Sources Of Rootstocks Research Articles

Rootstock potential of auto and Allotetraploid Citron [Citrullus lanatus var. citroides (L. H. Bailey) Mansf.] for Watermelon [Citrullus lanatus var lanatus (Thunb.) Matsum. & Nakai] under hydroponic conditions: plant growth and some physiological characteristics

The emergence of some physiological and fruit quality problems due to the common squash rootstocks used in watermelon has led researchers to search for alternative rootstocks sources. Exploitation of novel Citrullus germplasm such as citronmelon (Citrullus lanatus var. citroides) is an alternative to avoid these problems. In this study, rootstocks potential of auto and allotetraploid citrullus genotypes for watermelon were investigated as regard to plant growth and some physiological parameters under hyroponic conditions. Plant length was significantly affected by rootstock genotype and the longest plant stem was measured in watermelon plants grafted on N7-4T tetraploid rootstock (62.67 cm) while the shortest stem was measured in grafted plants onto autotetraploid Calhounn Gray with 14.33 cm. Among the graft combinations, N7-4T/CT (93.33 g) and CN7-5T/CT 95.00 g) graft combination produced the highest shoot fresh and dry weight. As in shoot fresh weight, the exploitationted on to tetraploid rootstock produced higher root fresh and dry weight than the plants grafted on diploid rootstocks and commercial rootstock. The highest root fresh and dry weight were determined in the plants grafted on to autotetraploid N5-4T and allotetraploid CN7-5T. Root characteristics were significantly affected by rootstock genotypes. The N, P, K and Ca contents of the leaves of the CT watermelon cultivar grafted on different rootstocks were significantly affected by the rootstocks. This study showed that citrullus tetraploid genotypes (auto and allo) to be produced by polyploidy method can be an important alternative rootstock source for watermelon.

Determining Seed Viability During Fruit Maturation to Improve Seed Production and Availability of New Citrus Rootstocks.

In recent years, the pressure for replanting and resetting huanglongbing (HLB or citrus greening) affected citrus groves has led to an inadequate seed supply for the most popular rootstock cultivars in the State of Florida, United States. Early fruit harvesting of citrus rootstock source trees might reduce fruit losses and enhance seed availability, especially in HLB-endemic and hurricane susceptible areas, if the physiological quality of the seeds is adequate. The effects of fruit maturity on seed quality and seedling performance of US-802, US-897, and US-942 citrus rootstocks were investigated for two consecutive growing seasons. The study included the evaluation of seed germination and nursery performance of the citrus rootstock seedlings. The germination test was performed in vitro, where seeds were hand-peeled, surface-sterilized and placed in culture tubes containing basal Murashige and Skoog medium. For the emergence test, seeds were sown in seedling trays containing sterilized growing substrate in a greenhouse with controlled-environment conditions. Rootstock fruits from all three varieties harvested in August and September had seeds with higher germination potential, as more than 90% of the seeds generated seedlings. US-942 had more % of emergence than US-802 and US-897, resulting in faster seed germination; in contrast, US-802 had the faster shoot growth rate. Assays on fruit abscission response showed that by August, fruit from all three varieties were responsive to ethylene and abscised, although response varied and was higher in US-942, suggesting the seeds were mature enough. Taken together, our findings indicate that fruits these three rootstocks can be harvested as early as August in contrast to the current procedures without losing germination potential. This will result in an increase in available seeds for nurseries in Florida.

THE ROLE OF GRAFTING IN IMPROVING THE PRODUCTIVITY OF CUCUMBER UNDER SALINE STRESS CONDITIONS

A greenhouse experiment was carried out during 2017 and 2018 summer seasons at Desert Research Center farm, Ras Sudr, South Sinai. The aim of the experiments was to investigate the effect of different rootstocks and citric acid foliar spray on growth, yield and its components and net income as well as net income diffraction percentage and mineral composition of cucumber plant Safi (F1) hybrid. The foliar spray of citric acid was four concentrations (0, 200, 300 and 400 ppm) and the grafting treatments were check nongrafted, Safi (F1) grafted onto Shentoza or on Coplt rootstocks (Cucurbita moschata Duch.). Strip plot design was used where main plots were assigned for foliar spray and sub plots for grafting. Results showed that grafting increased plant growth, yield and its components, marketable yield, net income and net income diffraction percentage. The increasing was differing according to rootstock source. Grafting, also, increased leaf chlorophyll and fruit potassium and calcium content while sodium content was decreased. The highest values of all measured parameters were obtained, in general, with cucumber plants grafted onto Shentoza rootstock. As for citric acid effects, results indicated that its application increased all parameters except sodium content; the highest values were obtained with cucumber plants sprayed with citric acid at rate 400 ppm. As for the combination between grafting technic and citric acid concentration, the best growth and highest yield and its components were obtained with the cucumber plants grafted onto Shentoza rootstock combined with the highest concentration of citric acid. Also, leaf chlorophyll and potassium of fruits recorded the highest increases, whereas fruit calcium and sodium were not significantly affected

Ceratocystis canker resistance in BC1 populations of interspecific hybridization of fig (Ficus carica) and F. erecta

Ceratocystis canker is a serious disease in fig (Ficus carica L.) caused primarily by the soil borne fungus Ceratocystis ficicola. The disease mainly invades the roots and trunks of figs, eventually killing the tree. Ficus erecta and F1 (F. carica × F. erecta) were found to be extremely resistant to this fungus. F. erecta is not practical as a rootstock due to extremely low grafting compatibility with F. carica between F. carica. F1 hybrids had been found to be unusable as a rootstock because of a root disorder. Then, we performed backcross hybridizations (BC1) between four common figs (seed parent) and F1 caprifig type (pollen parent) through artificial pollination. The leaf morphology of BC1 progeny was similar to that of F. carica rather than those of F. erecta or F1. Hardwood and softwood cuttings of BC1 progeny readily rooted. BC1 populations were inoculated with C. ficicola by direct wounding of the shoot. The segregation ratios of resistance and susceptibility in BC1 populations were consistent with a 1:1 Mendelian model. In a wound inoculation experiment using cuttings from 4 BC1 individuals identified as being disease resistant, all examined lines were healthy and unwithered 100 days after inoculation. This result suggests that Ceratocystis canker resistance in F. erecta is controlled by a single dominant gene. BC1 progeny exhibited sufficient graft compatibility with fig, indicating that Ceratocystis canker-resistant BC1 would be a practical fig rootstock source.

Genetic diversity of Cucurbita rootstock germplasm as assessed using simple sequence repeat markers

Grafting is becoming more popular in cucurbit crop production for soil-borne disease control. The correct choice of rootstock can have a vital role in the success of grafting. An improved understanding of the genetic diversity and potential of rootstock germplasm can be expected to contribute to more efficient breeding for improved rootstocks. Cucurbita spp. (squash and pumpkins) are major sources of rootstocks for grafting cucumbers, melons, and watermelons. The genetic diversity and relatedness of 25 commercial Cucurbita rootstock cultivars and 10 inbred lines were assessed using 80 simple sequence repeat (SSR) markers in this study. Forty-one SSR loci yielded 94 polymorphic alleles, with an average of 2.29 alleles per locus. The polymorphism information content values ranged from 0.16 to 0.60, with an average of 0.36. Cluster analysis and principal coordinate analysis showed that the majority of commercial Cucurbita rootstocks are interspecific hybrids, C. maxima×C. moschata, and these hybrids are closely related. By contrast, the C. moschata inbreds exhibit considerably greater genetic diversity, suggesting that they could be useful for rootstock improvement.

Co‐infection by Botryosphaeriaceae and Ilyonectria spp. fungi during propagation causes decline of young grafted grapevines

Decline of newly planted, grafted grapevines is a serious viticultural problem worldwide. In the Riverina (New South Wales, Australia), characteristic symptoms include low fruit yields, very short shoots and severely stunted roots with black, sunken, necrotic lesions. To determine the cause, roots and wood tissue from affected plants in 20 vineyards (Vitis vinifera cv. Chardonnay grafted to V. champini cv. Ramsey rootstock) were assayed for microbial pathogens. Ilyonectria spp. (I. macrodidyma or I. liriodendra, producers of phytotoxin brefeldin A, BFA, and cause of black foot disease of grapevines) and Botryosphaeriaceae spp. (predominantly Diplodia seriata) were isolated from rootstocks of 100 and 95% of the plants, respectively. Togninia minima and Phaeomoniella chlamydospora (cause of grapevine Petri disease) were isolated from 13 and 7% of affected plants, respectively. All Ramsey rootstock stems of grafted plants sampled from a supplier nursery were infected with Ilyonectria spp. and D. seriata. Diplodia seriata, but not Ilyonectria spp., was also isolated from 25% of canes sampled from the rootstock source block. Root inoculation of potted, disease‐free Chardonnay plants with Ilyonectria isolates from diseased vineyards caused typical disease symptoms, while co‐inoculation with Botryosphaeriaceae spp. increased disease severity. This is the first study to show that a major cause of young grapevine decline can be sequential infection by Botryosphaeriaceae from rootstock cuttings and Ilyonectria spp. from nursery soil. Although the Petri disease fungi were less common in young declining grafted grapevines in the Riverina, they are likely to contribute to the decline of surviving plants as they mature.

An efficient micropropagation protocol for Citrus jambhiri Lush. and assessment of clonal fidelity employing anatomical studies and RAPD markers

Citrus jambhiri (rough lemon) is considered a major rootstock source for a number of Citrus species. A simple method for micropropagation from nodal segments is reported. Nodal segments of C. jambhiri were inoculated on MS medium supplemented with different concentrations and combinations of 6-benzylaminopurine (BAP), kinetin, and N6-(2-isopentenyl) adenosine (2iP). Maximum multiple shoot regeneration response (75 %) was observed with BAP at 3 mg l−1. Shoots were multiplied for 30 d on fresh medium with similar composition. A total of 67 % of the cultures showed multiplication with the optimum number of shoots (4.02) and height of shoots (1.81 cm) with BAP (3 mg l−1) alone. Maximum rooting response (87 %) was observed with naphthaleneacetic acid at 0.5 mg l−1. Transverse sections of shoot stems obtained in vivo (sampled from seedlings) and in vitro (regenerated from nodal segments), showed similar anatomies. Randomly amplified polymorphic DNA analysis confirmed that all the regenerated plants were genetically identical to their donor plant, suggesting absence of detectable genetic variation in the regenerated plantlets.

Interspecific hybridization of fig (Ficus carica L.) and Ficus erecta Thunb., a source of Ceratocystis canker resistance

Ceratocystis canker, which is caused by the fungus Ceratocystis fimbriata Ellis et Halsted, is one of the most severe diseases of the common fig (Ficus carica L.). In contrast, the wild fig species F. erecta Thunb. is resistant to this fungus. We performed interspecific hybridization between the common fig (seed parent) and F. erecta (pollen parent) through artificial pollination. Even though hybrid seeds showed high germination rates, the seedling survival rates were low. All of the seedlings contained the expected simple sequence repeat (SSR) alleles from both common fig and F. erecta at each of the three loci tested, thus confirming the parent–offspring relationships of the interspecific hybrids. The leaf morphological characters of hybrid seedlings were intermediate between those of the parents. Cuttings of cultivars of common fig, F. erecta, and hybrid seedlings were inoculated with C. fimbriata by direct wounding of the shoot. All of the common fig cultivars tested withered and died within 10 weeks. Leaves and shoots of the hybrids and F. erecta were healthy 100 days after inoculation. Our results suggest that interspecific hybridization between the common fig and the wild species F. erecta is a breakthrough in the breeding of a new fig rootstock source with resistance to Ceratocystis canker.

(108) Early Flower Bud Production and Field Establishment of Two Pawpaw Cultivars on Five Seedling Rootstocks

The pawpaw [Asimina triloba (L.) Dunal] is native to the southeastern United States and has potential as a new tree fruit crop. Clonal rootstocks are not currently available for pawpaw cultivars; therefore, nurseries graft cultivars onto rootstock derived from locally available seed. Great variation in rootstock vigor with this seedstock can result in grafted trees that lack vigor and have delayed fruit production. Pawpaw rootstocks that promote precocity would be desirable to growers. The objectives of this study were to determine if rootstock source and pruning system influenced precocity and field establishment of two pawpaw cultivars. In May 2004, a rootstock trial was planted at the Kentucky State University Research Farm that consisted of `Sunflower' and `Susquehanna' budded onto five seedling rootstocks (PA-Golden, Sunflower, Susquehanna, K8-2, and commercially available seed) with either a minimal or central leader pruning system. There were eight replicate blocks with each treatment combination, for a total of 160 trees. In Fall 2005, field mortality was greatest (58%) for `Susquehanna' budded onto Susquehanna seedling rootstock, whereas mortality was about 25% with other scion/rootstock combinations. The number of flower buds present on each tree was evaluated in Feb. 2006. Rootstock and pruning method did not influence the number of trees exhibiting flower buds. However, cultivar did influence the number of trees with flower buds; more trees of `Sunflower' (48%) had flower buds than `Susquehanna' (8%), and `Sunflower' (3.46) had more flower buds per tree than Susquehanna (0.43). Pruning system did influence the number of flower buds per tree; minimal pruned trees (2.65) had more flower buds per tree than central leader (1.21) trained trees.

New in vitro micrografting method for apple by sticking

The requirements for in vitro micrografting in apple are described. In vitro multiplicated shoots of cv. Royal Gala were the sources of rootstocks and scions after different pre-treatment, respectively. Oxidative browning of cut surfaces could be inhibited by the use of antioxidant mixture during grafting process. Scion base cut in v-shape was stuck by 1% agar-agar solution into the vertical slit of rootstock. There was no any displacement and the rate of fused and further developed grafts was 95 percent. Agar-agar between the rootstock and scion made the transport of different materials possible and hold the graft units together until the fusion took place. Fusion was proved also by histological studies. Some of in vitro micrografts were planted and acclimatisated and the survival was 100 percent.

Effects of Rootstock Source on the Size, Cone Production, and Compatibility of Douglas-Fir Grafts

Abstract Scions of coastal Douglas-fir (Pseudotsuga menziesii) were grafted on rootstock from coastal, northern interior and southern interior origin. Data on ramet size, cone production, and graft compatibility were collected. Twelve years after grafting significant differences for most crown and stem traits were found among the rootstock sources, with coastal rootstock resulting in the fastest scion growth. Northern interior rootstock sources produced larger grafts than southern interior rootstock. Significant graft union appearance and cone production differences were not detected, but coastal sources consistently had higher graft compatibility and healthier unions. It is concluded that, for coastal Douglas-fir, the use of a vigorous coastal rootstock source that promotes fast growth in the scion, and has high graft compatibility potential, is the most desirable for coastal locations. This will result in fewer losses due to graft incompatibility, faster crown development, more options for crown management and increased cone production potential. West. J. Appl. For. 7(3):73-77.

Rapid Production Methods for Ottawa-3 Rootstock and Branched Apple Nursery Stock

A system for the rapid production of Ottawa-3 (0.3) rootstock (Malus domestica Borkh.) and branched apple nursery stock in the greenhouse is described. The time required for production of a finished' tree, ≈1 year, compared favorably with traditional methods. Cuttings derived from tissue-cultured 0.3 rootstocks rooted well (up to 94% success rate), and the rooting effect persisted in cuttings from tissuecultured rootstocks grown for 1 year in the field. All combinations of two levels of N and P in a Long Ashton nutrient solution were applied weekly to pots containing either tissue-cultured rootstocks or cuttings. The growth rate of tissue-cultured rootstocks exceeded that of cuttings. The growth rate of both sources of rootstocks increased in response to added P and N. Growth of scion shoots (`Royal Gala') increased in response to N. Branch production of `Royal Gala' was greater for trees with the higher P and N rates. Trees on tissue-cultured rootstocks had more branches than those on cuttingderived roostocks at the higher level of N.

A Comparison Between Healthy and Leafroll-Affected Grapevine Planting Stocks

A vineyard trial set in 1968 at Davis, California, to compare performance of commercial, non-certified Burger scions and Dogridge rootstocks from Lodi, California with certified Burger scions and Dogridge rootstocks from the Foundation Vineyard at Davis in a factorial experiment became a comparative study between healthy and leafroll-affected grapevines. Indexing showed that the non-certified Burger scion wood was infected with leafroll virus; the Burger scion wood from Davis and both sources of Dogridge were free of virus. Vines developing from noncertified Burger scions on either rootstock source were leafroll-affected. Those developing from healthy scions on either rootstock source were leafroll-free. With full crops, the healthy vines were superior to leafroll-affected ones in growth, yield and sugar content of the fruit. With approximately 50 percent crop reduction, the rate of sugar accumulation in the leafroll affected vines was equal to that in the fully-cropped, healthy vines. Regardless of crop or sugar level, the acidity of the fruit of leafroll-affected vines was higher than that of healthy vines at any given date during the ripening period.