<b>The influence of rootstock and time of harvest on the fruit quality during storage of in two grapefruit cultivars

Abstract

ABSTRACT. The effects of the 'Cleopatra' mandarin and 'Swingle' citrumelo rootstocks and time of harvest on the quality of cold-stored (13°C and 90% R.H.) 'Ruby Red' and 'Star Ruby' grapefruit grown under the tropical conditions prevalent in Ceará state, Brazil, were evaluated. Fruit quality was assessed by mass loss and peel color, the percentage of juice, soluble solids, titratable acidity, pH, maturity index, and ascorbic acid content. The results suggested that 'Ruby Red' and 'Star Ruby' grapefruit presented similar amounts of soluble solids, pH, titratable acidity and ascorbic acid levels at harvest, and the trends over the course of storage followed similar patterns for both cultivars, regardless of rootstock. The influence of scion-rootstock combination on the studied variables was dependent on the time of harvest. The peel color of 'Ruby Red' grafted on 'Swingle' citrumelo is more vivid and redder when harvested in October than when harvested in August. 'Ruby Red' and 'Star Ruby' grapefruit harvested in October are sweeter, less acidic, juicier, and richer in ascorbic acid than those harvested in August. 'Cleopatra' mandarin rootstock might favor ascorbic acid levels at harvest, but the fruit may lose more weight during storage.Keywords: Citrus paradisi Macf., postharvest, semi-arid conditions.Influencia do porta-enxerto e época de colheita na qualidade do fruto durante o armazenamento de duas cultivares de pomelos RESUMO. Experimentos foram conduzidos objetivando verificar a influência dos porta-enxertos tangerina 'Cleopatra' e citrumeleiro 'Swingle', e época de colheita na qualidade dos pomelos 'Ruby Red' e 'Star Ruby' cultivados sob as condições semiáridas do Estado do Ceará e armazenados sob refrigeração (13°C e 90% U.R.). A qualidade dos frutos foi avaliada através das medições de perda de massa, coloração da casca, percentagem do suco, sólidos solúveis, acidez titulável, pH, índice de maturação e teores de ácido ascórbico. Os resultados sugerem que os pomelos 'Ruby Red' e 'Star Ruby' apresentam teores similares de sólidos solúveis, pH, acidez titulável e ácido ascórbico á colheita, enquanto as variações durante o armazenamento seguiram tendências semelhantes para ambos os cultivares, independente do porta-enxerto. Influências das combinações copa e porta-enxerto, à colheita, sobre as variáveis estudadas são dependentes da época de colheita. Frutos de 'Ruby Red' sobre citrumeleiro 'Swingle' colhidos em outubro são mais vermelhos e vívidos. 'Ruby Red' e 'Star Ruby' colhidos em outubro são mais doces, menos ácidos, suculentos e mais ricos em ácido ascórbico do que os colhidos em agosto. O porta-enxerto tangerina 'Cleopatra' pode favorecer o teor de ácido ascórbico à colheita, mas os frutos podem perder mais peso durante o armazenamento.Palavras-chave: Citrus paradisi Macf., pós-colheita, condições semi-áridas.

Polyploid rootstocks in citrus for mitigation of biotic and abiotic stresses: A review

“…Hybrid origin of genotypes can favor the polyploidization (Machado et al 2015;Guerra et al 2016). As reported by Carvalho & Silva (2013), Citrumelo expressed the highest per cent of polyembryony (18.8%), followed by Rangpur lime and Volkamer lemon (13.7%), Sunki mandarin (9.4%) and Trifoliate orange (3.2%).…”

“…The plants grafted on Cleopatra rootstocks (2x) were demonstrated higher tolerance to salt and drought, and it is a well-known chloride excluder (Cerda et al 1979); however, it is susceptible to nematodes (Chadha & Singh 1990). Fruit shows low levels of albedo breakdown (Treeby et al 1995) and low susceptibility to decay under storage (Ritenour et al 2004), but it shows high levels of weight loss during storage period (Alirezanezhad & Eamin 2006;Machado et al 2015). This rootstock is very much suitable for virgin soils (Hardy, 2004).…”

Effect of Rootstock on the Fruit Quality of Mandarins "Clemenules" and "Tango", and Blood Oranges "Tarocco Rosso" and "Moro"

“…Many studies have addressed the effect of rootstock on citrus fruit color. Machado, Costa, Teixeira & Costa (2015) found that rootstock impacted color development in 'Ruby Red' grapefruit. Indeed, while Cleopatra fruit developed a yellowish external color, Citrumelo fruit displayed a pinkish peel color.…”

“…In the present study the external color was influenced by both harvest and rootstock and the interaction between these two factors was significant (Table 2). (Machado et al, 2015). Firmness is an important fruit quality parameter, but is not included in the current citrus quality standards.…”

“…Rootstocks are frequently used in citriculture to improve crop adaptation to different biotic and abiotic conditions by regulating the uptake and movement of water and nutrients among plant organs . The rootstock can also influence fruit quality parameters (Castle, 1996) such as color (Machado, Costa, Teixeira & Costa, 2015;Legua, Martinez-Cuenca, Bellver, Forner-Giner, 2018) or maturity index (McCollum, Bowman & Castle, 2002; and nutritional juice parameters, such as individual sugars and organic acids (Legua, Forner, Hernández & Forner-Giner, 2013;, phenolic compounds or vitamin C (Magwaza, Mditshwa, Tesfay & Opara, 2017). The effects of rootstock strongly depend on the rootstock-scion interaction.…”