Efeito da data de arranque no viveiro e do tratamento pelo frio no crescimento e produtividade do morangueiro (Fragaria x ananassa Duch.)

The aim of this study was to evaluate the effects of digging date at the nursery and duration of cold storage treatments applied after digging on the vegetative growth, flower production and fruit quality of two Californian short-day cultivars, "Chandler" and "Douglas", when winter planted in south-west Portugal. During four consecutive years, three field (1991/92, 1992/93 and 1993/94) and one growth chamber (1994/95) trials were layer out with three digging dates (middle of October, beginning and middle of November) and three cold storage treatments at 2#+-#1deg C (0,2 and 4 weeks). vegetative and flowering responses to digging dates and cold storage treatments varied between years and cultivars. The highest productivity of both cultivars was obtained with the 3"r"d digging date with no cold storage treatment. However, in 199394, when the plants had received a greater number of chilling hours in the nursery, chilling had an inhibitory effect on flower production of "Chandler" dug on the latest date, resulting in reduced fruit yield and increased vegetative vigor. "Douglas" had a relatively high chilling requirement compared to "Chandler" and did not respond to early chilling. Increased field chilling promoted higher leaf and stolen numbers and greater leaf area in both cultivars, and also higher crown number in "Chandler" and petiole length in "Douglas". Additional cold storage treatments stimulated vegetative development and decreased flower and inflorescence number. However, in 199192, when the plants received less number of chilling hours in the nursery, cold storage treatment in early digging dates increased plant productivity. Inflorescence number per plant was the main yield component responsible for differences in yield between years, Thus, improving growing conditions, namely by increasing the temperature in the winter months (January and February) will improve plant productivityAvailable from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1200 Lisboa / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga