Screening commercial African violet cultivars for high temperature tolerance using physiological and pollen parameters

• Main Authors: To Nhhu Ai, 涂如愛
• Other Authors: Fang Jong-Yi
• Format: Others
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/16213900986301379511

碩士 === 國立屏東科技大學 === 熱帶農業暨國際合作系 === 101 === Abstract Student ID: 9922018 Title of Thesis: Screening commercial African violet cultivars for high temperature tolerance using physiological and pollen parameters Total Pages: 105 Name of Institute: Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology Graduate Date: January 18, 2013 Degree Conferred: Master Degree Name of Student: To, Nhu Ai Advisor: Fang Jong-Yi The Contents of Abstract in This Thesis: The increase of temperature may be inevitable in the future because of rising greenhouse gases emission into the air. Continuous search and/or breeding of heat tolerant cultivars will be important for the sustainability of plant germplasm. For this, it is essential to identify heat tolerant germplasms in order to incorporate them into breeding programs for the creation of cultivars which contain heat tolerant traits. Hence, this study was conducted with the objective to screen and identify for heat tolerant cultivars among thirty commercial African violet entries. The evaluation of heat tolerance in African violets will be conducted by studying both physiological and pollen parameters under different temperature treatments. Cell membrane thermo-stability (CMT) and canopy temperature depression (CTD) and chlorophyll stability index (CSI) were determined using fully expanded leaves. In vitro pollen germination percentage and pollen tube length were estimated at a temperature range between 10 and 40oC. Cardinal temperatures (Tmin, Topt, and Tmax) of pollen germination (PG) and pollen tube length (PTL) as well as maximum pollen germination percentage (PGmax) and maximum pollen tube length (PTLmax) were estimated by using the modified bilinear model. Results showed that the different cultivars differed in terms of the three physiological parameters. Results showed that the different cultivars differed in terms of the three physiological parameters. The values of cell membrane thermostability (CMT), canopy temperature depression (CTD) and chlorophyll stability index (CSI) ranged between 5.39 to 74.07%, -1.65 to 0.61oC, and 70.16 to 81.06%, respectively. They also varied significantly for pollen germination percentage (PG) (mean of 54.43%), pollen tube length (PTL) (mean of 3109.08µm), cardinal temperatures (Tmin = -4.63, Topt = 24.90 and Tmax = 49.93oC for PG; and Tmin = 3.38, Topt = 25.98, and Tmax = 43.11oC for PTL). Based on cumulative temperature response index (CTRI), the 30 African violet cultivars were classified into three groups. The cultivars were considered as heat-tolerant when their CTRI was higher than 5.8, intermediate when their CTRI ranged from 3.8-5.8, and heat-sensitive cultivars when their CTRI was lower than 3.8. In total, 14 cultivars were classified as heat tolerant, 11 as intermediate and 5 as heat sensitive cultivars. Continuous use of the combination of pollen and physiological parameters would allow more heat tolerant cultivars of African violets to be identified and new heat tolerant lines to be produced. Keywords: heat tolerance, cell membrane thermostability, canopy temperature depression, chlorophyll stability index, African violet, pollen germination, pollen tube length, individual stress-response index, cumulative temperature response index.