Climate change-induced prolonged water stress (WS) affects crassulacean acid metabolism photosynthesis in pitaya (Hylocereus), limiting crop productivity through insufficient photosynthate. To document how WS/rehydration affects diel photosynthesis, red-fleshed pitaya (H. polyrhizus) micropropagules were studied for 5 weeks in a mannitol-induced water potential gradient replaced with moderate (MWS; −1.0 MPa in week 2; −0.5 MPa for the rest) or intensified (IWS; −1.0 and −1.5 MPa in weeks 2 and 3; −0.5 MPa for the rest) WS in vitro. Net photosynthetic rate (Pn) and integrated net CO2 uptake (INCU) were measured using an Arduino-based photosynthesis system. Micropropagules under MWS had similar Pn in weeks 5 and 1, whereas the control (−0.5 MPa) increased. Pn recovery did not occur after IWS. The average relative INCU was similar in the control and MWS, but lower in IWS. The Pn difference increased with WS, becoming more evident at dawn (Phase II), evening (Phase IV), and predawn the next day (Phase I), and occurred earlier in Phases IV and I under IWS. MWS did not reduce photosynthesis, demonstrating that the photosynthetic regulation could respond to short-term WS in pitaya and indicating the potential of watering for Pn recovery at evening and predawn under IWS.

To meet the increasing demand for year-round production of 'Da Hong' red-fleshed pitaya (Hylocereus polyrhizus), which is limited by its natural flowering season in the summer and has been a dominant cultivar in Taiwan, China and East-SouthEast Asia owing to its self-compatibility and excellent fruit quality, extending the off-season cultivation period has become a crucial endeavor. This study aimed to assess the effects of net-houses and light sources on off-season (spring and winter) fruit quality yield of 'Da Hong' red-fleshed pitaya in Taiwan. Mature six-year-old plants were cultivated either in net-houses or open fields (OFs), with night-breaking achieved using artificial lighting: either 100 W incandescent bulbs (IBs) or 23 W compact fluorescent energy-saving bulbs (CFBs). The study was conducted during spring and winter in 2017-2018, with flowering rate and fruit production evaluated. Floral bud emergence in the net-house+IB and net-house+CFB groups preceded that in other treatments by at least 2 weeks during spring, with net-house+IB exhibiting the highest frequency of flowering waves (four in spring and three in winter). Across all treatments, night-breaking via artificial lighting in spring markedly increased yield, with IBs and CFBs producing similar outcomes. Quality-wise, OF cultivation surpassed net -house cultivation in spring, whereas net -house cultivation, particularly with IBs, proved more effective during winter. In summary, net -house cultivation offers several advantages for off-season production, including earlier peak flowering in spring, increased flowering cycles in both spring and winter, and higher flowering rates during winter. Overall, these results may help enhance and stabilize off-season 'Da Hong' redfleshed pitaya cultivation. Moreover, the significance of our study has the potential to revolutionize the flowering physiology, the strategy to enhance year-round production and the advancement of agricultural sustainability in pitaya.

A non-facultative crassulacean acid metabolism (CAM) profile has been documented in pitaya, in which closed flow photosynthesis systems have been used to evaluate the CAM capacity and characteristics of plants, albeit with overestimation. By contrast, open-flow systems promote measurement reliability and continuously monitor the photosynthetic profile, which has not been reported in pitaya. Therefore, this study aimed to overview the diel gas exchange capacity of Hylocereus polyrhizus 'Da Hong' in an open-flow system, in which the explants were incubated in vitro to prevent measurement deviations caused by microorganism activity. The experimental conditions were 80 mu mol/m2/s light intensity at 25 degrees C under a 16/8 h (D/N) photoperiod. The Arduino-based assembled system contained three subsystems: explant growth, air supplementation, and air sampling and environmental monitoring. The growth vessel had an 83.5% light transmittance with a 3.8 mol/m2/day light intensity. Air ventilation was performed at a flow rate of 1,000 mL/min with 99.9% relative humidity through the filters, which precluded infection and provided a high moisture content environment in the growth vessel during the experiments. A real-time clock library programmed on the development board realized an accurate sampling point and period. The diel gas exchange pattern of pitaya exhibited four phases; explants had a net photosynthetic rate (Pn) of 2.63 mu mol/m2/s at midnight, and the total net CO2 uptake over 24 h was 73.98 mmol/ m2/day. The positive Pn observed during the daytime was noteworthy. This study successfully measured the photosynthetic profile of pitaya in vitro , providing a diel gas exchange reference. An open-flow whole-canopy system could be used in other explants to evaluate the photosynthesis profile in the era of climate change.

High summer temperatures (day/night: 40 °C/30 °C) are known to cause poor fruiting, reduced fruit/seed weight, and delayed fruit development in the “Da Hong” red-fleshed pitaya (Hylocereus polyrhizus); however, the mechanisms of these effects are unknown. This study examined how high temperature (HT, 40 °C/30 °C) affects stamen and pistil fertility through pollination combinations and fruit set in “Da Hong” pitaya and evaluated photosystem II (PSII) efficiency in yellowed shoots (cladodes). The in-vitro pollen germination rate was significantly higher at optimal temperature (OT, 30 °C/20 °C) than at HT, which was also associated with a reduced flower length, poor fruit set, small fruit size, and low number of seeds after self-pollination. Meanwhile, fruit set and fruit development were remarkably improved by using the pollens taken from plants grown at OT and moderate temperature (MH, 35 °C/25 °C) after mutual cross pollination, indicating that the reduction in seed number caused by incomplete fertilization due to inferior pollen viability was the main cause of poor fruiting under HT rather than pistil or photoinhibition, although HT treatment was linked to reductions of PSII efficiency at both the adaxial and abaxial ends of shoots. The results suggested that pollen viability was most affected under HT stress; thus, yielding remarkably reduced fruiting.

Pitaya (Hylocereus spp.) has become a global fruit crop, particularly in Southeast Asia, with two main species cultivated over recent decades; the white-fleshed pitaya (H. undatus) and the red-fleshed pitaya (H. polyrhizus). Although the morphological description of the phenological stages of white-fleshed pitaya (H. undatus) has been recorded using a three-digit numerical system as per the Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scale rule; however, the description of spine development, an important characteristic of bud burst under the areole is lacking. Additionally, the description scale for flesh color change caused by the accumulation of the betalain pigment, which is important for its nutrition value in red-fleshed pitaya, is lacking. This study investigated the phenological stages of a red-fleshed pitaya, an allied species with remarkable similarity to white-fleshed pitaya, “Da Hong” (also called “Big Red”), using the BBCH scale to provide uniform phenology-related information and develop a more suitable scale for the scientific studies and crop practices of red-fleshed pitaya. Furthermore, at each stage, the development of the spine and flesh color to address fruit developmental characteristics owing to its red flesh was simultaneously assessed and recorded. The flesh started to grow at the first stage of fruit development (code 711). The flesh color changed at the final phase of fruit development (code 719) and at the first phase of fruit peel maturity (code 811). The peel color in the flesh and mesocarp changed completely in the final phase (code 819), indicating the completion of fruit maturity. This important phenological stage scale may be used in growth, development, and physiology studies, and in orchard management, including field practice, nutrition management, and pest and disease control.

Micropropagation protocols for red-fleshed Hylocereus species (Cactaceae) have been developed; however, these methods prolong the sprout duration from areoles and produce irregular micro-propagules in ‘Da Hong’ pitaya. Thus, the present study aimed to establish an improved micropropagation protocol for this cultivar. Shoot regeneration and root induction of self-pollinating seedling segments were evaluated in response to combinations of activated charcoal (AC; 200 mg/L), α-naphthaleneacetic acid (NAA; 0.05, 0.10, and 0.20 mg/L), and 6-benzylaminopurine (BAP; 1.00, 2.00, and 4.00 mg/L). The correlations among plantlet growth characteristics and plantlet survival rate after transplantation under field conditions were calculated. Increasing the NAA concentration increased the number of roots but reduced root length. The addition of AC enhanced shoot length and prevented the regeneration of dried-out, clustered, and abnormal shoots. Plantlets treated with 200 mg/L AC and 0.10 mg/L NAA produced the highest number of shoots, i.e., 4.1 shoots, which however, were shorter and lighter than those cultured with AC alone. Plantlets grown on medium supplemented with BAP showed no advantage in shoot number, shoot weight, plantlet surface area, or plantlet volume. The weight and shoot surface area of plantlets were strongly correlated. All plantlets grew well at 4 weeks post-transplantation. Overall, these results support this improved micropropagation method to regenerate robust ex vitro plantlets.

Following high summer temperatures in Taiwan, erratic fruit production and yellowed cladode have been observed in red-fleshed ‘Da Hong’ pitaya (Hylocereus polyrhizus). However, the specific environmental influences that result in the yield loss and cladode damage are unknown. The aim of this study was to evaluate how high temperature affects fruit production and cladode yellowing of ‘Da Hong’ pitaya under controlled conditions. One-year-old field-grown potted plants with moderately yellow-colored cladodes were placed in the phytotron at either 40/30 °C ± 1 °C [day/night, high-temperature treatment (HT)] or 30/20 °C ± 1 °C [day/night, control (CK)] during the natural long-day reproductive period. Floral bud development duration, flower opening behavior, fruit set and development, as well as fruit characteristics and seed setting (which was expressed as the estimated number of seeds), and the weight per fruit at harvest were investigated. In addition, the percentage of dry matter and color change (regreening) of cladodes were examined. We found that floral bud development was completed 8 days earlier than the control, but the time of blooming was 2 to 3 hours later within a day; and fruit set, fruit size, seed weight, and peel color were strongly suppressed in HT-treated plants compared with the control. Furthermore, both the estimated seed number and seed weight were positively correlated with fruit weight, suggesting that reduced seed setting and weight arising from incomplete fertilization in the HT plants may have resulted in fruit drop and smaller fruit. Although the color on the sunny (sun-exposed) side of the cladode remained yellow, the percentage of dry matter in the HT cladodes was not significantly different from the control, indicating that the yellow-colored cladodes did not reduce their carbon supply potential. The results indicate that HT during bloom led to poorer fruit set and lower fruit weight, presumably due to lower seed setting/weight per fruit arising from incomplete fertilization. The HT treatment also caused less regreening of cladodes, but this did not seem to impact fruit production. Further study is required to ascertain whether disrupted stamens or pistils resulting from HT treatment lead to incomplete fertilization.

Night-breaking is used for the off-season production of pitaya (Hylocereus spp.) fruit in subtropical regions but is less successful at higher latitudes with colder winters. Consequently, ambient temperature has been proposed as a crucial factor controlling flowering in pitaya. However, the effects of temperature on reproductive bud development and emergence remain unclear. Therefore, here, we performed two phytotron experiments to clarify these effects in 2-3-year-old field-grown, potted while-fleshed pitaya (Hylocereus undatus "VN White") under an inductive long-day photoperiod (14/10 h) in Taiwan. Experiment I was conducted in late March 2016 and used day/night temperatures of 32/22 degrees C (control) and 23/13 degrees C (low temperature), while experiment II was conducted in late March 2017 and used temperatures of 32/22 degrees C (optimal temperature), 29/19 degrees C (required temperature), and 25/15 degrees C (low temperature). In experiment I, the temperature of the low temperature treatment was increased by 2 degrees C every 4 weeks from the emergence of reproductive buds in the 32/22 degrees C treatment until reproductive bud formation, whereas in experiment II, the temperature of the low temperature treatment was increased to 27/17 degrees C 2 weeks after the first reproductive buds emerged in the 29/19 degrees C treatment. The development (stages 0-3) and the emergence of reproductive and vegetative buds were recorded weekly in all treatment groups. Experiment I showed that temperature had no effect on vegetative bud emergence. However, warm temperatures (32/22 degrees C) enhanced bud development (to stage 3) and induced reproductive bud emergence 3-4 weeks after treatment, whereas most buds remained in a pre-reproductive stage (stage 2) under the low temperature treatment (23/13 degrees C). More buds reached stages 2 and 3 after raising the temperature to 25/15 degrees C, but reproductive buds did not emerge until the temperature reached 29/19 degrees C. Experiment II further showed that plants needed to be kept at 29/19 degrees C for 9 weeks for reproductive bud emergence. Thus, 29/19 degrees C may be the minimum required temperature for reproductive bud emergence, while 32/22 degrees C is the optimal temperature for reproductive bud development and emergence in white-fleshed pitaya. These findings suggest that the induction of reproductive buds in pitaya is first initiated under a long-day photoperiod but warmer temperatures are required for their subsequent emergence.

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.

'Yu Her Pau' is one of the most dominant litchi (Litchi chinensis Sonn.) cultivars grown in Taiwan and China. However, the extremely large inflorescences often result in the production of early- and late- flowering female flowers ("two-sequence inflorescence"), thereby leading to the production of late-maturing fruit within the same cluster. This asynchronous maturity, often being regarded as a nuisance by growers and the impact of this trait requires further clarity. To document the alteration of growth and characteristics of fruits that mature asynchronously inside a cluster, 10-year-old field grown plants were used in the present study. Four categories of fruit early or late-maturing fruit in the presence of single cluster; and early- or late-maturing fruit in the presence of two sequence cluster on trees were selected. The fruit growth curves and patterns, liquid endosperm retention in the embryo sac, primary (apparent) sink strength quantity and harvested quality were analyzed. The accumulated heat unit from fruit set to maturity was estimated. Flowering dates were noted to be three weeks apart, whereas harvest dates were noted to be only one week apart between the early- and late-maturing fruit because of the two-week longer maturity period of the early-maturing fruit. All categories of fruit exhibited single sigmoid curve and have commercial value at harvest, Early-maturing fruit from the early-maturing two-sequence inflorescence were approximately 50% heavier and matured two weeks earlier than the late-maturing fruit and exhibited significantly higher quality. The larger fruit from the early-maturing two-sequence clusters was associated with smaller seeds, higher absolute and relative fruit growth rates, longer fruit development periods in response to lower air temperatures pertaining at that time, greater primary sink strength quantity, longer retention of liquid endosperm, and higher accumulated heat units that were amassed during the pulp growth stage. In the meantime, the earlier dissipating of liquid endosperm in late-maturing fruit and in early-maturing two-sequence fruit was associated with decreased seed size. Late-maturing fruit in two-sequence clusters increased the primary sink strength quantity of early-maturing fruit in the same cluster. The results from our research should prompt a re-assessment of the physiological significance of the second-sequence of female flowers in litchi cultivars with extremely large inflorescence.

The purpose of this study was to determine whether the total number and percentage of female flowers and fruit yield were influenced by the type of inflorescence, i.e., leafless or leafy inflorescences in ‘Yu Her Pau’ litchi ( Litchi chinensis Sonn.). Four 10-year-old field-grown plants in Chunghua, Taiwan, were assessed between March and June 2013. In total, 24 inflorescences comprising 12 each of leafless and leafy inflorescences were investigated. Leaves of the leafy inflorescence, defined as the fourth successive flush, attained maturity before female flower anthesis on 16 Mar. 2013. Shoot diameter and leaf number on the flowering (fruiting) shoot, total number of flowers, and total and percentage of female flowers were recorded. Fruit number, fruit set rate, cluster yield, and fruit quality were also determined at harvest between the two inflorescence types. The two inflorescence types had similar shoot diameters and total leaf number on a flowering shoot. The total number of flowers, female flowers, and the percentage female flowers in leafless inflorescences were 3741, 563, and 16.2%, respectively; these values were 1.3- to 1.7-fold higher ( P ≤ 0.05) than those in leafy inflorescences, which were 2779, 326, and 12.2%, respectively. Leafless inflorescences had significantly higher fruit numbers and fruit yield per cluster at harvest (10.2 and 321.5 g, respectively), although there was no difference ( P > 0.05) in fruit set rate between the two inflorescence types. No fruit quality trait, such as fruit, pericarp, aril, seed weight, aril proportion, and total soluble solid concentration of aril, was significant ( P > 0.05) between the two inflorescence types. We concluded that leafless and leafy inflorescences of ‘Yu Her Pau’ had similar carbon assimilation supply potential; however, leafless inflorescence had greater performance in terms of female flower number and thus fruit yield, presumably due to the absence of assimilate competition brought by synchronous development of lateral inflorescence and immature leaves of panicle.

To accelerate the mulberry breeding program and examine the genome size and ploidy levels of 27 mulberry accessions of promising lines in Taiwan, nuclei suspensions were prepared from unfolded young leaves and analyzed by a flow cytometer. The genome size of each accession was estimated by referring to the standard genome size of chicken erythrocyte nuclei (CEN, 2.5 pg). Our results indicated that 25 among 27 investigated accessions in M. bombycis, M. alba, M. latifolia, M. australis, M. formosnensis, and M. atropurpurea are diploids with genome sizes ranging from 0.61 to 0.71 pg. 'Elongated mulberry No. 1' (M. laevigata) with a genome size of 1.06 pg is a triploid. Two populations were identified in the accession '67C001' (M. australis Poir.) with a genome size of either 0.63 pg or 0.98 pg. Due to their similarity in appearance, we suspected that they are probably from the same origin, thus warranting further investigations. Several important vegetative characters of diploids and triploids have been estimated, including leaf length, leaf width, petiole length, petiole width, leaf thickness, and internode length, to document their correlation using the unpaired t-test. Subsequently, the statistical relationship between diploid and triploid species on some of these important characters, including leaf width, petiole width and internode length, was determined through binary regression analysis. We suggested that the internode length could provide a beneficial index to distinguish individuals with different ploidy levels in the field. Results of this study provide useful information to clarify the taxonomy of Morus and improve breeding programs aiming to advance horticulture and sericulture.

The feasibility of growing 5-year-old "Jen-Ju Ba" guava (Psidium guajava) plants in a fixed field net-house to reduce the amount of shoot and fruit damage caused by typhoons was evaluated in Taiwan in 2013. The field net-house was 2.6-m high and covered with 16-meshes white-net. The plants grown in the field served as the control. Because no typhoon struck Taiwan during the experimental period, only the climate, yield tree(-1) , fruit quality, percentage of matured fruit, and types of pest could be compared. The temperature and humidity were not significantly different between the field net-house and the field, but the 16-mesh net-house shielded 21, 12.5, and 2.5% of the photosynthetic photon flux density (PPFD) relative to the control in summer, autumn, and winter, respectively. The main pests were guava leaf and shoot webber (Spilonota rhothia) and thrips (Rhipiphorothrips cruentatus) in the field and guava mealybug (Planococcus minor) and cotton aphid (Aphis gossypii) in the net-house. However, fruit rot disease was mainly caused by guava scab (Pestalotiopsis psidii) and black spot (Guignardia psidii) in both treatments. The annual yield tree(-1) was higher in the field than in the net-house (87.1 vs. 73.6 kg, respectively) as was the total soluble solids content of fruit in winter, possibly because of the additional shading. However, no other fruit characteristics differed between the two treatments.

Guava is an important fruit crop in Taiwan, but is increasingly affected by drought because of global warming. Therefore, we investigated the effects of two water-withholding/recovery cycles on the physiology and shoot growth of 2-year-old potted guava (Psidium guajava 'Jen-Ju-Bal plants. During the first cycle (days 0-9), leaf water potential (psi leaf) and soil moisture decreased to -1.9 MPa (89% relative water content (RWC)) and -55 kPa (40% RWC), respectively, and the temporary wilting point was reached. Furthermore, the plants exhibited a 28-86% reduction in leaf CO2 exchange rate (Pn), chlorophyll fluorescence under light adaptation (phi PSII), stomatal conductance (Gs), transpiration (E), leaf and soil RWC, psi leaf, and soil moisture compared with well-watered control plants. However, no difference in shoot growth was recorded. During the second cycle (days 13-19), necrotic leaves appeared when psi leaf and soil moisture decreased to -2.9 MPa (81% RWC) and -71 kPa (24% RWC), respectively, and the permanent wilting point was reached. At this stage, the experimental plants exhibited a 16-89% reduction in the abovementioned parameters compared with well-watered control plants and a 20% reduction in growth and a 210% reduction in the relative growth rate of the shoots, suggesting that reductions in Pn and shoot growth were significantly associated with pronounced drying. These findings indicate that an irrigation regime should be developed to optimize the canopy development of guava trees and that Pn, phi PSII, E, and Gs might serve as useful physiological indices of drought.

'Shidareguwa' mulberry (Morus alba var. Shidareguwa) has a graceful weeping canopy that is commonly used in landscaping. However, it has a low rooting ability when conventionally propagated, and a feasible micropropagation system has not yet been reported. This study focused on establishing an in vitro method for plantlet production of 'Shidareguwa' mulberry. Explant types, media, and plant growth regulators (PGRs) were evaluated for their effects on shoot initial culture and multiplication, along with in vitro and ex vitro rooting and survival rate after acclimation and transfer into the field. Shoot tip explants had the highest survival percentage in initial culture. The largest shoot growths were cultured on Murashige and Skoog (MS) medium with 2% sucrose and 4.44 mu M 6-benzylaminopurine (BAP) for 20 days. The best shoot multiplication was achieved using MS medium with 3% sucrose and 4.44 mu M BAP for 30 days. The highest rooting induction (90%) in vitro was achieved using MS medium with 3% sucrose without auxins for 30 days. The well-rooted plantlets obtained in vitro had a 94% survival rate after acclimation. All young shoots from field-grown trees failed to root, but explants from in vitro regenerated shoots showed 100% root induction ex vitro when cultured in same media. These shoots dipped in 2000 ppm IBA exhibited the greatest rooting performance. Ex vitro plants exhibited greater rooting ability, efficiency, and survival after the first acclimation than in vitro plants. We present a novel and feasible method of plantlet production through in vitro propagation of shoot tips. (C) 2015 Elsevier B.V. All rights reserved.

Improving berry skin coloration is one of the major challenges in the tropical and subtropical viticulture. In this paper we aimed to document the effects of girdling at veraison on berry coloration and quality in grapevines on different rootstocks and we assessed the seasonal variations of girdling effects in the subtropical double cropping system. In the first experiment, girdling at veraison was tested in 'Kyoho' on 5C rootstocks. In the second experiment, own-rooted 'Kyoho', 5C or 1202C rootstocks were compared. Vines were trained to a horizontal overhead trellis with a single trunk and two short arms. One arm of each vine was girdled at veraison and the other arm served as the control. Girdling at veraison significantly improved skin color of berries from own-rooted vines or 5C rootstocks in the summer cropping cycle but was less effective in the winter cropping cycle. Girdling improved total soluble solids in own-rooted vines in the summer cropping cycle and in vines on 1202C in the winter cropping cycle. Girdling made in the winter cropping cycle did not completely heal until post-bloom in the following spring and reduced length of the fruiting shoot, number of leaves per shoot, and length of inflorescences of the next summer cropping cycle. We concluded that girdling at veraison is a good practice to improve berry color and quality for the summer cropping cycle but is not recommended for the winter cropping cycle.

In this study, we documented whether pollen parents are required for fruiting and their effects on fruit set and seed characteristics in field-grown '73-S-20' litchi (Litchi chinensis Sonn.). The effects of preventing female (F) flower pollination to induce parthenocarpy, selfing, and outcrossing with 'Haak Yip' and open-pollinated (OP) fruits derived from F flowers and the second wave of the male (M-2) flowers of 'Haak Yip' blooming in synchrony were assessed. The correlation between the percentage of fruit set and shriveled seed/seed weight in self-crossed and outcrossed fruits was calculated. At harvest, the absence of pollination induced a high proportion of parthenocarpic fruit without seed, although the fruit weighed only 4.2 g. Fruit set with outcrossing was greater than that with selfing and the percentage of shriveled seed obtained in self-crossed fruits was much greater than that in outcrossed fruits but not different from that in OP fruits, suggesting that outcrossing increased but selfing decreased the cluster yield and seed weight. However, 33.3% and 23.0% of seed contained embryos in selfed and OP fruits, respectively. No positive correlation between the percentage of fruit set and shriveled seed/seed weight was found, indicating that seed abortion during development was not the key factor leading to low yield. We concluded that tiny parthenocarpic fruit could be obtained but that pollination is essential for the good yield of '73-S-20'. Outcrossing markedly increased fruit set and seed weight and decreased the percentage of shriveled seed. Factors other than the pollen parents may be involved in the seed development of '73-S-20'.

'Shiaying' mulberry (Morus atropurpurea Roxb.) is a promising cultivar for berry production in Taiwan. 'Shiaying' produces plentiful and attractive dark purple, glossy berries. Compared with the three most commercially available mulberry cultivars in Shiaying, Tainan (southern Taiwan), i.e. 'Taisang No. 19' (Mona atropurpurea Roxb.), 'Miaoli No. 1' (Morus atropurpurea Roxb.), and 'Elongated Fruit No. 1' (Morus laevigata Wall), the average berry weight (5.8 g) of 'Shiaying' was similar to that of 'Miaoli No.1' and 'Elongated Fruit No. 1', but significantly heavier than that of 'Taisang No. 19'. The yield of 'Shiaying' (19.5 kg/tree) was as abundant as the yields of 'Taisang No. 19' and 'Miaoli No. 1' but was much higher than that of 'Elongated Fruit No. 1'. Additionally, the fruit of 'Shiaying' ripened 5-20 days later than the fruits of the three comparable cultivars. 'Shiaying' fruit also has a much higher soluble solids concentration, SSC (14.0%), and the quality of the berry, in terms of taste, is superior to that of both 'Taisang No. 19' and 'Miaoli No. 1'. This particular cultivar is recommended for multiple uses in the horticultural and food industries and is very suitable for both fresh consumption and the processing market in Taiwan.

•Vegetative traits and chilling requirements were used to classify Morus spp. into 3 major taxonomic groups in Taiwan.•A new unbiased key to Morus spp. with variable sex expression patterns was established based on 9 representative traits.•M. atropurpurea in Taiwan might have evolved independently from related species in other areas.•An indigenous species, M. formosensis, may be derived from M. australis.

Leaf age and light intensity dramatically affect the leaf photosynthetic capacity of the developing canopy of erect herbaceous plants. However, little is known regarding this response in papaya trees. The objective of this study was to determine how leaf age and light intensity affect the gas exchange characteristics within a developing papaya canopy by examining the distribution of maximum net CO2 assimilation in saturated light (A(CO2)) and photosynthetic photo flux density (PPFD) of papaya trees cultivated in a field net-house. To measure changes in relative gas exchange capacity with leaf age, a comparison of the gas exchange parameters of individual tagged leaves and the leaf position with maximum A(CO2) within the developing canopy was carried out at a leaf age between 14 and 98 days in two cropping seasons (2008-2009 and 2009-2010). At or before the time of full leaf expansion (leaf age 26-36 days), the total chlorophyll concentration, relative A(CO2), transpiration rate (E), stomatal conductance (g(s)) and PPFD reached maximum levels. In leaves aged 26-62 days, the relative A(CO2) remained at above 90% of the maximum A(CO2) and above 60% of PPFD. As the leaves aged and gradually became over-shaded within the canopy, the relative A(CO2) gradually declined to 45-55% of the maximum. The degree of decline in gs was larger than that in A(CO2) and E, but no significant differences were observed in C-i among the various leaf ages. Therefore, our results imply that A(CO2) was limited by coordinated changes in both stomatal and nonstomatal factors. To access the photosynthetic capacity and light intensity profile in the papaya canopy, we investigated the A(CO2) and PPFD at each leaf position within the canopy near time of harvest. The observed high extinction coefficient value (1.68) for field net-house-grown papaya at a high solar elevation indicated that the mature leaves in the top layer did not cover each other in the upper strata but effectively shaded leaves in the lower strata. The mature leaves in the upper layer of the canopy with a LAI of 0.3-1.4 m(2) m(-2) (46% of the total leaf area of the canopy) were able to maintain high PPFD and A(CO2). The study suggests that an ideal papaya canopy should be exposed to a LAI of 0.3-1.4m(2) m(-2) (approximately the 11th-29th leaf position) to acquire the maximum amount of PPFD and maintain photosynthetic capacity during mid-day measurements near harvest. (C) 2013 Elsevier B.V. All rights reserved.