Abstract
Green spear yield of 16 asparagus cultivars originating from six countries was assessed from 2011 to 2013. There were considerable differences in total, marketable and early yields between the cultivars. The quality of harvested spears also varied remarkably. On average, the highest mean total and marketable yields from 3 years of investigation came from Dutch cultivars ‘Gijnlim’ and ‘Cumulus’ and German cv. ‘Mondeo’. The lowest yields were found in New Zealand cultivars ‘Pacific Challenger’ and ‘Pacific 2000’. The greatest mean marketable spear weight was recorded for ‘Cumulus’, whereas the smallest spear weight was obtained from ‘Pacific 2000’, ‘H666’ and ‘NJ 953’. Cultivars ‘Gijnlim’, ‘Cumulus’ and ‘Mondeo’ produced the highest early yields, while ‘Pacific 2000’ and ‘Pacific Challenger’ produced the lowest.
In order to determine the dependence between summer stalks size of tested cultivars in the preceding year and their yields in the following year, regression equations and their correlation coefficients were estimated. The size of summer stalks was expressed as plant growth index, which was the multiplication of height and total cross-sectional area of summer stalks. There was a significant and positive correlation between plant growth index of tested cultivars and their yields in the next vegetation period. The correlation coefficients between these two parameters amounted to 0.62 and 0.68 in 2011/2012 and 2012/2013, respectively