Storage of 'Swingle' citrumelo seeds in different maturation stages subjected to fungicide treatment

Abstract

-The establishment of citrus orchards with rootstocks from seed with a low physiological quality has been a recurring problem. Low quality seeds directly affect both the final stand and the time required for seedling production. The irregular maturation of fruits, seed recalcitrance, and the high incidence of fungi, make long term storage difficult, even at low temperatures. This study evaluated the storage potential and the use of fungicide treatments on 'Swingle' citrumelo seeds extracted from fruits collected at two maturation stages, green or ripe. The seeds were subjected to a thermal treatment, treated with Derosal, Thiram or Tecto+Captan fungicides, packaged in impermeable polyethylene bags and stored in a cold chamber for nine months. Every three months, the physiological and sanitary qualities of the seeds were evaluated from germination and sanitary tests and also from enzyme profiles. Seeds from green fruits deteriorated less than those from mature fruits; deterioration increased up to nine months of storage; treatment with the Tecto+Captan mixture gave effective pathogen control and maintained seed quality during storage. The germination of the green and ripe seeds is satisfactory (70%) after three months storage. deterioram-se menos que as de frutos maduros, sendo a deterioração crescente até nove meses de armazenamento; o uso da mistura Tecto+Captan é eficiente no controle de patógenos e mantém a qualidade das sementes e ao três meses de armazenamento a germinação das sementes verdes e maduras é satisfatória (70%).Termos para indexação: citrumelo'Swingle', fisiologia, sanidade de sementes, conservação.

Swingle citrumelo seed vigor and storability associated with fruit maturity classes based on RGB parameters

“…Although similar in germination, seeds extracted from G fruits showed significantly lower vigor compared with Y fruits at 0-month storage. Silva et al (2011) reported higher seed germination from ripe (yellow) fruits compared with unripe (green) fruits just after harvest. In the wild, Citrus garrawayi F. M. Bailey, seeds with incomplete embryo and seed tissue differentiation (extracted from unripe fruit coats) produced only 4 % normal seedlings, in contrast to 88 % in ripe fruits (Hamilton et al, 2007).…”

“…According to Silva et al (2011), this water content is ideal to maintain high viability of Swingle citrumelo seeds. In contrast, von Pinho et al (2005) reported that Swingle citrumelo seeds should be stored at 44 % water content in a cold room (10 °C and 50 % RH) in impermeable bags due to its recalcitrant behavior.…”

“…In Brazil, Swingle citrumelo is one of the preferred rootstocks due to its tolerance to citrus sudden death, a severe disease found in the late 1990s in the Southwest of Minas Gerais State and the North of São Paulo State (Gimenes-Fernandes and Bassanezi, 2003). However, nurseries have faced problems in the production of seedling rootstocks such as poor germination and low seed storage potential (Carvalho et al, 2002;Roberts, 1973;Rodrigues et al, 2010), as well as difficulties to identify the optimum fruit ripening stage to obtain high quality seeds (Medina et al, 2005;Silva et al, 2011).…”

“…The fruit ripening stage at harvest is one of the major factors affecting citrus seed storage potential (Silva et al, 2011). However, variations in pericarp color make it difficult to consistently select Swingle citrumelo fruits for high physiological quality seed production (Rena et al, 2005).…”

“…However, variations in pericarp color make it difficult to consistently select Swingle citrumelo fruits for high physiological quality seed production (Rena et al, 2005). Moreover, characterization of fruit ripening stages based on visual color make standardization of fruit selections problematic (Hamilton et al, 2007;Silva et al, 2011). Color is a perceptual phenomenon that depends on the observer and the conditions in which the color is detected (Pathare et al, 2013).…”