Inheritance Study of Heat Tolerance in Sweet Peppers (Capsicum annuum L.)

• Main Authors: Sheue-Chin Shieh, 謝雪琴
• Other Authors: Dr. Ching-Hsiang Hsieh
• Format: Others
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/32835104185598428296

碩士 === 國立屏東科技大學 === 熱帶農業暨國際合作系 === 102 === The growth of sweet pepper (Capsicum annuum L.) is constrained by numerous abiotic (temperatures, humidity, light, etc.) and biotic (disease, insect, plant, etc.) factors. Heat stress is one of the most important factors to affect the sweet pepper production. Field trials were conducted for 16 sweet pepper germplasms in summer 2010 and fall 2010-2011. The summer yield trial showed higher variance (σ2g) and broad sense hereditability (Hb) than the fall trial which suggested better selection potential in summer. The heat tolerant line 9848-4840 and susceptible line 0436-6005 were selected as parents based on the summer yield as percentage of fall yield for inheritance study. Generations mean analysis (GMA) of the cross CCA8979 ( P1, P2, F1, F2, BCP1 and BCP2) was conducted under heat condition (summer, 2011). The Joint Scaling Test showed significant positive additive gene effect for all the test traits except for fruit weight. The epistasis, non-allelic gene effects were also involved in all traits. Significant additive ＊ additive gene effects were found on fruit number, fruit weight and yield; additive ＊ dominance effects on fruit weight and plant height, and dominance ＊ dominance effect on fruit number and plant height were also detected. The narrow sense heritability and broad sense heritability for yield were 0.51 and 0.59 respectively which indicated that about 50% potential of heat tolerant genes could be selected under these conditions. The results suggested that sweet pepper breeding strategy for improving yield and yield related components under heat stress can be based on pedigree method or recurrent selection. In vitro pollen germination and tube growth were tested under wide temperatures regimes (27-40oC) for the 16 germplasms. The result showed pollen germination and tube growth were significantly reduced under 36 - 40oC temperatures. The pollen germination and pollen tube elongation at 36oC incubation showed highest variance and broad sense heritability in both seasons. It is suggested that 36oC is the critical temperature to differentiate the heat tolerant and heat susceptible lines. Eight of sixteen lines showed consistent with high pollen viability at 36-40oC, and seven lines were fair on yield. This suggests that it would be valid to develop a good screen method by testing the pollen viability at high temperatures. Root studies were measured at four stages of the 16 pepper germplasms. Significantly high correlations (0.5179-0.8940; P < 0.01)) between plant and root parts were found at every stage. Lower correlations between fruit and root parts (0.1334-0.6919; P < 0.01) were also found. At stage 3, 88 days after transplanting (DAT) and stage 4 (110 DAT), the correlations between plant with roots and between total plant with roots showed 0.7-0.9. This study suggested that the above ground parts are significantly correlated with the roots parts. According to the tested data, the use of regression to predict the root development from the plant and fruit growth could be feasible.