Study on Water-Stress Tolerance in Bedding Plants

• Main Authors: Jia-Hua Hung, 洪嘉樺
• Other Authors: Der-Ming Yeh
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/78319381010662803811

碩士 === 國立臺灣大學 === 園藝學研究所 === 102 === Bedding plants are widely used in urban landscaping, but urban condtions easily cause drought and flooding stress to the plants. In this research, several common bedding plant species and cultivars in Taiwan were grown under different substrate volumetric water content (VWC) treatments, plant growth, quality, and photosynthesis parameters were measured to have a better understanding of their drought- or moisture-tolerability. In this research, bedding plant were grown under 65% and 70% VWC moisture treatment, 40% VWC treatment, 20% VWC drought treatment, and 20/70% VWC drought and rewater treatment. Result showed that, all tested plant species and cultivars grown best under 40% VWC, rather than commonly practice of 20/70% VWC treatment, which could maintain plant compact and flowering and performed desirable plant quality. Amoung the summer bedding plant species and cultivars tested, Torenia fournieri Lind. ‘Clown Blue and White’ under 20% VWC had the lowest net photosynthesis rate (Pn), leaf number, branch number, shoot dry weight (SDW) and root dry weight (RDW), and exhibited leaf chlorosis and leaf drop, Torenia had best growth and performance and the highest Pn under 65% VWC treatment, Angelonia salicariifolia Humb. &; Bonpl. ‘Serena Lavender Pink’ and Ruellia brittoniana Leonard ‘Emerald Pink’ under various VWC treatments had similar performances to Torenia, thus Torenia, Angelonia and Ruellia were categorized as drought-susceptible and moisture-tolerant species. Pentas lanceolata (Forsk.) Schum ‘Skystar Deep Rose’ had the lowest leaf number, branch number, and SDW when grown under 20% VWC treatment, but had the highest leaf and branch number and SDW under 40% and 65% VWC treatment. However Pn of Pentas did not decrease significantly under 20% VWC treatment, and therefore could be categorized as moisture-loving species. Celosia cristata L. ‘New Look Red’ grown under 70% VWC treatment had wilted inflorescences and leaves, and decreased leaf number, and lead to poor plant quality. Moisture caused decreased Pn mainly due to stomatal limitation. Leave did not express stress symptoms when grown under 20% VWC treatment, and Pn under 20% VWC did not differ to 40% VWC treatement Thus Celosia was categorized as drought-tolerant and moisture-susceptible species. Melampodium paludosum (Pers) DC. ‘Million Gold’ had the lowest flower and branch number, SDW, and Pn when grown under 20% and 70% VWC treatments, and therefore Melampodium was categorized as drought and moisture-susceptible species. Leaf number, SDW, RDW, and plant quality of Solenostemon scutellarioides (L.) Codd. ‘Green Cloud’ were highest under 70% VWC treatments, and lowest under 20% VWC treatment. However, there was had no obvious stress symptom dspite that the plants were smaller under 20% VWC treatment. Therefore Solenostemon was categorized as drought-tolerant and moisture-loving species. Gomphrena globosa L. ‘Buddy Purple’ had the lowest SDW, and plant quality, and lower leaf chlorosis, leaf drop when grown under 70% VWC treatment. Pn was drcreased due to both stomatal and non-stomatal limitation. Gomphrena grown under 20% VWC and 40% VWC treatments did not different in leaf number, SDW, and Pn, Thus Gomphrena was categorized as drought -tolerant and moisture-susceptible species. Except ‘Mediterranean Rose Halo’, six cultivars of Catharanthus roseus (L.) G. Don had the lowest flower number, flower diameter, plant quality, and leaf chlorosis and leaf drop under 70% VWC treatment. All plants grown under 20% VWC treatment maintained flowering and deep green color leaf, with good plant quality, thus Catharanthus was categorized as drought-tolerant and moisture-susceptible species. ‘Mediterranean Rose Halo’ maintained flowering, with less leaf drop, and good plant quality when grown under 70% VWC treatment, suggesting that ‘Mediterranean Rose Halo’ might be a moisture-tolerant Catharanthus cultivar. For the winter and spring bedding plant species tested, Petunia ×hybrida Hort. ex E. Vilm. ‘Daddy Red’ and ‘Eagle Blue’ both had the lowest leaf, flower, and branch number, Pn, and poor plant quality when grown under 70% VWC treatment. Petunias maintained flowering and plant quality under 20% VWC treatment though the plants were smaller. Thus, Petunia was categorized as moisture-susceptible species. Leaf, and flower number, SDW, plant quality, and Pn of Impatiens walleriana Hook. f. ‘Accent Rose’ and ‘Candy Rose’ were lowest when grown under 20% VWC treatment and highest under 70% VWC treatment. Therefore, Impatiens was categorized as drought-susceptible and moisture-loving species. Begonia semperflorens-cultorum hort. ‘Party Scarlet’ had similar performance between 20% and 70% VWC treatments, but plants had light green leaves, with lower quality under 20% VWC. Leaf and flower number, and SDW of Begonia ‘Super Olympia Red’ were higher under 70% VWC than 20% VWC treatment. Begonia was categorized as drought-tolerant and moisture-tolerant species. ‘Super Olympia Red’ had higher moisture-tolerance than ‘Party Scarlet’. Salvia splendens Ker-Grawl. ‘Vista Red’ and Salvia farinacea Benth. ‘Victoria Blue’ under 70% VWC had wilted leaves and inflorescences and poor plant quality, and thus Salvia was categorized as moisture-susceptible species. Leaf number and flower number, SDW of Dianthus hybrida ‘Super Parfait Strawberry’ did not differ amount various VWC treatments. However, plants under 70% VWC had leaf chlorosis and wilting in lower leaves, and thus Dianthus was categorized as drought-tolerant and moisture- susceptible species. Lobelia erinus Thunb. ‘Riviera Mix’ had the lowest flower number, flower diameter, branch number, and SDW when grown under 20% VWC treatment, but had the best performance under 70% VWC treatment. Therefore Lobelia was categorized as drought-susceptible and moisture-loving species. Under 70% VWC treatments resulted in decreased leaf and flower number of Tagetes erecta L. ‘Inca Yellow’ and Tagetes patula L. ‘Safari Yellow’. Tagetes was therefore categorized as moisture -susceptible species. Pelargonium hortorum Bailey ‘Multibloom Scarlet’ had the lowest leaf and branch number, SDW, and Pn when grown under 70% VWC treatment. In contrast, although smaller, plants maintained flowering and quality, with no sign of drought stress when grown under 20% VWC treatment, Thus Pelargonium was categorized as drought-tolerant and moisture-susceptible species. Senecio cineraria DC. ‘Silverado’ had the highest leaf number, SDW, and plant quality when grown under 70% VWC treatment. Plants under 20% VWC were smaller, had fewer leaves and branches, but remained good quality without any sign of drought stress. Thus Senecio was categorized as drought-tolerant and moisture-loving species.