Achieving a uniform stand of grafted vegetable transplants in the field is critical to the grower because of the high cost of the grafted transplants. Low and erratic stands can lead to monetary losses even in an otherwise successful crop. Establishing a uniform stand of grafted vegetable transplants in the field depends on several additive parameters prevailing in the nursery and in the field. These include seed quality, grafted-transplant quality, and agrotechniques suitable for the special needs of grafted transplants. Seed quality and seed health should be given special emphasis as compared with non-grafted-transplant production. Grafted transplants spend more time in the nursery, are treated manually more, and are more susceptible to seed-borne pathogens. Field preparation, plastic mulch, irrigation and fertilization are important, especially in warm, mediterranean climates.
Amnon Koren* and Menahem Edelstein
Amnon Koren* and Menahem Edelstein
Grafting technology for vegetable transplants was introduced to Israel eight years ago by Hishtil Nurseries, Inc. The main goal of grafting was to find a substitute for methyl bromide, the elimination of which was pending. The use of grafted watermelon transplants soon followed. Presently, more than 40% of watermelon transplants are grafted. The chief reason for the success of grafted transplants is their tolerance to soil-borne pathogens, including Fusarium, Monosporascus, and Macrophomina. Yields of grafted transplants are often much higher, and it has been shown possible to grow watermelons with saline water (4.5). A limitation of grafted transplants is that presently, we do not have a good solution for nematodes. A drawback is that in order to get good watermelon taste and flavour, the grower needs the experience to adjust agrotechniques, especially determining the best harvest date. Grafted tomato transplants were also introduced early on. Grafted tomato transplants can have excellent resistance to fusarium crown rot, corky root, and other soil-borne pathogens. Some rootstocks have been observed to tolerate water salinity of 8 ec and still produce commercially acceptable yields. Limitations to the use of grafted tomato transplants are the lack of compatibility of some of the cultivars with the rootstocks and the breakdown of nematode resistance at high soil temperatures. Melons, eggplants, and cucumbers are grafted under some conditions.
Menahem Edelstein and Haim Nerson
Germination percentage and germination rate were examined in two melon accessions differing in their ability to germinate under low temperature and in their reciprocal F1, F2, and BC1 progeny. The seedcoat structure, pressure force required for seedcoat splitting, and the response to hilum sealing of the reciprocal F1s were examined as well. The purpose of this study was to elucidate the effects of embryonic genotype and seedcoat characteristics on the ability of melon seeds to germinate under low temperature. The results of the study point out that both components are strongly involved in low-temperature germination. The cold tolerant parent, ‘Persia 202’ (P202), germinated greater than 90% at 15 °C, whereas the cold-sensitive parent, ‘Noy Yizre'el’ (NY), did not germinate at all. The P202 × NY F1 and the reciprocal F2 germinated 80% to 90%, whereas the NY × P202 F1 germination percentage was only 71%. Backcrosses of the reciprocal F1 to the parents revealed that if the cross was to the tolerant one, the seeds germinated greater than 90%, but if the F1s were backcrossed to the sensitive parent, the seeds had only 56% to 60% germination. Data collected suggest that several dominant genes are carried by P202 for low-temperature germination. On the other hand, the difference in germination percentages between the reciprocal F1 demonstrates that the different seedcoats also play a role.
Menahem Edelstein and Haim Nerson
The effects of plant spacing (5,000-40,000 plants per hectare) on watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] production for seed consumption were evaluated in two breeding lines, 203 and 239-4, and in the standard cultivar Malali in three field experiments in northern Israel. The two breeding lines produced more, but smaller fruits than did `Malali', resulting in nearly double the seed yield per unit area. Seed size was not affected by fruit size, unless fruit size was <500 g. The total number of fruits per unit area was the most important component in determining seed yield. Increasing the plant population increased the seed yield in all three accessions. Breeding and agricultural practices that maximize fruit number per unit area are expected to be most beneficial in maximizing the yield of watermelon grown for seed consumption.
Roni Cohen*, Yosef Burger, and Menahem Edelstein
The use of grafted vegetables as one of the alternatives to soil disinfestation with methyl bromide is increasing in Israel. Watermelon (Citrullus lanatus) and melon (Cucumis melo) plants are grafted mainly onto Cucurbita rootstocks for lessening losses due to soil-borne pathogens. The contribution of the rootstock to the grafted plant's resistance depends on the nature of the disease. In general, damage caused by non-specific root-rot pathogens such as Rhizoctonia solani, Macrophomina phaseolina, Monosporascus cannonballus, and Pythium spp. are effectively reduced by using Cucurbita rootstocks. However, these rootstocks provide only partial protection from vascular diseases such as fusarium wilt, in which case better protection can be achieved by grafting susceptible melons onto monogenic fusarium-resistant melon rootstocks. The performance of the grafted plants depends not only on the rootstock but also on the scion response to pathogens and on the effect of the environment on disease development. The response of grafted and non-grafted melons of different cultivars to sudden wilt disease caused by the fungus Monosporascus cannonballus was evaluated in field trials conducted in the fall and spring growing seasons. Significant differences in disease incidence were found among cultivars, between grafted and non-grafted plants, and between seasons. Grafting reduced plant mortality in the spring and fall experiments but prevention of yield losses was more effective in the spring. More emphasis should be given to finding suitable rootstocks and adjusting agrotechniques for successful commercial cultivation of grafted melons in the fall.
Menahem Edelstein, Meni Ben-Hur, and Zui Plaut
The effects of boron and effluent (treated sewage water) on vegetative growth, fruit yield, and boron uptake of grafted and nongrafted melons (Cucumis melo L. cv. Arava) were studied. Nongrafted melon plants and melon plants grafted onto the commercial Cucurbita maxima Duchesne × Cucurbita moschata Duchesne rootstock ‘TZ-148’ were grown in pots filled with perlite in a heated greenhouse and were irrigated with fresh water or effluent. The two irrigation waters contained boron in five concentrations ranging from 0.1 to 10.4 mg·L−1. The boron concentration in the plants increased linearly with that in the irrigation water. The highest boron concentrations were found in old leaves, the lowest in the fruit, and intermediate concentrations were noted in the roots. The boron concentrations were, in general, significantly lower in grafted than nongrafted plants, possibly because the root system of the former had higher selectivity and lower boron absorption than that of the latter. Fruit yield and dry weight accumulation in shoots and roots decreased linearly as the boron concentration in the irrigation water increased, the nongrafted plants were more sensitive than grafted ones to the boron level, and both were more sensitive under fresh water irrigation than under effluent irrigation. It is suggested that the higher boron sensitivity of the root systems of the nongrafted plants probably decreased their capability to absorb water and nutrients, which in turn sharply reduced their fruit yields.
Hira Singh, Pradeep Kumar, Sushila Chaudhari, and Menahem Edelstein
Grafting of vegetable seedlings is a unique horticultural technology practiced for many years in East Asia to overcome issues associated with intensive cultivation using limited arable land. This technology was introduced to Europe and other countries in the late 20th century along with improved grafting methods suitable for commercial production of grafted vegetable seedlings. Tomato grafting is becoming a well-developed practice worldwide with many horticultural advantages. The primary motivation for grafting tomato has been to prevent the damage caused by soilborne pathogens under intensive production system. However, recent reports suggest that grafting onto suitable rootstocks can also alleviate the adverse effects of abiotic stresses such as salinity, water, temperature, and heavy metals besides enhancing the efficiency of water and nutrient use of tomato plants. This review gives an overview of the scientific literatures on the various aspects of tomato grafting including important steps of grafting, grafting methods, scion–rootstock interaction, and rootstock-derived changes in vegetative growth, fruit yield, and quality in grafted plants under different growing conditions. This review also highlights the economic significance of grafted tomato cultivation and offers discussion on the future thrust and technical issues that need to be addressed for the effective adoption of grafting.
Pradeep Kumar, Menahem Edelstein, Mariateresa Cardarelli, Emanuela Ferri, and Giuseppe Colla
A greenhouse experiment was conducted to determine the influence of long-term cadmium (Cd) exposure (0, 25, or 50 µm of Cd) on crop productivity, fruit quality, leaf chlorophyll content, fluorescence, and mineral composition in plants of tomato (Solanum lycopersicum L. cv. Ikram), either nongrafted, self-grafted, or grafted onto rootstocks of tomato (Maxifort or Unifort) and eggplant (Black Beauty). Both moderate (25 µm) and high (50 µm) concentration of Cd in root environment considerably decreased the fruit yield and fruit number in response to Cd levels, whereas mean fruit weight decreased but was similar to both Cd supply levels. The fruit yield, shoot and root biomass, and leaf area (LA) were higher in plants grafted onto tomato rootstocks and especially onto Maxifort in comparison with nongrafted or self-grafted plants and especially grafted onto Black Beauty. The higher plant performance of tomato rootstock–grafted plants were related to higher chlorophyll fluorescence and photosynthetic pigments concentration in leaves associated with better nutrient translocation and availability (higher Ca, Mg, Fe, Mn, and Cu) in leaves. The content of Cd was also lower in leaves and fruits of Maxifort-grafted plants. Concerning fruit quality, especially peel color, toxicity symptoms, and Cd concentration, Black Beauty followed by Maxifort-grafted plants were better than the other grafting combinations. However, plants grafted onto Black Beauty rootstock resulted in lowest fruit yield and plant growth attributes due to lower nutrient uptake and translocation indicating some incompatibility reaction between Black Beauty rootstock and Ikram scion.
Menahem Edelstein*, Meni Ben-Hur, Ron Cohen, Yosef Burger, and Israela Ravina
Excess of boron and salinity in soil and irrigation water can limit the production of melons (Cucumis melo). A greenhouse study was conducted in order to compare the responses of grafted and non-grafted melon plants to combinations of high levels of boron and salinity. Boron levels were 0.25, 0.8, 2.5, 5.0, 10.0 mg·L-1 and salinity levels were 1.8 and 4.6 dS·m-1. Foliar injury caused by boron was more severe in the non-grafted than in the grafted plants. Likewise, boron accumulation in leaf tissue from non-grafted plants was higher than in grafted plants. High salinity led to decreased boron accumulation in the leaves. Fruit yield was decreased only at a boron concentration of 10 mg·L-1, and the decrease in grafted plants was smaller than that in non-grafted plants. A negative correlation was found between boron accumulation in leaves and fruit yield. The results showed that melon plants grafted on Cucurbita rootstock are more tolerant than non-grafted ones to high boron concentrations, and this can probably be explained by the decrease in boron accumulation caused by the rootstock.
Menahem Edelstein, Roni Cohen, Meital Elkabetz, Shimon Pivonia, Ami Maduel, Tom Sadeh-Yarok, and M. Ben-Hur
Melon plants grafted on Cucurbita rootstock may suffer from nutritional deficiencies due to reduced absorption and translocation of minerals to the foliage. Melon (Cucumis melo L.) cv. 6023 was grafted onto two interspecific Cucurbita rootstocks (Cucurbita maxima × Cucurbita moschata) ‘TZ-148’ and ‘Gad’. Nongrafted melons were used as controls. Two fertilization field experiments were conducted in walk-in tunnels in the northern Arava valley of southern Israel. Two fertigation regimes were used: 1) standard and 2) enriched for magnesium (Mg; 150 mg·L−1), manganese (Mn; 7.5 mg·L−1), and zinc (Zn; 0.75 mg·L−1) to increase the concentrations of the lacking elements. The enriched fertigation significantly increased Mn, Zn, and Mg contents in the leaf tissue. Concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), chloride (Cl), iron (Fe), and boron (B) were unaffected by the enriched fertilizer. There were no deficiency symptoms in grafted plants supplied with the enriched fertilizer.