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

Abstract

Additional index words. cladode, flowering, fruit quality, bagging, pests and diseases, sunburn Abstract. To evaluate the comprehensive response of commercial cultivation of the whitefleshed 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), mmol · m L2 · s L1 ] 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 noncurrentyear 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.

High Temperature Suppresses Fruit/Seed Set and Weight, and Cladode Regreening in Red-fleshed ‘Da Hong’ Pitaya (Hylocereus polyrhizus) under Controlled Conditions

“…'Da Hong', also known as 'Big Red', is an elite red-fleshed cultivar preferred by growers in Taiwan and Southeast Asia because of its favorable traits including self-compatibility, abundant yield, large fruit (more than 400 g per fruit), and high total soluble solid content (TSSC, above 20°Brix) (Jiang and Yang, 2015;Liu et al, 2015). However, unlike the redfleshed cultivar Fu Gui Hong or VN White, a white-fleshed pitaya (H. undatus) cultivar, Da Hong does not produce high fruit yield all of the year in Taiwan (Chien and Chang, 2019). It has been found that although 'Da Hong' produces the most abundant flowers and fruits during the hottest period (August to September), the fruits are small (less than 150 g) and the color of the cladode becomes yellow under field conditions (Y.C.…”

“…Although pitaya has a crassulacean acid metabolism (CAM) characteristic, it is prone to yellowing of the cladode, i.e., slight sunburn with no incidence of necrosis on the sunny (sun-exposed) side of the adaxial cladode that has three flat wavy ribs with one sunny side and two shaded sides in redfleshed pitaya, during the hot season in Taiwan, followed by regreening during cooler seasons (Chien and Chang, 2019). Of the pitayas, the cladode of the white-flesh pitaya displays the highest total daily net uptake of CO 2 at day/night air temperatures of 30/20°C, but the total daily net uptake of CO 2 falls remarkably at 40/30°C (Nobel and De la Barrera, 2002), indicating that dry matter accumulation may be affected by temperature regimes.…”

An Insect- and Rain-Proof Net Raises the Production and Quality of Chinese Bayberry by Preventing Damage From Insects and Altering Bacterial Communities

“…However, traditional strategies to protect the fruits by using insecticides may pose residual risks to the fruit, the environment and human health ( Devine and Furlong, 2007 ); in addition, application of insecticides may not completely eliminate the insects, possibly due to the development of insect resistance ( Sparks et al, 2020 ), as confirmed by the results of our study ( Figure 1C ). IPNs are suitable tools for insect control ( Formisano et al, 2020a ) and have been widely used on vegetables, melons and fruits ( Chien and Chang, 2019 ; Formisano et al, 2020b ). However, the effects of IPNs on Chinese bayberry fruits have not yet been reported.…”

Heat Stress Leads to Poor Fruiting Mainly Due to Inferior Pollen Viability and Reduces Shoot Photosystem II Efficiency in “Da Hong” Pitaya

“…During the peak of summer (June-August) in Taiwan, the day and night temperatures are close to 35 • C and 25 • C, respectively [15]. Under this environment of high light intensity and elevated temperature, the sun-exposed shoots at the adaxial end often burn and exhibit yellowing, and the yellowed shoots naturally re-green in autumn (October) when the temperature decreases [15]. During HT, a 50% sunshade net placed above the canopy can lower the temperature and reduce the yellowing of shoots [15][16][17][18].…”

“…Under this environment of high light intensity and elevated temperature, the sun-exposed shoots at the adaxial end often burn and exhibit yellowing, and the yellowed shoots naturally re-green in autumn (October) when the temperature decreases [15]. During HT, a 50% sunshade net placed above the canopy can lower the temperature and reduce the yellowing of shoots [15][16][17][18]. However, compared with the findings in an open field, the yellowing of shoot in plants cultivated in a netting facility is not improved even though the light intensity is reduced, owing to the increase in temperature [15].…”