Asparagus production from autumn to winter in Japan: current status and novel techniques of the Fusekomi forcing culture
In Japan, asparagus (Asparagus officinalis) is mostly harvested from early spring to late autumn. Some farmers use Fusekomi forcing culture in order to harvest asparagus during the winter season. This method includes the following steps. 1) Seeds are sown in cell trays in February and grown in a nursery until April. 2) The seedlings are planted in an open field in late April, and then grown until October. 3) The rootstocks are then dug up after cutting the ferns and densely planted in a Fusekomi heating system set in a greenhouse. 4) The soil is kept warm for allowing spears to grow in winter (from December to February). In this technique, the degree of dormancy breaking by subjecting to chilling temperatures is a key factor for obtaining high yield. The target rootstock weight is between 1.5 and 2.0 kg, and, when dormancy is broken, the yield could be expected to reach 270-350 g per rootstock. However, because of the shortage of exposure to chilling temperatures, breaking dormancy and harvesting spears in November are difficult. In this study, we modified the Fusekomi forcing technique to control the yellowing of ferns and the dormancy of rootstocks. The rootstocks were dug up with green ferns and left in an open field to expose them to dryness and chilling temperatures. After ferns became yellow, they were cut, and the rootstocks were placed in a refrigerator (5°C). Because of this treatment, the sugar content of the storage roots increased markedly, dormancy was broken, and harvesting in November was possible. Results of this study showed that harvesting asparagus from autumn to winter by using our modified technique allowed obtaining marketable yields.
Yamaguchi, T. and Maeda, T. (2020). Asparagus production from autumn to winter in Japan: current status and novel techniques of the Fusekomi forcing culture. Acta Hortic. 1301, 11-116
Asparagus officinalis, winter harvest, dormancy, rootstock, yellowing