Broccoli yield and quality can be determined by cultivar and temperature but not photoperiod in south-east Queensland

Abstract

Summary. Understanding of genotype and environment interactions will help farmers optimise broccoli (Brassica oleracea L. var. italica Plenck) yield and quality, by matching cultivars to time of sowing. Limited information is available on the effect of temperature and photoperiod on broccoli yield and quality. The objective of this study was to quantify the temperature and photoperiod responses of yield and quality attributes in a subtropical environment. Three cultivars (‘Fiesta’, ‘Greenbelt’ and ‘Marathon’) were sown on 8 dates from 11 March to 22 May 1997. Plants were grown under natural and extended (16 h) photoperiods at Gatton College, south-east Queensland, under non-limiting conditions of water and nutrient supply. Climatic data, dates of emergence, floral initiation, harvest maturity, and yield and quality data were recorded. As growing season mean minimum temperature decreased, fresh weight of tops decreased linearly while fresh weight harvest index increased linearly. However, there was no definite relationship between fresh weight of tops or fresh weight harvest index, and growing season mean minimum temperatures ≥10ºC. Quality attributes were determined more by genotype than environment. ‘Fiesta’ had the best quality, with higher head shape and branching angle ratings than Greenbelt and Marathon. Bud colour and cluster separation ratings of Marathon were only suited for export when growing season mean minimum temperatures were <8ºC. Photoperiod did not influence yield and quality in this study.