Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 13, 2013
Publication Date: February 14, 2013
Citation: Takeda, F. 2013. Cultural techniques for altering the flowering time and double-cropping short-day varieties. North American Berry Conference, January 27-30, 2013, Portland, Oregon. http://berrygrape.org. Technical Abstract: July-plugged transplants of short-day cv. Strawberry Festival (Fragaria x ananassa), flowered in October and November even though they were grown under long photoperiods and warm temperatures (greater than 21 degrees C) in July and August. These unexpected results were attributed to a high plant density (320 transplants per meter square) that provided a continuous and heavy leaf cover which eliminated red light (less than 700 nm) from reaching the crowns. This hypothesis was tested by illuminating crowns of transplants growing in 50-cell packs for 16 h per day with red light emitting diode (LED) lamps (maximum wavelength at 662 nm and 80 percent of output between 644 to 674 nm). Red light treatment caused a significant reduction in fall flowering. It is proposed that a high ratio of far red light to visible light reaching the crown will play a role in floral bud induction, possibly as early as mid-August. Transplants of some short-day cultivars started as plug plants in early July have the capacity to flower and fruit in the fall and the following spring, enabling growers in the mid-Atlantic coast region to obtain two harvests within one year from a single planting. Growing strawberry transplants under photoselective net delayed flowering. The no shade control plants began flowering in late September and by late November, more than 90 percent of the plants had bloomed. These plants produced fruit from October to early January. Flowering in plants that were grown under red- or blue-colored shade net did not occur until early January. The results of this study suggested that the photoselective shade net over strawberry plug plants in August blocks the light signal that initiates flowering until the netting is removed, hence delaying the initiation of flower buds until plants are transplanted in the field.