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- Author or Editor: Huey-Ling Lin x
Passion fruit is a commercial crop of economic importance worldwide, with recent increases in demand for high-quality plants for commercial production. Plant tissue culture is widely used for the mass propagation of many commercial crops, however its application on passion fruit is challenged by the problem of low reproducibility, leaf chlorosis, and growth retardation resulted from in vitro culture. The aim of this study was to evaluate the effects of cytokinins and light quality on in vitro culture of nodal segments of passion fruit ‘Tainung No. 1’. Three aromatic cytokinins were tested in a modified MS basal medium. The bud proliferation rates of segments initiated on a media containing 1 mg·L−1 meta-topolin riboside (mTR) or benzyladenine (BA) were not significantly different at the same concentration. Buds cultured on medium supplemented with mTR grew and elongated for 4 weeks, while buds on a medium containing BA formed rosettes. After transfer to a medium without plant growth regulators (PGRs), shoots rooted spontaneously within 8 weeks. Furthermore, the effects of continuous propagation under a high proportion of red light affected the subsequent plant growth. Red LED induced an increase in the chlorophyll content (2.71 mg·g−1) compared with other light qualities (1.05–2.63 mg·g−1) and improved plantlet quality. Acclimated plants were grown in the field, and the flower morphology and fruit set were of commercial quality. Findings showed that replacing BA with mTR as the main cytokinin and using a high proportion of red light during the tissue culture induction period produced high-quality plantlets in 3 months. This system is economical and will be further developed for the commercial propagation of passion fruit vines in the future.
The king oyster mushroom [Pleurotus eryngii (DC.:Fr.) Quél.] is gaining popularity across the world due to its excellent taste, high nutritional quality, medicinal value, and long shelf life. Conventional substrates for king oyster mushroom cultivation consist of sawdust derived from various tree species. Sawdust demand is increasing worldwide, creating a need for alternative materials that can at least partially replace sawdust as substrate for king oyster mushroom. In Taiwan, as in other countries that grow fruit trees, pruned fruit tree branches are an expensive agricultural waste, particularly if they are not recycled or reused. In the present study, we evaluated substrates containing sawdust and different proportions of material ground from pruned wax apple or Indian jujube branches for cultivation of king oyster mushroom. Our results suggested that among all five substrate mixes tested, the best substitute for conventional sawdust (100% sawdust) was a substrate that contained 75% sawdust mixed with 25% materials ground from trimmed wax apple branches (Wax apple 25%). Furthermore, determination of mineral element content, pH, and electrical conductivity (EC) levels of the substrates both before spawn inoculation and after harvesting revealed no significant changes in mineral content, a slight reduction in pH value, and a minor increase in EC levels after cultivation. Taken together, results from this study suggest that agricultural wastes from pruned fruit tree branches can partially replace sawdust as the cultivation substrate for king oyster mushroom.
Smoke-water is a chemical extract used to stimulate the germination of many plant species under cultivation. This study evaluated the efficacy of smoke-water on the seed germination and seedling growth of papaya (Carica papaya cv. Tainung No. 2). Smoke-water, prepared from dry rice straw (Oryza sativa) by burning and bubbling the smoke through water, was used for germination experiments, growth experiments, and anatomical structure changes of seeds. In the germination experiments, papaya seeds were soaked with different concentrations of smoke-water (0.1%, 0.2%, 1%, 2%, 3%, 4%, 5%, 7%, or 10%, v/v) for 24 h before planting. Low concentrations of smoke-water (0.1% or 0.2%, v/v) not only promoted the maximum rate of germination, but also shortened the germination time. Analysis of longitudinal sections of seeds treated with smoke-water concentrations of 0.1% or 0.2% v/v suggested that smoke-water could overcome water impermeability barriers, because it stimulated the seedcoat to rupture and allowed the radical to elongate and emerge faster. In the growth experiments, papaya seedlings were transplanted into peatmoss-filled pots that were saturated with different concentrations of smoke-water (0%, 1%, 2%, 3%, 4%, 5%, 7%, or 10%, v/v). Results showed that all growth parameters increased significantly compared with the control. In addition, smoke-water treatments consistently and significantly increased the percentage of nitrogen in roots and shoots and significantly increased the percentage of magnesium in shoots. In these experiments, smoke-water showed potent germination promotion at low concentrations and promoted multiple growth attributes such as chlorophyll content and seedling vigor index at all concentrations in papaya seedling production.
Papaya milk, a mixture of papaya pulp and dairy milk, is one of the most popular beverages in Taiwan. However, the enzymes present in papaya can cause accumulation of hydrophobic amino acids, resulting in a bitter taste of papaya milk. Thus, it is important to select papaya cultivars without the potential to form the bitter taste, but it is difficult to select these papaya cultivars using a sensory test. The purpose of this research was to investigate the relationship between the intensity of the bitterness with the contents of proteins and free amino acids. The results indicated that neither milk nor papaya alone tastes bitter. Heating the milk or the papaya before mixing and mixing only papaya latex with milk confirmed that an enzyme in papaya causes the bitter taste in papaya milk. The intensity of bitterness positively correlated with the contents of total soluble protein, free amino acids and the phenylalanine and tyrosine/tryptophan contents. Analyses using different papaya accessions in different seasons showed that tyrosine/tryptophan (r = 0.613***) and phenylalanine (r = 0.612***) correlate more strongly with bitterness intensity than the total soluble protein (r = 0.258*) or free amino acids (r = 0.38**). In this drink, milk provides the substrates to form the bitter substances, but the enzymes in the papaya are needed for the reaction to occur. The levels of the amino acids phenylalanine and tyrosine/tryptophan showed the highest correlation with the intensity of bitterness.
Global surface temperatures are predicted to increase by 1 to 4 °C by the year 2100. To unravel the risks from rising temperature to Taiwan’s summer leafy vegetable production, the phenotypical and physiological responses of two leafy crops, pak choi (Brassica chinensis L. cv. Quanzhou) and edible amaranth (Amaranthus tricolor L. cv. White leaf), were compared under an elevated temperature. A temperature increase from 28 to 32 °C resulted in lower leaf calcium, magnesium, and manganese concentrations (dry weight basis) in pak choi without significant changes in shoot dry weight, suggesting potential negative effects of the elevated temperature on pak choi leaf nutrient status. However, increased temperature promoted both root and leaf growth in edible amaranth, which may be beneficial to its yield, making edible amaranth a potential summer leafy vegetable crop for Taiwan. Furthermore, a temperature change from 28 to 32 °C resulted in a higher leaf nitrate concentration in edible amaranth, because of the lower nitrate reductase activity (NRA). Thus, suitable nitrogen fertilization rates and programs under elevated temperature conditions should be reconsidered in the future. To sum up, a future rise in summer temperatures may impose negative impacts on pak choi leaf nutrient status but positive impacts on edible amaranth production.
The volatile profile of the edible vegetable Gynura bicolor [Gynura bicolor (Roxb. ex Willd.) DC] was analyzed using gas chromatography-mass spectrometry (GC-MS). Isocaryophyllene (23.2%), α-pinene (16.8%), α-humulene (9.1%), β-pinene (7.3%), and copaene (7.0%) were identified as the major compounds in the leaves. In the stems, α-pinene (27.1%), β-pinene (13.0%), isocaryophyllene (7.8%), β-myrceneb (7.8%), 1-undecene (5.7%), and copaene (5.3%) were the main components. G. bicolor grows best at 25 °C. When cultivated at different temperatures (20 to 35 °C in incements of 5 °C), the volatile profiles shifted. The proportion of isocaryophyllene was lower at 20 °C than at the other temperatures. The relative amounts of α-pinene and α-humulene were highest at 20 °C, whereas copaene was highest at 35 °C. Principal component analysis (PCA) was used to explore the correlation between volatile compounds identified from the vegetative tissues and temperature treatments. It reveals the same trend with the previous statements and the first principal component (PC1) and the second principal component (PC2) explains up to 90% of the variance. Experimental results revealed that both temperature and vegetative organ correlate with the volatile emission profile of G. bicolor.
The antifungal efficacy of smoke-water on damping-off caused by Pythium sp. was evaluated both in vitro and in vivo. Smoke-water was generated by burning plant material and bubbling the smoke through water; its effect on the morphology of Pythium sp. was investigated by scanning electron microscope (SEM). Mycelia growth and oospore production of the fungus were significantly inhibited when cultured on water agar amended with smoke-water at 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%. In growth chamber experiments with potted seedlings growing in peatmoss, papaya plants treated with smoke-water exhibited reduced symptoms of damping-off when compared with control plants treated with water. Furthermore, the pots treated with 1.5% or higher smoke-water did not show any symptoms of damping-off disease. Plant height significantly increased with treatment by higher concentrations of smoke-water. Maximum plant height was observed with treatment of 1% smoke-water or higher concentrations. One day after smoke-water application, SEM observations of the Pythium sp. revealed loss of structural integrity, abnormal degradation, deformation, abnormal lysis, cytoplasmic leakage, and hyphal slimming. This study showed that the addition of smoke-water to soil exerted significant disease suppression against Pythium sp., leading to improved growth of papaya seedlings.
A xylem mutant (vse) was isolated from a Bambusa edulis (Odashima) Keng plantlet following vegetative micropropagation and subculture for 7 consecutive years and induced to proliferate in medium supplemented with 0.1 mg·L-1 (0.5 μm) thidiazuron (TDZ) and to develop roots in medium supplemented with 5 mg·L-1 (26.9 μm) α-naphthaleneacetic acid (NAA). Subsequent investigations comparing the growth habits of mutant plantlets with those of the wild type indicated that the growth of the former was retarded in a greenhouse. Several morphological abnormalities were observed in the vse mutant: it had thinner stems with fewer trichromes on the surface; the xylem vessels were smaller in diameter and contained crystal-like structures in the pith; the leaves were shorter and narrower with a sharp leaf blade angle; the roots were thinner and contained fewer xylem cells. The cation concentrations of both the mutant and wild type were similar in the in vitro analysis, except for those of iron and potassium, which were lower in mutant leaves in vivo. In 2-month-old mutant plants, iron chlorosis was observed on young leaves and a potassium deficiency was observed on older leaves. After 1 year of growth in the greenhouse, all of the wild-type plants had survived, but only 27% (16/60) of the mutant vse plants were alive.