Department of Horticulture, Daegu University1
Raising seedlings is important for fruit crops and is especially significant for strawberries as it accounts for 80% of their cultivation. However, there are few studies on raising seedlings of strawberries by hydroponics. Since strawberries show clear differences in growth characteristics based on cultivar, it is necessary to develop suitable fertilizer formula, concentration and pH for each cultivar, and also to examine the amount of nutrient feeding appropriate for each medium type. A key to raising seedlings of strawberries by hydroponics is the development of strategies to manage the concentration of nutrient solution. The mother plants of ‘Daewang’ strawberries were planted on hydroponics benches filled with cocopeat on March 28, 2012. Three nutrient solution treatments were employed during the term of raising seedlings: a type that supplied EC 0.6 dS･m-1 nutrient solution for 30 days and only water for 20 days [0.6 (30) + 20]; a type that supplied EC 1.2 dS･m-1 nutrient solution for 30 days and only water for 20 days [1.2 (30) + 20]; and a type that supplied EC 1.2 dS･m-1 nutrient solution for 50 days [1.2 (50)]. The plants were then planted on hydroponics benches filled with cocopeat on September 20, and managed with EC 0.6-0.8 dS･m-1 strawberry nutrient solution developed by Yamazaki. After planting, shoot growth, flowering rate and fruit quality of the first cluster were investigated. The petiole length, leaf length, leaf width and crown diameter showed the highest grown in the [1.2 (50)] treatment, followed by [1.2 (30) + 20], and then [0.6 (30) + 20], indicating that the higher concentration of nutrient solution was preferable for raising seedlings. However, the growth differences among treatments gradually disappeared as growth continued, and the crown diameter especially grew to exhibit almost no difference at all among treatments. The point of flowering came first in [0.6 (30) + 20], followed by [1.2 (30) + 20] and then [1.2 (50)]. The [0.6 (30) + 20] treatment showed much earlier flowering than other treatments, which implies that low-concentration nutrient solution may be beneficial to the flowering of ‘Daewang’ strawberries while raising seedlings. There was no statistically significant difference among treatments in fruit length, fruit diameter and fruit firmness. Fruit weight in [1.2 (50)] treatment was significantly higher than other treatments. However, soluble solids of fruit was the lowest in [1.2 (50)] treatment. Together, the results of this experiment imply that it is better to supply EC 0.6 dS･m-1 solution for 30 days and then supply only water for 20 days to adequately manage concentration of nutrient solutions during the period of raising seedlings of strawberries by hydroponics.
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