Rootstock Grafting Research Articles

The JatrophaFT ortholog is a systemic signal regulating growth and flowering time

Jatropha curcas is being promoted as a new bioenergy crop in tropical and subtropical regions due to its high amount of seed oil and its potential capacity to grow on marginal land for biofuel production. However, the productivity of the plant is constrained by the unfavorable flowering time and inflorescence architecture, which render harvesting of seeds time-consuming and labor-intensive. These flowering-related traits have limited further widespread cultivation of Jatropha. We identified a Jatropha curcas homolog of Flowering locus T (JcFT) and demonstrated its function by genetic complementation of the Arabidopsis ft mutant. The JcFT expression level was found to be remarkably correlated with leaf age. Overexpression of JcFT in Jatropha reduced flowering time and altered plant architecture by producing more branches. Grafting experiments suggested that the earlyflowering and alteration of plant architecture traits were graft-transmissible. We also showed that the FT-overexpressing transgenic Jatropha can be used as a root stock for grafting of scions derived from other Jatropha. We generated early flowering transgenic Jatropha plants that accumulate higher levels of the florigen FT. Not only early flowering but also plant growth was affected in JcFT overexpression lines. More seeds can be produced in a shorter time frame by shortening the flowering time in Jatropha, suggesting the possibility to increase seed yield by manipulating the flowering time.

Rootstock Grafting Helps Improve Main Metal Nutrient Translocation of Bleeding Sap in Muskmelon

This paper was focused on the discussion about the main metal nutrients translocation in bleeding sap during muskmelon development and it was improved by rootstock grafting. The total translocation volume of metal nutrients in bleeding sap of each treatment depicted the same trend where G1 (Zhongmi 1/Riben Strong) and G3 (Zhongmi 1/Shengzhen 1) improved the supply capacity of metal nutrients to the aboveground parts and there were no concentration and translocation volume changes for each metal ion in bleeding sap with dissimilar rootstocks grafting when G1 and G3 improved the supply capacity of potassium, natrium, calcium, magnesium, ferrum, cuprum and zinc to the over ground parts from the root system, and furthermore G2 (Zhongmi 1/Quanwang) and G3 reduced manganese translocation in bleeding sap significantly on 10 DAA (days after anthesis) and manganese translocation in G1 and G3 during 20 to 30 DAA were remarkably higher than that in CK and G2, while manganese translocation in G3 was notably higher than that in the other treatments on 40 DAA. So based on the main metal nutrient supply capacity of the root system for comprehensive considerations, G1 and G3 were superior scion/rootstock combinations for top quality and high yield potential.

Rootstock and fruit canopy position affect peach [Prunus persica (L.) Batsch] (cv. Rich May) plant productivity and fruit sensorial and nutritional quality

The right combination of rootstock and training system is important for increased yield and fruit sensorial and nutritional homogeneity and quality with peach [Prunus persica (L.) Batsch]. We investigated the effects of rootstock and training system on these parameters, testing the effect of vigorous GF677 and weaker Penta∗ rootstock on ‘Rich May’ peach cultivar. Fruit position effects regarding photosynthetically active radiation availability, along the canopy profile using the Y training system, were investigated. The positive relationships between total polyphenols content and antioxidant capacity according to canopy vigour and architecture were determined for the two scion/stock combinations. Changes in fruit epicarp colour and content of bioactive compounds were also determined. Lower-vigour trees from Penta∗ rootstock grafting yielded larger fruit with improved skin overcolour, and greater total polyphenols content and antioxidant capacity. GF677 rootstock produced more vigorous trees with fruit with lower sensorial and nutritional parameters. Canopy position strongly affects fruit sensorial and nutritional qualities. These data define potential for improvements to peach production efficiency and fruit quality, particularly for southern Europe peach cultivation conditions.

Produção de mudas de tangerineira 'Ponkan' em sistema hidropônico

The production in hydroponics of grafted seedlings has been used successfully for various crops, due to its precocity and absence of pathogens, mainly from the soil and substrates. This research was therefore carried out with the aim of studying the feasibility of the production of Rangpur-lime rootstock in a hydroponic system, by determining the optimal diameter of the rootstock for grafting onto the tangerine cultivar Ponkan, and by evaluating the production of the grafted seedlings. The experiment was conducted in two stages in a greenhouse in the Hydroponics Sector of the Department of Soil Science at the Federal University of Lavras in Minas Gerais. In the first stage, the growth of Rangpur lime rootstock (Citrus limonia Osbeck) was investigated. In the second stage, the optimal diameter of the rootstock for grafting was evaluated together with the viability of the production of seedlings of the tangerine cultivar Ponkan (Citrus reticulata Blanco) when grafted onto rootstock of the Rangpur lime. Both steps were carried out in a hydroponic system, using a completely randomized experimental design. The treatments of each experiment were times of evaluation (in weeks) consisting of five replications of five seedlings, giving a total of 25 rootstocks per tube. The rootstock of Rangpur lime with a diameter of 7mm, was the most suitable for the propagation of seedlings of the tangerine cultivar Ponkan (Citrus reticulata Blanco), presenting the best vegetative growth of the graft, with a protrusion time of 91 DAE, surpassing the time for the formation of the citrus seedlings obtained from the other diameters (4, 5 and 6mm). The hydroponic system was shown to be a viable technique for propagating citrus seedlings.

Effect of grafting Nubian watermelon on its growth, flowering, yield and fruit quality.

Two field experiments were carried out on Nubian watermelon (Citrullus lanatus var.Colocynthoide) during the summer season of 2009 and 2010 in the farm of Sakha ResearchStation in Kafr El-Sheikh Governorate. The main objective of the study was comparison of nongraftedwatermelon plants with four rootstocks: bottle gourd (Lagenaria siceraria), pumpkin(Cucurbita moschata), luffa (Luffa cylindrical) and fig leaf gourd (Cucurbita ficifolia) toimprove Nubian watermelon production by using grafting technique. The study includedmeasurement of vegetative growth parameters, flowering, fruit and seed yield and fruitcharacteristics.The results indicated that grafting Nubian watermelon onto bottle gourd and pumpkin rootstockswas the best grafting compared to the control.Grafting onto bottle gourd rootstock significantly increased number of hermaphrodite flowerwhile, the lowest numbers were obtained from non-grafted plants and those grafted onto luffa.Grafting onto bottle gourd significantly increased both number of fruit/plant, seeds/ fruit andfruit weight, while non-grafting plants and grafting onto fig leaf gourd led to lowest values ofthem. Grafting onto bottle gourd followed by pumpkin significantly increased fruit yield per m2,seed yield per m2, both weights of fruit yield (ton/fed.) and seed yield (ton/fed) in comparisonwith non-grafting plants and grafting onto luffa.Plants grafting onto bottle gourd rootstock had the highest dry weight of 100 seeds, net weightof seed kernel values, the highest fruit length, fruit diameter and fruit shape values.The main objective of this investigation was chosen suitable rootstock for grafting and studyingits effect on growth and yield of Nubian watermelon plant.

Growth, gas exchange, and water-use efficiency response of two young apple cultivars to drought stress in two scion-one rootstock grafting system

The combination of two scion-one rootstock was used for two apple cultivars, ‘Pink Lady’ and ‘Qinguan’, budded on the same, one-year-old Malus hupehensis (Pamp.) Rehd. to reduce the impact of root and pot size and in order to understand the growth, water-use efficiency (WUE), and chlorophyll fluorescence characteristics. The two-scion grafted trees were planted in plastic pots under two water regimes, i.e. 70% field capacity (FC) and 55% FC. Results indicated that different scions were affected differently by drought stress. ‘Pink Lady’ had higher net photosynthetic rate (PN), stomatal conductance (gs), and transpiration rate (E) compared with ‘Qinguan’ under both water treatments. However, ‘Qinguan’ had lower minimal fluorescence (F0), higher maximum fluorescence (Fm), and higher maximum photochemical efficiency of photosystem II (Fv/Fm) than ‘Pink Lady’ at 55% FC. Moreover, ‘Qinguan’ had larger shoot dry mass (ShDM) and higher intrinsic WUEI than ‘Pink Lady’ under both water status. Gas-exchange and growth parameters, except for PN and scion diameter, were significantly affected by the cultivar and water treatment. At 70% FC, ShDM was significantly correlated with WUEI. Moreover, WUEI was negatively linearly correlated with gs at either 70 or 55% FC. These results might indicate that ‘Pink Lady’ was more sensitive to drought than ‘Qinguan’. ‘Qinguan’ apple was able to improve WUE more than ‘Pink Lady’ under both well-watered and drought conditions. The growth parameters and photosynthetic capacity of two different scions showed that the combination of double scion-one rootstock might eliminate the influences of the rootstock and pot size.

Increased cucumber salt tolerance by grafting on pumpkin rootstock and after application of calcium

Self-grafted and pumpkin rootstock-grafted cucumber plants were subjected to the following four treatments: 1) aerated nutrient solution alone (control), 2) nutrient solution with 10 mM Ca(NO3)2 (Ca), 3) nutrient solution with 90 mM NaCl (NaCl), and 4) nutrient solution with 90 mM NaCl + 10 mM Ca(NO3)2 (NaCl+Ca). The NaCl treatment decreased the plant dry mass and content of Ca2+ and K+ but increased the Na+ content in roots and shoots. Smaller changes were observed in pumpkin rootstock-grafted plants. Supplementary Ca(NO3)2 ameliorated the negative effects of NaCl on plant dry mass, relative growth rate (RGR), as well as Ca2+, K+, and Na+ content especially for pumpkin rootstock-grafted plants. Supplementary Ca(NO3)2 distinctly stimulated the plasma membrane (PM) H+-ATPase activity which supplies the energy to remove excess Na+ from the cells. The expressions of gene encoding PM H+-ATPases (PMA) and gene encoding a PM Na+/H+ antiporter (SOS1) were up-regulated when Ca(NO3)2 was applied. The pumpkin rootstock-grafted plants had higher PM H+-ATPase activity as well as higher PMA and SOS1 expressions than the self-grafted plants under NaCl + Ca treatment. Therefore, the addition of Ca2+ in combination with pumpkin rootstock grafting is a powerful way to increase cucumber salt tolerance.

Solanum torvum as a Compatible Rootstock in Interspecific Tomato Grafting

Two tomato scions (‘Celebrity’ and ‘CLN3212A’) were grafted onto Solanum torvum and tomato ‘Maxifort’ rootstock to determine compatibility. Experimental design included self-grafted and non-grafted control rootstocks. Seed vs. vegetative S. torvum rootstocks were also compared to further explore grafting options. Average number of days for graft fusion and survival rate was measured for each scion/rootstock combination. Vegetative S. torvum cuttings had the poorest grafting success rate as a rootstock (50% for both scions), while all other rootstock genotypes had statistically similar or higher success rates. There was no significant difference in time to graft fusion among any grafted genotypes. High compatibility of seed-derived S. torvum suggests its potential use as an interspecific grafting rootstock in areas where access to seed is readily available.

APPLICATIONS OF FAR-RED LIGHT EMITTING DIODES IN PLANT PRODUCTION UNDER CONTROLLED ENVIRONMENTS

ISHS International Symposium on Advanced Technologies and Management Towards Sustainable Greenhouse Ecosystems: Greensys2011 APPLICATIONS OF FAR-RED LIGHT EMITTING DIODES IN PLANT PRODUCTION UNDER CONTROLLED ENVIRONMENTS

Seedling resistance to Phytophthora cinnamomi in the genus Abies

Root rot and stem canker caused by Oomycete species belonging to the genus Phytophthora often seriously limit culture of true firs (Abies spp.) An investigation of the variation of resistance among Abies species to Phytophthor a cinnamomi was carried out to identify potential sources of resistance in the genus. Thirty-two Abies species were grown in a greenhouse for 2 and/or 3 years from seed. Seedlings were moved to an outdoor lath house, inoculated with rice grains colonized with P. cinnamomi, and subsequent mortality was assessed biweekly for 16 weeks. Disease developed rapidly resulting in 88.1 % overall mortality 16 weeks after inoculation. Mortality was less in two of the eight taxonomic sections of the genus evaluated, Momi (0.65 ± 0.0252) and Abies (0.79 ± 0.0193). Mortality in all other sections exceeded 93 %. Final species mortality ranged from 10.6 % (Abies firma) to 100.0 % (several species). Although several caveats apply, results have identified potential sources of Abies to be used as (1) resistant planting stock, (2) grafting rootstock, and (3) parents in hybridization/backcrossing programs in order to mitigate losses caused by P. cinnamomi.

Evaluation of Grafting Using Hybrid Rootstocks for Management of Bacterial Wilt in Field Tomato Production

Seven hybrid tomato rootstocks with possible resistance to bacterial wilt caused by Ralstonia solanacearum and a known resistant cultivar were tested as grafting rootstocks to impart resistance to a bacterial wilt-susceptible cultivar, BHN 602. Greenhouse studies showed resistance of all the rootstocks to bacterial wilt. The disease incidence and yield of ‘BHN 602’ grafted to these rootstocks were evaluated in open-field tomato production in Florida and Virginia over four seasons. Significant differences in bacterial wilt incidence were observed between grafted entries in three of the four trials. In these three trials, grafted entries consistently exhibited the least bacterial wilt incidence compared with the controls; the self-graft, and non-grafted entries. Over all the trials, tomato plants grafted onto ‘Cheong Gang’, ‘BHN 1054’, and ‘BHN 998’ displayed the least bacterial wilt incidence. Rootstocks had a significant effect on total marketable yield in all the trials with certain grafted entries yielding significantly greater than non-grafted ‘BHN 602’. Field studies show that grafting holds promise for decreasing the impact of bacterial wilt on tomato cultivars as well as increasing the overall productivity of tomato cultivars.

Influence of rootstock on antioxidant system in leaves and roots of young apple trees in response to drought stress

Grafting rootstocks are widely used to enhance plants resistance to various biologic and abiotic stresses. We determined how the rootstock genotype might influence plant responses to drought, using 2-year-old ‘Gale Gala’ apple trees grafted onto Malus sieversii and M. hupehensis. Under water stress, trees with the former as their rootstock had smaller reductions in rates of relative growth and photosynthesis, total biomass, leaf area, levels of leaf chlorophyll, and relative water content compared with those grafted onto the latter. They also had greater maximum photochemical efficiency and water-use efficiency. On the other hand, trees growing on M. sieversii rootstock had less production of superoxide radicals and hydrogen peroxide in both leaves and roots than those growing on M. hupehensis in response to drought stress. Furthermore, under drought conditions, leaves and roots from trees grafted onto M. sieversii had greater synthesis of ascorbic acid and glutathione, as well as higher activities of superoxide dismutase, catalase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase. These results suggest that the choice of grafting rootstock can enhance drought resistance by improving the antioxidant system in a plant. Here, ‘Gale Gala’ trees grafted onto M. sieversii were more drought-resistant than those on M. hupehensis rootstock.

Effects of salt-tolerant rootstock grafting on ultrastructure, photosynthetic capacity, and H2O2-scavenging system in chloroplasts of cucumber seedlings under NaCl stress

Plant growth, photosynthetic parameters, chloroplast ultrastructure, and the ascorbate-glutathione cycle system in chloroplasts of self-grafted and rootstock-grafted cucumber leaves were investigated. Grafted plants were grown hydroponically and were exposed to 0, 50, and 100 mM NaCl concentrations for 10 days. Under NaCl stress, the hydrogen peroxide (H2O2) content in cucumber chloroplasts increased, the chloroplast ultrastructure was damaged, and the gas stomatal conductance, intercellular CO2 concentration, as well as shoot dry weight, plant height, stem diameter, leaf area, and leaf relative water content were inhibited, whereas these changes were less severe in rootstock-grafted plants. The activities of ascorbate peroxidase (APX; EC 1.11.1.11), glutathione reductase (GR; EC 1.6.4.2), and dehydroascorbate reductase (DHAR EC 1.8.5.1) were higher in the chloroplasts of rootstock-grafted plants compared with those of self-grafted plants under 50 and 100 mM NaCl. Similar trends were shown in leaf net CO2 assimilation rate and transpiration rate, as well as reduced glutathione content under 100 mM NaCl. Results suggest that rootstock grafting enhances the H2O2-scavenging capacity of the ascorbate–glutathione cycle in cucumber chloroplasts under NaCl stress, thereby protecting the chloroplast structure and improving the photosynthetic performance of cucumber leaves. As a result, cucumber growth is promoted.

PHOTOSYNTHETIC ABILITY AND MINERAL CONCENTRATIONS IN XYLEM EXUDATE OF GRAFTED AND NON-GRAFTED WATERMELON SEEDLINGS

Grafting as an effective method to overcome soilborne pathogens is widely performed in watermelon (Citrullus Lanatus Mansfeld) production in China. To evaluate physiological characteristics of the grafted plants, taking watermelon 'Jingxin 1' as the scion and Cucurbita ficifolia as rootstock for grafting, growth, photosynthetic ability and mineral concentrations in xylem exudate were investigated in comparison of non-grafted and grafted watermelon seedlings. The results showed the grafted seedlings grew faster. In the grafted seedlings, the plant height, number of leaves, the area of the largest leave, shoot dry weight, root dry weight and ratio of R/T were significantly higher than those of non-grafted seedlings. Chlorophyll content, stomatal conductance (Gs), intercellular CO 2 concentration (Ci) and net photosynthetic rate (Pn) were also significantly higher in grafted seedlings leaves. The grafted seedlings yielded much more xylem exudate. The concentration of NO 3 - -N in the exudates of grafted seedlings was about 2 times of the non-grafted seedlings. NO 3 - -N was the main form of nitrogen in both grafted and non-grafted seedlings xylem exudates. Concentrations of P, Ca and Mg were also higher but K was lower in the exudate of grafted seedlings. These results indicated that the grafted seedlings had higher photosynthetic ability and higher root absorption capacity for NO 3 - -N, P, Ca and Mg, but lower absorption capacity for K.

EFFECTS ON CARBOHYDRATE AND AMINO ACIDS ACCUMULATION IN MUSKMELON FRUIT (CUCUMIS MELO L.) WITH DIFFERENT GRAFTING ROOTSTOCKS

Effects on the carbohydrate and amino acids accumulation in the muskmelon fruits as substrate tub plants in solar greenhouse with different scion (Cucumis melo L. 'Zhongmi 1')/rootstock (Cucurbita maxima ×moschata) grafting combinations are under study. The results indicate that G1 ('Zhongmi 1'/'Riben Strong') and G3 ('Zhongmi 1'/'Shengzhen 1') increased yield by 16.78 and 20.8% on 42 DAA (days after anthesis) and by 18.51 and 26.29% on 50 DAA respectively. G3 reduced sugar accumulation, activity in the synthesis direction of sucrose synthase and sucrose phosphate synthase activity but increased invertase activity significantly during 34 to 50 DAA. On the contrary, G1 increased sugar content with the increase of sucrose phosphate synthase activity on 50 DAA, which indicated that grafting influenced sugar accumulation by changing sucrose metabolic enzyme activities. On the other hand, G1 increased significantly the contents of threonine, glutamic acid, methionine, isoleucine and lysine in muskmelon mesocarp, but decreased the contents of alanine, cysteine and histidine. G2 ('Zhongmi 1'/'Quanwang') dramatically enhanced the contents of threonine, methionine, tyrosine and lysine in muskmelon mesocarp, but lowered the contents of alanine, cysteine and histidine. G3 significantly increased the contents of threonine, serine, glutamic acid, glycine, methionine, phenylalanine, arginine, isoleucine, leucine, tyrosine, lysine and histidine in muskmelon mesocarp, but decreased the contents of alanine and cysteine. On the whole, grafting changed the contents of all amino acids except valine, influencing the fruit flavors. In conclusion, 'Zhongmi 1'/'Riben Strong' grafting combination was more appropriate for high fruit quality as followed by 'Zhongmi 1'/'Shengzhen 1' and 'Zhongmi 1'/'Quanwang' graft combinations.

Grafting as a tool in common bean breeding

Compatibility of rootstock for grafting was investigated in four species of Phaseolus to study the use of grafting as a tool in bean breeding programs. Four genotypes of Phaseolus vulgaris and one genotype of P. coccineus were used as rootstocks. Two genotypes of P. vulgaris, and one each of P. acutifolius and P. angustissimus, and an interspecific hybrid of P. acutifolius × P. angustissiumus were used as scions. The common bean genotype ICA Pijao, a widely used female parent in bean interspecific hybridization, was the most compatible rootstock among the five genotypes tested, with high mean percent survival for scions across all four Phaseolus species. Grafting was an efficient technique compared with rooted cuttings for seed increase in determinate type bean plants, where obtaining the maximum number of clones before the reproductive phase is critical. Grafting resulted in 91 and 66% higher mean seed yield per plant compared with ungrafted control and rooted cutting treatments, respectively. This grafting technique using compatible rootstocks such as P. vulgaris ICA Pijao has potential to improve early generation seed increase ratio, multiplication of clones for screening, and perpetuation of sterile or recalcitrant interspecific hybrids for various breeding strategies. Key words: Grafting, Phaseolus sp., interspecific hybrids, compatible rootstocks, clonal propagation, seed multiplication, breeding efficiency

Crescimento vegetativo de porta-enxertos de citros produzidos em substratos comerciais

Este trabalho teve o objetivo de avaliar o crescimento vegetativo de porta-enxertos de citros produzidos em diferentes substratos comerciais, mantidos em recipientes de quatro litros. O experimento foi desenvolvido em casa de vegetação, na Estação Experimental Agronômica da UFRGS, em Eldorado do Sul, RS, no período de junho/2003 a março/2004, e seguiu o delineamento experimental de blocos casualizados, testando-se três substratos comerciais: Turfa preta (Comercial 1); cascas processadas e enriquecidas, vermiculita expandida, perlita expandida e turfa (Comercial 2); e casca de pínus compostada e vermiculita (Comercial 3) e três porta-enxertos: ("Trifoliata"; citrangeiro "C13" e limoeiro "Cravo"). A irrigação foi feita por gotejamento. Avaliaram-se as seguintes variáveis: diâmetro do colo; altura da parte aérea; número de folhas e área foliar; matéria seca das raízes, da parte aérea e total; conteúdo de nutrientes nas folhas e percentual de porta-enxertos aptos à enxertia. A interpretação dos resultados revelou que o substrato com cascas processadas e enriquecidas, vermiculita expandida, perlita expandida e turfa possibilitou maior desenvolvimento vegetativo aos porta-enxertos utilizados, devido ao maior aporte de nutrientes. Os porta-enxertos mostraram desenvolvimento diferenciado, sendo que o citrangeiro "C13" tem potencial de uso para a diversificação de porta-enxertos na citricultura, devido ao seu desenvolvimento vegetativo.

Determination of genetic stability of grafted marula trees using AFLP markers

Genetic stability of grafted marula trees within seven lines, some of which exhibiting interline phenotypic variations, was evaluated using the AFLP technique. The study was conducted in two-fold using samples from the DR, LP, MR, OS, PH, SW and TR lines. The genetic analysis using leaf materials indicated varying levels of genetic variations between genotypes within the OS, MR, LP and PH lines. The genotypes of the DR, TR and SW lines showed high intraspecific genetic similarity and formed tight clusters on the UPGMA-based dendrogram. The genetic analysis using a subset of the initial sample set constituting both leaf and bark materials which represented the scion and the rootstock components of grafted trees showed high genetic similarities between the graft partners of some genotypes within the OS and PH lines. These high levels of genetic similarity between scion and rootstock partners of a grafted tree suggested that the rootstock graft developed shoots and grew into a tree following graft failure. The observed results imply that grafting is not always successful even within compatible species, however, it can be reliably monitored using molecular markers.

IN VITRO GERMINATION OF THREE OLIVE CULTIVARS

Olive seedlings are used in breeding programs as well as rootstocks for grafting of hard-to-root cultivars. However, olive seed germination is not easy, low and slow germination rate are some of the persisted problems. In vitro germination of isolated embryos could be a useful method for increasing the efficiency of germination. One of the main following objectives in embryo culture is the isolation of embryo from the endosperm that contains inhibitory germination substances. This results to shortening of reproductive cycle and the necessary time for obtaining seedlings. In this study, the embryo germination potential of three olive cultivars including 'Manzanilla' and two Iranian cultivars i.e. 'Dezful' and 'Zard' was evaluated. Also the effect of three harvesting times (middle of August, September and October) on growth and development of embryos was studied. Aseptically isolated embryos were cultured in MS medium with one third of macro elements and placed in growth chamber at 25°C day, 21°C night with 16-h photoperiod. According to results, some differences were revealed between germination percent of embryos and the following growth of them. The highest germination percent and seedling formation was obtained at the first culture time with means of 86 and 73 percent, respectively. 'Dezful' cultivar with 90% germination and 79% seedling formation showed the highest values.

EFFECT OF SOME CHEMICAL MATERIAL AND GERMINATION MEDIA ON SEED GERMINATION AND GROWTH OF GRAFTED CASIMIROA TRANSPLANTS

This investigation was carried out in the plastic house of Horticulture Research Institute, Agriculture Research Center, Giza during two consequent seasons (2002 – 2003) and (2003 – 2004). The study was aimed to enhance growth of Casimiroa rootstock seedlings to reach grafting size in a short time, beside defineding the suitable method of grafting. In this concern, results revealed that seed soaked in MgSO4 at 5 % for 15 min. and planted in media consists of peat and sand at 1 : 1, was increased seed germination percentage (92.1 and 94.8 %) and minimized the germination period (19.1 and 19.3 days), as compared with the other treatments. Thus it reached to the grafting size at a period of (179 and 180 days) in both seasons, respectively. However, Dormex (hydrogen cyanamide) treatment at 2% gave the highest root length (24.6 and 24.8 cm), and number of roots per plant (19.4 and 19.0). Results also showed that shield budding by using soft wood grafts, gave the highest percentage of success (69.2 and 72.4%), shortest period of bud / scion (23.0 and 24.0 days), highest values of scion length (26.5 and 25.7 cm) and highest leaf area (38.28 and 40.67 cm2). However, cleft grafting with softwood grafts increased average number of leaves per sprouted graft (6.0 and 6.6) and shoot scion diameter (0.6 and 0.5 cm). Generally, seeds treated with MgSO4 at 5% berfore sowing in media consists of peat and sand at 1 : 1 in volume, induced healthy and sizeable rootstocks in a short time. Moreover, grafting rootstocks by soft wood grafts was the best method.