New asparagus cultivars suitable for outdoor cultivation in Hokkaido, Japan

Biomass production and spear productivity of plants of new cultivars were investigated in Hokkaido, comparing with established cultivars in Japan. The nurseries of 3 established cultivars (‘UC-157’, ‘Grande’ and ‘Gijnlim’) and 3 new cultivars (‘Vegalim’, ‘Atticus’ and ‘Cumulus’) were planted in the Experimental Farm in Hokkaido university on July 2, 2014. Growth index (G.I) of the fern was measured to evaluate the biomass production on Nov 4, 2016. Above ground biomass (AGB) of each cultivar was cut, and then the fresh weight and dry weight were measured on Dec 4, 2016. Green spears, 24 cm in length, were harvested for 6 weeks, 2017. And then canopy structure, photon flux density and foliage by layers of 4 years old plants were evaluated. Regarding G.I there was no significant difference among used cultivars in 2016. Dry weight (DW) of AGB in ‘Grande’ was higher than other cultivars in 2016. New cultivar ‘Atticus’ tended to produce large spears and lager marketable and total yield compared with other cultivars. ‘Vegalim’ had tighter heads compared to other cultivars in 2017. The relationship between AGB and spear yield was not certain. ‘Grande’ had large biomass production but small yield. The spear yield was relatively large in spite of small fern DW in ‘Atticus’. There were significant differences in canopy structure among the cultivars. The light transmittance showed obvious differences over different layers among the cultivars.