Shoot growth, fruit production and return bloom in 'Conference' and 'Doyenne du Comice' treated with Regalis (prohexadione-calcium).

摘要

The effect of Regalis (prohexadione-calcium) on pear (Pyrus communis) cultivars Conference and Doyenne du Comice was compared to the formerly used growth retardant chlormequat chloride (CCC) in experiments carried out from 1998 to 2001 in Randwijk, Netherlands. In 1998 and 1999, Conference trees on quince MC received 1, 2, 3 or 4 applications of 0.5 or 1.0 kg Regalis/ha. In 1999, Coyenne du Comice trees on quince MC were sprayed twice with 1 or 2 kg Regalis/ha. Also, in 1999, Doyenne du Comice on quince MC were sprayed 3 times with 2 kg Regalis/ha. In all the experiments, the first application of Regalis was performed when the young shoots had developed 5-6 leaves and were ~6 cm in length. In the case of multiple sprays, the interval between consecutive sprays was 14 days. Like CCC, multiple applications of Regalis reduced cumulative shoot growth in both pear cultivars. Reduction in cumulative shoot length of the trees resulted from both a reduction in average shoot length as well as number of shoots longer than 10 cm. Mostly, the reduction in average shoot length was somewhat stronger than that in number of shoots longer than 10 cm. Compared to CCC, return bloom of Regalis-treated trees was generally less. Regrowth of shoots and loss of terminal flower buds were noted to be one of the reasons for reduced return bloom. It is recommended not to use too high rates of Regalis and to use additional alternative methods for growth reduction, such as root pruning or trunk incision..