Pot-grown Strawberry Research Articles

Effects of Root-zone Cooling with Short-day Treatment in Pot-grown Strawberry (<i>Fragaria</i> × <i>ananassa</i> Duch.) Nurseries on Flowering and Fruit Production

Effects of Root-zone Cooling with Short-day Treatment in Pot-grown Strawberry (<i>Fragaria</i> × <i>ananassa</i> Duch.) Nurseries on Flowering and Fruit Production

The Effects of High Temperature and Water Stress on Fruit Growth and Anthocyanin Content of Pot-grown Strawberry (Fragaria×ananassa Duch. cv. ‘Sachinoka’) Plants

We investigated the effects of high temperature and water stress on fruit growth and levels of anthocyanins and their precursors in pot-grown strawberry (Fragaria×ananassa Duch.) plants. Nursery seedlings in pot were grown at a greenhouse. For simplicity, fruit set was fixed at one per plant. After pollination by honeybees, plants were transferred to growth chambers for high temperature (30/15°C day/night) or control (20/15°C) treatments, both with a 14L/10D photoperiod. Water stress was applied in both temperature regimes. After fruit weights were measured, the fruits were divided into three portions: inner (pith), middle (cortex), and outer parts. The anthocyanin, flavonoid, and cinnamic acid derivative contents were then analyzed. The harvest time (days after anthesis) was shorter at the high temperature. Anthocyanin content decreased in all three parts of the fruit at high temperature but was not affected by water stress. Cinnamic acid derivative content decreased (but not significantly) in all three parts of the fruit at high temperature but flavonoid content did not differ from the levels in the control. In the anthocyanin biosynthesis pathway, high temperature affected for anthocyanins and cinnamic acid derivatives inside the strawberry fruit.

Water Relations and Abscisic Acid in Pot-grown Strawberry Plants under Limited Irrigation

We investigated the effect of full irrigation (FI), deficit irrigation (DI), partial root zone drying (PRD), and nonirrigation (NI) on soil and plant–water relations, leaf stomatal conductance (gs), and abscisic acid (ABA) concentration in the xylem sap ([ABA]xylem) of pot-grown strawberry plants (Fragaria ×ananassa cv. Honeoye) in a greenhouse experiment. The DI and PRD treatments, irrigated with 70% of the volume of FI, reduced soil water content (θ), whereas crown water potential (ψcrown), leaf water potential (ψleaf), and gs were only significantly reduced from 11 to 15 days after initiation of irrigation treatments. Although [ABA]xylem was not significantly affected by the DI and PRD treatments, the NI plants increased [ABA]xylem, which coincided with decreased ψcrown, ψleaf, and gs 3 to 4 days after withholding irrigation. When ψcrown dropped below a critical value of −0.4 MPa, [ABA]xylem was linearly correlated with ψcrown. The gs tended to decrease as a function of [ABA]xylem, but gs was also affected by the water vapor pressure deficit (VPD) of the air. It is concluded that we did not observe a significant difference between strawberry plants grown in PRD and DI because ψcrown had to be below −0.4 MPa and soil water potential (ψsoil) had to be below −0.25 MPa before [ABA]xylem increased, these values were only reached toward the end of the experimental period (11–15 days after initiation of irrigation treatments).

EFFECT OF HIGH TEMPERATURE ON FRUIT QUALITY OF POT-GROWN STRAWBERRY PLANTS

We investigated the effect of high temperature on the fruit quality of pot-grown strawberry plants with a limited number of fruit in greenhouse and growth chamber experiments. In the greenhouse, plants were grown under either normal greenhouse (control) temperatures or in a small plastic tunnel, which held the air temperature a few degrees higher than the control. In the growth chamber, the air temperature was set to either 35/20°C (day/night) or 25/20°C. The fruits weight content showed no relation to temperature regime. Ascorbic acid content was not influenced by high temperature in either experiment. However, the anthocyanin content was decreased at high temperature in the growth chamber. Because the periods from anthesis to harvesting were almost the same in both temperature regimes, high temperature might reduce the internal content of anthocyanins in marketed fruits.