光質及溫度對白草莓植株生長及果實色澤之影響

Abstract

白草莓(Fragaria × aananassa Duch.)果實表面呈現白色或淺粉色，而果肉內部則呈白色，與商業紅草莓有顯著區別。於台灣露天栽培時，白草莓果實會有過度呈色及著色不均的情形。本研究針對環境因子對白草莓生長及果實色澤的影響，分為兩部分，試驗一為比較栽培於台北及台中兩地區之白草莓植株生育差異，試驗二及三則以調控的光質及溫度組合處理，探討兩因子對白草莓植株生育及果實色澤的影響。試驗材料為三果色不同之白草莓品系，白果‘芎林3號’、粉白果‘長治1號’及橘紅果‘長治2號’，以7吋盆苗進行試驗，試驗一每地區10株重複，試驗二及三每處理6株重複。 各品系白草莓以栽植於台中的植株營養生長較佳，有較多葉片數及花序累積量，於台北生長之植株葉柄長及葉面積較長。在果實色澤方面，以栽植於台北的果實a*值顯著較低，白果‘芎林3號’及粉紅果‘長治1號’的果實無明顯轉色。台中地區果實的總花青素含量顯著高於台北地區果實約3倍。因此，白草莓以栽植於台北地區較能維持白果之特性。 光質及溫度組合處理試驗中，分別以四種光質：紅光(654 nm)、藍光(453 nm)、紅藍混光(R:B = 7:3)及白光(430-680 nm)，組合兩種日夜溫22/18oC及28/25oC，於植株生長至五六片葉開始連續處理18週。植株營養生長表現，以紅光處理植株之平均葉柄長最長、葉面積最大，而藍光處理則使葉柄短縮且葉面積較小。溫度對植株生長的影響，以28/25oC的植株葉柄長較長。果實色澤在22/18oC下，各品系白草莓皆以紅光照射的果實最無轉色，其a*值為0.8~2.7，果實總花青素含量63.4~133.7μg/g，顯著低於藍光處理之果實(a*值5.6~6.0、總花青素含量227.7~276.7μg/g)。高溫影響草莓開花及著果，各品系中僅‘長治2號’可在28/25oC下正常產果。以橘紅果‘長治2號’與紅果‘豐香’進行相同的光質及溫度組合處理，光質及溫度不影響‘豐香’果實呈色及總花青素含量，在各種處理下的果實皆為紅色。‘長治2號’於28/25oC下，果色較紅，果實總花青素含量為158.3μg/g，亦較22/18oC的果實總花青素含量為高。同樣於22/18oC下，以紅光處理下的‘長治2號’，果實總花青素含量為112.1μg/g，而藍光下的果實總花青素含量則為201.2 μg/g，顯示藍光對白草莓果實花青素生合成誘導效果較顯著。 白草莓以果色白為其特點，為了維持白草莓果實特色及價值，建議栽培地區以北台灣較中台灣適合；若於可控環境下栽培，則建議以紅光及低溫處理，較能維持白草莓的果實品質並維持白果色的特徵。

White strawberry (Fragaria × ananassa Duch.) has white or pink skin color of the fruit, while the color of flesh is white, which is significantly different from the commercial red strawberry. The white strawberry fruit would be excessive-colored and unevenly colored when cultivated open field in Taiwan. This experiment was divided into two aspects for the influence of environmental factors on the growth and fruit color of white strawberry, the expetiment 1 was to compare the effects of white strawberries cultivated in Taipei and Taichung location. The expetiment 2 and 3 were about light quality and temperature treatment to discuss the growth of white strawberry and the coloration of fruits. The experimental materials were three white strawberry varieties with different fruit colors, white-colored ‘Chiung-lin No.3’, pink-colored 'Chang-zhi No.1 ' and orange-colored ‘Chang-zhi No.2’. The experiment was conducted with 7-inch pot seedlings. The experiment 1 repeated 10 plants for each location, and experiments 2 and 3 repeated 6 plants for each treatment. The three varieties of white strawberry cultivated in Taichung had better nutritional growth, with more leaf number and inflorescence accumulation. While the plants cultivated in Taipei had larger petioles and leaf area. In terms of fruit color, the a* value of the fruits cultivated in Taipei was significantly lower, and the fruits of ‘Chiung-lin No.3’ and 'Chang-zhi No.1 ' had no significant coloration. The anthocyanin content of the fruits in Taichung was significantly higher than that in Taipei by about three times. Therefore, the three varieties of white strawberry planted in Taipei could be better to maintain the characteristics of the fruit. The light quality and temperature treatment,utilizing four light quality, including red light (654 nm), blue light (453 nm), red-blue light (R:B = 7:3) and white light (430-680 nm) were combined 22/18oC and 28/25oC of temperatures treatment. When the plants grew to five or six leaves, it was treated continuously for 18 weeks. The vegetative growth of the plant, the petiole length and leaf area with red light treament was higher than other treatments. While the blue light treatment which would shorten the petiole length and reduce the leaf area. With temperature treatment, the petiole length at 28/25oC was longer. The the color of the fruit, at 22/18oC, three varieties of white strawberries had no significant coloration under red light treatment. The a* value of red light treatment of fruits was 0.8~2.7 and the total anthocyanin content was 63.4~133.7μg/g, which was significantly lower than blue light treatment (the a* value was 5.6~6.0 and the total anthocyanin content was 227.7~276.7μg/g). The three varieties of white strawberries, merely ‘Chang-zhi No.2’ could produce fruits normally at 28/25oC. With 'Changzhi No. 2' and ‘Fengxiang’red strawberries for the same light quality and temperature treatment, the light quality and temperature have no significant difference in color and anthocyanin content of 'Fengxiang’, which color of fruits were red under various treatments. The ‘Chang-zhi No.2’ had a reddish skin color of the fruit at 28/25oC, with an anthocyanin content of 158.3μg/g, which was also higher than that at 22/18oC. At 22/18oC and red light treatment, the coloration of fruit was lighter in red, which anthocyanin content was 112.1 μg/g. The anthocyanin content under blue light treatment was 201.2 μg/g, indicating that blue light has a significant effect on the induction of anthocyanin biosynthesis of white strawberry. White strawberry is characterized by white fruit color. In order to maintain the characteristics and value, it is recommended that cultivating the white strawberries in north of Taiwan is more suitable than medium of Taiwan. If cultivated in controlled environment, it is recommended to use red light and low temperature treatment to maintain the fruit quality and the characteristics of white peel color of fruits.