Growth and Physiological Responses of Salak Cultivars (Salacca zalacca (Gaertn.) Voss) to Different Growing Media

The study to investigate growth and physiological responses of salak cultivars to different growing media was carried out in a greenhouse of the Institute for Horticultural Sciences, Department of Fruit Sciences of Humboldt University Berlin at Berlin. The temperature inside the greenhouse were adjusted to 20 °C/25 °C (day/night) and the relative humidity varied between 20 % and 70 %. Pure quartz sand, peat and a sand/compost mixture were tested as growth substance. The following parameters were measured- shoot dry weight, root dry weight, shoot length increment, leaf area increment, net CO2 assimilation rate (PN), leaf colour and plant mineral contents (N, P, K, Ca and Mg). Quartz sand, supplied with a complete nutrition solution was the best growing medium, whereas low pH peat was not suitable for salak seedlings due to the inhibitory growth effect. “Pondoh hitam†was the most vigorous cultivar.