Containerized transplant production of asparagus: Effects of nitrogen supply and container cell size on plant quality and stand establishment

Greenhouse, containerized, transplant production is a standard procedure for many vegetable species, but is seldom used for asparagus field transplanting. 'Gijnlim' asparagus (Asparagus officinalis L.) seedlings were grown for 12 weeks in a greenhouse during spring to investigate the effect of nitrogen (N) concentration in the nutrient solution and container volume (CV) on transplant quality. The transplants then were field planted to determine the effects of the nursery treatments on plant growth. Five N concentrations (4, 8, 15, 30 and 60 mmol l(-1)), given in five applications of 50 ml each, and two CV (500 and 1000 cm(3), respectively) were tested. Shoot number and area, shoot, root and total dry weight and RGR increased by increasing N concentration. Shoot, root and total dry weight and root weight ratio (PWR) were greater in plants grown in 1000-cm(3) CV than in those grown in 500-cm(3) CV. RWR ranged between 0.5 and 0.6, cm depending on the treatment. Greater partitioning toward the roots was found in seedlings grown at reduced N (4, 8 and 15 mmol l(-1)) concentration in the nutrient solution, regardless of the container size. At the greatest N concentrations (30 and 60 mmol l(-1)), RWR values were lower, particularly in seedlings grown in 500-cm(3) CV. N concentration in the nutrient solution can be increased up to 30 mmol l(-1), without causing an efficiency dropping in growth rates. At the end of the first growing season, 18 weeks after planting in the field, plants originally grown in bigger container size were superior in number of shoots than those grown in the other container size. Nitrogen effect was neither detected on shoot number nor on shoot dry weight.