Nutritional and gibberellic acid requirements in kiwifruit vitroponic cultures

Summary Residual macronutrients, carbon source, and gibberellic acid (GA₃) in the culture medium were measured throughout the whole culture period of kiwi (Actinidia deliciosa Chev. cv. Hayward) explants cultured in liquid medium using cellulose plugs as explant support. The objective of this study was to adapt the composition of the culture medium to an automated culture system with the possibility of applying 6-benzyladenine pulses so as to improve the efficiency of kiwifruit micropropagation. Ammonium and phosphate were the most consumed ions at the end of the culture period (35 d). Murashige and Skoog medium might be too rich for the culture of kiwifruit in liquid medium except with respect to phosphate which decreased significantly toward the end of the culture period. Sucrose, and the glucose resulting from the hydrolysis of the former, were taken up by the kiwi explants throughout the whole culture period. GA₃ absorption by the kiwi explants occurred gradually throughout the subculture, although 67% of this initially added plant growth regulator remained in the culture medium at the end of the 35-d culture period.