Dragon Fruit Network

Articles

2019/04/30

Net Houses Effects on Microclimate, Production, and Plant Protection of White-fleshed Pitaya

To evaluate the comprehensive response of commercial cultivation of the white-fleshed pitaya (Hylocereus undatus ‘VN White’) under net house in Taiwan, experiments were conducted during the natural reproductive period (from June to Sept. 2016) with fruits grown within net houses (either 16 or 24 mesh insect-proof netting, without fruit bagging) or in an open field (the control, without netting, with fruit bagging). The effects of netting on microclimate, phenological period, flowering (floral bud emergence) of current and noncurrent cladodes (shoots) (2- to 3-year-old), fruit quality, market acceptability, pests and diseases control, and level of sunburn were investigated. Indoor solar radiation in the 16 and 24 mesh net houses were 78.12% and 75.03%, respectively, and the sunlight intensities [photosynthetic photon flux density (PPFD), μmol·m−2·s−1] were 76.03% and 73.00%, respectively, that of control. The maximum daily temperature for the 16 and 24 mesh net houses was greater than that of the control. However, there were no significant differences in daily average temperature, minimum temperature, or relative humidity (RH). The first flowering cycle (12 June 2016) and last flowering cycle (11 Sept. 2016) in both net houses were the same as those in the control. The accumulative flowering of current cladodes was unaffected by net covering, but that of noncurrent-year cladodes in both net houses was lower than that in the control. Although the L* and C* values of fruit color in the 16 and 24 mesh net houses were lower than those in the control, the fruits still had commercial value. The average fruit weight of the 16 mesh net house was significantly greater than that of the control. Average total soluble solid (TSS) content, TSS content at the fruit center, and titratable acidity were unaffected. In addition, the 16 mesh net house blocked some large pests without exacerbating disease or sunburn. Our findings suggest that 16 mesh net houses may be useful for white-fleshed pitaya cultivation during its natural reproductive period in subtropical Taiwan.

Dietary dragon fruit (Hylocereus undatus) peel powder improved in vitro rumen fermentation and gas production kinetics

Plant phytophenols especially condensed tannins (CT) and saponins (SP) have been demonstrated to impact on rumen fermentation. Dragon fruit (Hylocereus undatus) peel powder (DFPP) contains both CT and SP. The current study aimed to investigate the influence of DFPP and varying levels of concentrate and roughage ratios on gas production kinetics, nutrient degradability, and methane production “using in vitro gas production technique.” The dietary treatments were arranged according to a 3 × 5 Factorial arrangement in a completely randomized design. The two experimental factors consisted of the roughage to concentrate (R:C) ratio (100:0, 70:30, and 30:70) and the levels of DFPP supplementation (0, 1, 2, 3, and 4% of the substrate) on DM basis. The results revealed that the R:C ratio at 30:70 had the highest cumulative gas production when compared to other ratios (P < 0.01). The in vitro true dry matter degradability at 12 and 24 h was affected by R:C ratio (P < 0.01). Furthermore, volatile fatty acids (VFA) and propionate (C3) were significantly increased by the levels of DFPP, while acetate (C2) and C2:C3 ratios were decreased (P < 0.05). The rumen protozoal population was significantly decreased by DFPP supplementation (P < 0.05). Rumen methane production was significantly impacted by R:C ratios and decreased when the level of DFPP increased (P < 0.01), while NH3-N and ruminal pH were not influenced by the DFPP supplement. It could be summarized that supplementation of DFPP resulted in improved rumen fermentation kinetics and could be used as a dietary source to mitigate rumen methane production, hence reducing greenhouse gas production.

Dissipation pattern of azoxystrobin and difenoconazole in red dragon fruit (Hylocereus polyrhizus) cultivated in Indonesian highland (West Java) and coastal area (D.I. Jogyakarta) and its implication for dietary risk assessment

Background
Cultivation of red dragon fruit (Hylocereus polyrhizus) in Indonesian orchards is hampered by anthracnose and stem canker. A mixture of azoxystrobin 200 g/L + difenoconazole 125 g/L is recommended in supporting the obligated integrated pest management. For the consumer safety, dietary intake of the residues from fresh edible part should be assessed; therefore, information on correct dissipation pattern of the applied pesticide is required.
Materials and Methods
Field residue trials in Indonesian highland (West Java) and coastal area (Special Region of Yogyakarta) were done at recommended dose was 0.151 kg ai/ha azoxystrobin and 0.094 kg ai/ha difenoconazole, three times at 10 days interval. Whole fruit samples were collected at 70%–100% ripeness at −1, 0, 1, 3, 7, 10, and 14 days after last application, processed and determined its residue as soon as possible.
Result and Discussion
Photoisomerization of azoxystrobin was observed at Day 0, especially in coastal area; however, it has been dissipated to below lowest validated level in the following day. At Day 0, 3%–5% of the deposited azoxystrobin and difenoconazole penetrate into the flesh; however, most residues (95%–97%) were retained in peel, and dissipated in prolonged day. The dissipation pattern was non-linear. The dissipation data were better fit with bi-exponential double-first-order in parallel than single first-order kinetics model. The DT50 of both azoxystrobin and difenoconazole was 3 days. At harvest time, seventh day, only azoxystrobin residue was detected in flesh at 0.006 mg/kg; therefore, the long-term dietary risk was 0 per cent acceptable daily intake.
Conclusion
Fresh red dragon fruit is safe to consume.

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Articles

Net Houses Effects on Microclimate, Production, and Plant Protection of White-fleshed Pitaya

Dietary dragon fruit (Hylocereus undatus) peel powder improved in vitro rumen fermentation and gas production kinetics

Dissipation pattern of azoxystrobin and difenoconazole in red dragon fruit (Hylocereus polyrhizus) cultivated in Indonesian highland (West Java) and coastal area (D.I. Jogyakarta) and its implication for dietary risk assessment