Abstract:【Objective】To study the pollen viability and stigma receptivity of 25 species (including 8 local varieties, 15 introduced varieties/strains, and 2 selected varieties/strains.) of Passiflora L., and provide theoretical basis for the selection of crossing parents of Passiflora L.【Methods】Using six representative species of Passiflora L. as test materials, including TN, HX No.1, GH, W-1, XG and KSTS a single-factor experiment was conducted using a basic medium containing 0.02% boric acid (H3BO3), 15% sucrose, 15% PEG-4000, 0.08% calcium nitrate [Ca(NO3)2·4H2O], and 0.02% MgSO4·7H2O. The aim was to screen for the optimal concentrations of sucrose, boric acid, PEG-4000, calcium nitrate, and incubation temperature. Using 25 species of Passiflora L. including TN, HX No. 1, W-1, XG, XTN, QM No. 9, MGMX, LP, QP, FMHJ, HG, YYM, ZZ-B1, D1-A1, THX, ZXMB, D2-11, II-Y, ULGRQG, GH, KSTS, JMCH, RX, ZL and LX as test materials, basic floral morphological parameters were measured using methods such as microscopy and vernier caliper. Pollen vitality was detected using pollen vitro-culture, TTC staining, and I2-KI staining methods to compare and analyze differences in pollen vitality among different detection methods and species. Additionally, the stigmatic receptivity of the 25 species of Passiflora L. was compared and analyzed using the benzidine-hydrogen peroxide method.【Results】The results showed that, the all 25 species of Passiflora L. exhibited stigma receptivity, but there were differences in receptivity among them. Specifically, 19 species, including TN, HX No. 1, W-1, XG, XTN, QM No. 9, MGMX, LP, QP, FMHJ, HG, YYM, ZZ-B1, D1-A1, THX, ZXMB, D2-11, II-Y and ULGRQG exhibited strong stigma receptivity. Three species, GH, KSTS and JMCH had moderate stigma receptivity, while another three species, RX, ZL and LX showed weaker stigma receptivity. Among the six representative species of Passiflora L. including TN, HX No.1, W-1, KSTS, XG and GH only the optimal sucrose concentration differed in pollen vitro-culture conditions. The optimal concentrations of boric acid, PEG-4000, and calcium nitrate were 0.02%, 15%, and 0.08%, respectively, with an optimal incubation temperature of 25°C. Among these species, the optimal sucrose concentration for TN, HX No. 1, GH and KSTS was 15%, while the optimal sucrose concentration for W-1 and XG was 10%. Three detection methods for pollen vitality, including pollen vitro-culture, TTC staining, and I2-KI staining, were used to compare and analyze the pollen vitality of 25 species of Passiflora L. Although all three methods were able to detect the pollen vitality of Passiflora L., there were significant differences among them. Among these methods, pollen vitro-culture was the most effective for demonstrating the pollen vitality of the 25 species, followed by TTC staining, which could serve as a rapid detection method. However, the results obtained using I2-KI staining differed significantly from the other two methods and were not suitable for detecting the pollen vitality of Passiflora L. Based on pollen vitro-culture and TTC staining methods, a cluster analysis was conducted to classify the 25 species of Passiflora L. into three groups. Group I consisted of 21 species, including FMHJ, ZXMB, W-1, II-Y, LP, XTN, TN, THX, QM No.9, ULGRQG, HX No.1, D1-A1, D2-11, YYM, XG, MGMX, QP, HG, ZZ-B1, KSTS and JMCH with pollen vitality above 70%, considered as normally fertile. Group II consisted of only one species, GH with pollen vitality between 50% and 70%, also considered as normally fertile. Group III included three species, ZL, LX and RX which belonged to the high sterile category.【Conclusion】Among the three detection methods, pollen vitro-culture is the most effective for evaluating the pollen vitality of the 25 species of Passiflora L., while the TTC staining method can serve as a rapid alternative. Among the 25 species (varieties) of Passiflora L., ZL, LX and RX are suitable as female parents for hybridization, while the remaining 22 species including FMHJ, ZXMB, W-1, II-Y, LP, XTN, TN, THX, QM No.9, ULGRQG, HX No.1, D1-A1, D2-11, YYM, XG, MGMX, QP, HG, ZZ-B1, KSTS, JMCH and GH can be used as either male or female parents for hybridization.
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