tolerance mechanism in the intergeneric hybrids of citrus rootstocks against Phytophthora nicotianae. The materials of study consisted of 30 hybrids, ten each of Pummelo (P) × Troyer (T), Pummelo (P) × Sacaton (S) and Pummelo (P) × Trifoliate orange (TO) were tested against the inoculation of P. nicotianae, taking Pummelo, Troyer and Citrumelo as control treatments. Of the total hybrid progenies, only six hybrids (P × TO-103, P × TO- 112, P × S-117, P × S-119, P × T-125 and P × T-130) expressed resistance against P. nicotianae on the basis of lesion length (nil or <2.5 cm). Of the tested hybrids, P x S-117 had the highest photosynthetic rate (A) (8.12 µmol m-1s-1) followed by P × TO-112 and P × S-119. Excised leaf water loss (ELWL) was lowest in P × S -119 (7.47%) without having significant diference with Troyer citrange, and rest of the resistant hybrids. The highest relative leaf water content (RWC) was registered in P × T-125 (84.47%), which was similar statistically with P × T-119, P × T-103 and P × T-112 (77.59-83.42%) hybrids. Hybrid P × S -117 tended to show the highest total chlorophyll content (12.14 mg g-1FW), followed by P × TO-112 and P × T-127. P × S-117 expressed the lowest level of hydrogen peroxide (100.72 mM mg-1 FW) without having any significant difference with those of P × TO-110, P × T-127 and P × T-130 hybrids. The lipid peroxidation was highest in P × T-132 (25.99 µmol g-1 FW), while its lowest accumulation was in P × S-119 (6.44 µmol g-1 FW) with statistically similar to P × T-130 hybrid. The highest content of glycine betain was noticed in P × TO-103, P × TO-117 and P × TO-130 (0.33 mg g-1 FW in each). Of the total hybrid progenies, highest accumulation of leaf N was found in P × T-125 (2.74%) followed by P × S -119 and P × T-130. All six resistant hybrids excelled over other hybrids in respect of leaf K+ content. The content of Ca+2 was highest in the leaves of P × S-117 (4.90%) having similarity statistically with P × T-125 (4.87%). The resistance of identified hybrids (P × TO-103, P × TO- 112, P × S-117, P × S-119, P × T-125 and P × T-130) against P. nicotianae was also evidenced by low ROS generation and ELWL, with high RWC and leaf nutrient status over other hybrids. Among the various physicochemical characters studied, only A, ELWL and N were found to have significant but inverse relationship with lesion length caused by Phytophthora inoculation.

Effect of some Citrus Rootstocks Types on Growth and Productivity of Gold Nugget Mandarin Trees

The present investigation was carried out during two successive seasons (2018/2019; 2019/2020) on almost 12-year old identical Gold Nuggettrees(Citrus reticulate, Blanco) (Wilking mandarin x Kincy mandarin), grafted on three rootstocks cultivated in a private orchard located in Al Qalyubia Governorate, Egypt. The trees were grown at a distance of 2 × 6 m in silt soil under the Immersion irrigation system. This investigation aimed to study the effect of some citrus rootstocks on Gold Nugget mandarin trees Growth and Productivity. Three citrus rootstocks were: Troyer citrange Citrus sinensis 'Washington' x Poncirus trifoliate (Tr.), Sour orange (Citrus aurantium L.) (SO.) and Volkamer Lemon (Citrus volkameriana) (VOL). The experiment was designed as a randomized complete block design with five replications. The obtained results showed that Gold Nugget grafted on Troyer citrange rootstock recorded the highest significant values of chlorophyll a, b, total chlorophylls, total carbohydrates, spring growth cycle, fruit set and yield. Whereas Gold Nugget grafted on Sour orange rootstock recorded the highest significant values of shoot thickness, Leaf surface area, Rate Increasing canopy, vitamin C and TSS/ acid ratio. Regarding Gold Nugget grafted on Volkamer lemon rootstock recorded the highest significant values of dray matter percentage, the number of leaves, tree Canopy, summer growth cycle, flowering, fruit Physical properties and acidity percentage.

Young navel orange rootstock improves phosphorus absorption from poorly soluble pools through rhizosphere processes

An increased plant capacity to efficiently use the poorly available pools will be very helpful in citrus production. Information on the various mechanisms evolved by citrus rootstocks to optimize soil phosphorus (P) access is limited. Thus, the objectives of this study were: To evaluate P acquisition efficiency (PAE) in Thomson Navel Orange (Citrus sinensis L. Osbeck.) plants grafted on three rootstocks and adaptive mechanisms developed by each to these rootstocks to increase P uptake in one calcareous soil. For this purpose, a pot experiment was conducted in a completely randomized design with three replications. Treatments consisted of three rootstocks of citrus, including Sour Orange (SO), Swingle Citrumelo (SC) and Troyer Citrange (TC). 18 months after planting seedlings in pots, plants were harvested and the rhizosphere soils were separated. Dissolved organic carbon (DOC), the population of fungi and bacteria, microbial biomass P (MBP), alkaline (AlP) and acid (AcP) phosphatases, available P (P-Olsen), and P fractionation according to the modified Hedley’ sequential fractionation procedure were determined in the rhizosphere soils. After the harvest, P acquisition efficiency of plants (PAE) was determined. The results of this study showed that SO promoted higher scion P uptake and increased PAE. The fungal and bacterial population, MBP, AcP in the SO rhizosphere soils was greater than the SC and TC rhizosphere soils (P < 0.05). P availability closes the root surface of SO rootstock was higher in comparison to the other rootstocks. Moreover, the effect of the rhizosphere on various fractions of P was under rootstock control. The highest amount of exchangeable P and Fe and Al soil P in the rhizosphere soils was found in SO grafting, while the lowest P associated with Ca compounds and residual P in the rhizosphere soils was found in SO-grafting. This necessarily implies the P mobilization of poorly available pools are vital mechanisms for P acquisition by plants on SO in this P-poor soil. In conclusion, the results of the present study showed that different PAE of rootstocks may be associated with the various mechanisms of action of each rootstock involved in P absorption.

Studies on growth, rooting and budding performance of citrus rootstock seedlings

A study was conducted at Punjab Agricultural University, Fruit Research Station, Jallowal-Lesriwal, Jalandhar during 2016-17 to evaluate nursery performance of different exotic rootstocks and their budding compatibility with Kinnow mandarin. The seeds of exotic rootstocks: Swingle citrumelo, Rich 16-6, Rubidoux trifoliate (RTF), US-852, Benton citrange, Troyer citrange, Kuharsuke citrange, C-35 citrange, X-639, Carrizo citrange, Gou Tou, Shin Chu Sha, Rangpur Lime, Volkameriana lemon and Rough lemon were sown in protrays and later transplanted in poly-bags under protected conditions. The results of the experiment revealed that maximum plant height and stem thickness was recorded in C-35 citrange and Swingle citrumelo, respectively. Number of leaves/plant was highest in X-639. Root length and thickness at buddable stage were highest in Volkameriana lemon and Benton citrange, respectively. Fresh and dry root weight was maximum in Rangpur lime rootstock. Kinnow mandarin (<i>Citrus reticulata</i> Blanco) was budded on all the rootstocks under study and highest budding success was recorded in Rough lemon followed by Volkameriana lemon, Rangpur lime and Kuharsuke citrange. It was concluded that Volkameriana lemon, Kuharsuke citrange and Rangpur lime can also be explored as potential rootstocks along with Rough lemon for raising the nursery of Kinnow mandarin under protected conditions in Punjab. However, their long term effects on fruit yield and quality along with stionic compatibility should also be critically taken into consideration before any commercial recommendation.

Seasonal Variations in Mineral Nutrients in Leaves of ‘Nova’ and ‘Robinson’ Mandarins Budded on Different Rootstocks

The characteristics of rootstock have impacts scion’s nutritional status, resistance to environmental stresses and adaptation to a specific region. Thus the performance of a cultivar is largely dependent on the rootstock-scion interactions. In this study, seasonal variations in mineral nutrients of ‘Nova’ and ‘Robinson’ mandarin cultivars budded on different citrus rootstocks were investigated under Dortyol-Hatay (Turkey) ecological conditions. Nitrogen (N), phosphorus (P) and potassium (K) contents of the leaves exhibited slightly similar trends with each other. In general, these nutrients decreased from January to March-April and increased in the subsequent growing season until mid- and late summer, then decreased again until December. Similar trends were also observed in calcium (Ca) and magnesium (Mg) concentrations of leaves. Leaf Ca and Mg concentrations decreased from January to March, then increased during fruit development until July-August and decreased again during autumn and winter. Also, micro elements such as iron (Fe), zinc (Zn), manganese (Mn) and copper (Cu) increased from January to May–June and then gradually decreases began during the growing season until December. Throughout the entire growing season, mean macro nutrients such as N, K and Ca concentrations ranged from 1.89% (‘Nova’/Carrizo citrange) to 2.02% (‘Robinson’/Carrizo citrange), from 1.10% (‘Robinson’/Carrizo citrange) to 1.39% (‘Nova’/Carrizo citrange) and from 2.62% (‘Nova’ /sour orange) to 3.48% (‘Robinson’/Troyer citrange), respectively. Phosphorus and Mg concentrations showed slightly similar trends and varied between 0.14–0.16% and between 0.31–0.39%, respectively. The ranges of mean micro nutrients such as Fe, Zn, Mn and Cu concentrations were between 65.3 and 75.4 mg kg−1, 33.7 and 39.6 mg kg−1, 64.1 and 70.6 mg kg−1, and 10.5 and 11.4 mg kg−1, respectively. It can be concluded that rootstock-scion relations can cause considerable differences in seasonal nutrition of mandarin cultivars.

Rootstocks Influence Yield Precocity, Productivity, and Pre-Harvest Fruit Drop of Mandared Pigmented Mandarin

Citrus fruit quality and scion productivity are influenced by the choice of rootstock. We aimed to evaluate the effect of rootstocks on yield and fruit quality of Mandared, a triploid pigmented mandarin. To do so, we established a rootstock field trial on a high pH soil (8.6) in which Mandared was grafted onto 11 rootstocks. These included some standard rootstocks, such as trifoliate orange ((Poncirus trifoliata (L.) Raf.), Troyer citrange (Citrus sinensis (L.) Osb. × P. trifoliata), Swingle citrumelo (Citrus paradisi Macf. × P. trifoliata), and C35 citrange (C. sinensis × P. trifoliata), as well as new releases from the Council for Agricultural Research and Economics (CREA, Acireale, Italy) and the University of California Riverside (UCR). The cumulative yield was measured over five consecutive years, while fruit quality was analyzed for two years. The trees on C35, C57 (Citrus sunki Hort. ex. Tan. × P. trifoliata), and C22 (C. sunki × P. trifoliata), started to set fruits one year earlier than the others. The trees on C57 provided some of the highest cumulative yields and canopy volumes. The production of Mandared grafted onto C57 was double that of Mandared grafted onto Troyer, while Mandared grafted onto C35 and C22 resulted in the best yield efficiency. The trees on Swingle and C57 significantly reduced the pre-harvest fruit drop, to which Mandared is particularly sensitive. However, grafting Mandared onto Swingle resulted in the highest variation among replicates, probably due to its high sensitivity to iron chlorosis. Most of the fruit quality parameters, such as fruit size, total soluble solids (TSS), and acidity were not significantly different among the rootstock treatments. However, fruits produced by Mandared grafted onto C22 had one of the highest rates of anthocyanin accumulation. The results indicate that C57, C35, and C22 were the most suitable rootstocks for Mandared in South-Eastern Sicily.

Growth and yield of orange (Washington Navel 141) grafted on different citrus rootstocks

Abstract. This investigation was conducted during 2014, 2015 and 2016 in the field of the citrus experimental station in Ciano, the general corps of scientific agricultural researches. The growth and yield of orange trees (Washington navel 141) budded on seven citrus rootstocks (Sour orange, Troyer citrange, Carrizo citrange, Citrumelo 4475, Citrumelo 1452, Macrophylla and Cleopatra mandarin) and farmed since 1989 have been studied. The results for the average of yield showed that the trees grafted on Cleopatra mandarin (58.33 kg. tree-1) were significantly superior to those grafted on Macrophylla (34.17 kg. tree-1). Orange trees grafted on Citrumelo 4475 and Citrumelo 1452 were significantly superior to other treatments in trunk section area of the rootstock (922.41 and 841.02 cm2, respectively). The greatest fruit fresh weight was in trees grafted on Citrumelo 4475 (284.85 g. fruit-1) which were significantly superior to those grafted on Carrizo and Troyer citrange (232.49 and 236.06 g. fruit-1, respectively). The biggest total soluble solids (%) was in trees grafted on Carrizo and Troyer citrange (12.83% for both treatments) which were significantly superior to those grafted on Sour orangе and Macrophylla (11.5% for both treatments), while the greatest total acids (%) was by Sour orange (2.08%) without significant differences.