Mineral Elements Concentrations in Cladodes, Floral Bud Induction and Screening Lines for Canker Disease-resistance in Pitaya (Hylocereus spp.)

• Main Authors: Jia Hui Lee, 李家輝
• Other Authors: Huey-Ling Lin
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/09571581784645547188

碩士 === 國立中興大學 === 園藝學系所 === 103 === In recent years, the production area of pitaya incresed gradually, therefore new problems also arised. Pitaya production may face problems such as nonstandard fertilization, unstable lighting and severe stem canker disease which in turn resulted in excessive fertilization, overuse of energy and discarding of orchard. In this study, we investigated the variation of mineral elements in pitaya cladodes, to provide a reasonable fertilizer application method and to develop a new forcing culture method aiming to reduce energy waste. Meanwhile, some pitaya lines were collected from local market to screen for disease-resistance which can be applied in future breeding program. Pitaya cladode mineral composition was investigated in January, March and July, we found that the mineral composition of young pitaya cladodes showed large variations, compared to old pitaya cladodes. Nitrogen, phosphorus, calcium and iron concentration decreased, but potassium, magnesium, manganese, zinc and copper concentration increased. Changes of mineral composition in old pitaya cladodes were smaller, compared to young pitaya cladodes. Variation pattern of mineral composition in two different ages of pitaya were the same , but changes of magnesium and manganese contents were found to be different in young pitaya cladodes compared to old pitaya cladodes. Mineral composition of pitaya cladodes may vary from place to place. In adition, young pitaya cladodes have high potassium content and old pitaya cladodes have high calcium content. Mineral composition of pitaya cladodes was not correlated to mineral composition of soil but may vary in different variaties.Young pitaya cladodes contained 0.99~1.48% nitrogen, 0.15~0.32% phosphorus, 2.64~4.69% potassium, 0.71~1.99% calcium, 0.37~0.80% magnesium, 11~32ppm iron, 8~37ppm manganese, 20~38ppm zinc, and 0.3~7ppm copper. In contrast, old pitaya cladodes contained 0.78~1.11% nitrogen, 0.19~0.58% phosphorus, 0.92~3.05% potassium, 2.49~6.01% calcium, 0.43~1.08% magnesium, 8~28ppm iron, 18~65ppm manganese, 30~40ppm zinc, and 0.1~4ppm copper. The best timing to treat Vietnam plant growth regulator VSL 1 was in June and July. Application of VSL 1 in June and July can achieve 20% and 22% of floral induction rate in young pitaya cladode and 9% and 20% in old pitaya cladode, respectively. VSL 1 treatment was unable to induce floral induction in pitaya if treated during the period from November to the next May. Flower bud formation was visible three days after VSL 1 treatment. In addition, fruit quality after treatment with VSL 1 was not significantly defferent from the normal season fruit in terms of fruit weight, fruit length, number of sepals, peel thickness, total soluble solids content and titratable acidity. All CPPU and GA3 mix solutions can induce flower bud formation and 3.55~6.7cm long stalk formation. Furthermore, fruit qualities such as fruit weight, fruit length, fruit width, number of sepals, peel thickness, total soluble solids content, titratable acidity and firmness were similar to normal season fruit after application of CPPU and GA3 mixed solution. Results from pitaya stem canker disease-resistant line selection indicated that stingless and Penghu red pitaya lines were the best candidates. During our initial disease-resistant test, stingless and Penghu red pitaya line showed 3.85% and 7.69% of canker incidence in young pitaya cladode 28 days after inoculation and 0% and 3.85% of canker incidence in old pitaya cladode, respectively. Twenty one days after Neosyctalidium dimidiatum inoculation, Yilan red pitaya line showed at least 80% of canker incidence indicating that Yilan red pitaya line was not resistant to pitaya stem canker. Result from our second test demonstrated that stingless pitaya line had 11.11% of canker incidence 21 days after Neosyctalidium dimidiatum inoculaton. In contrast, Yilan red pitaya line had 95.56% of canker incidence. Our results also suggested that all ages of pitaya cladodes can be infected by Neosyctalidium dimidiatum with 1-week-old pitaya cladode being the most volunerable which had 84.45% of canker incidence 7 days after Neosyctalidium dimidiatum inoculation and 100% of canker incidence 21 days after inoculation. One-month-old (maturity) and 3-month-old pitaya cladodes were more resistant to stem canker disease which showed 40% and 36.67% of canker incidence 21days after Neosyctalidium dimidiatum inoculation, respectively.