No abstract

The in vitro culture of unpollinated ovaries is one of the techniques used to induce gynogenesis. To explore the mechanism of lily gynogenesis and obtain haploids to shorten the breeding cycle, the in vitro effects of flower bud sampling time, exogenous plant growth regulators (PGRs), and different concentrations of picloram on embryo formation in unpollinated ovaries of Lilium L. 'Sorbonne' (oriental hybrids) were studied. The results indicated that flower buds ≥8 cm in length were most suitable. The PGRs picloram and 2,4-dichlorophenoxyacetic acid (2,4-D) with 6benzylaminopurine (6-BA) or kinetin were useful in inducing ovule expansion in vitro. However, most ovules did not survive on the media containing 2,4-D, whereas those grown on media containing picloram developed normally. In particular, a lower concentration of picloram (0.5 mg L −1 ) was found to be beneficial to the development of ovules into embryogenic shoots, whereas higher concentrations were more favorable to the development of shoots from the ovary wall. In total, 87 regenerated plants were obtained from unpollinated ovaries of Sorbonne. The chromosome ploidy of 20 of these was determined by counting root tip chromosomes, and eight of the regenerated plants were found to be haploids.

Using the tobacco variety Yunyan87 as an example, we investigated the effects of the combined application of organic fertilizer and microbial agents on the physicochemical properties and enzyme activities of tobacco soil and on tobacco agronomic parameters. Compared with the control group, the contents of alkali-hydrolyzed nitrogen, available potassium, and available phosphorus in the soil treated with organic fertilizer and microbial agents increased by 27.7, 12.3, and 133.7%, respectively. The activities of soil urease, phosphatase, sucrase, and catalase increased by 86.3, 85.1, 46.6, and 33.5%, respectively, while the numbers of bacteria and actinobacteria increased by 89.9 and 183.4% respectively. In contrast, the numbers of fungi decreased by 64.8%. Plant height, effective leaf number, stem circumference, stalk width, cutting length, and cutting width increased by 8.1, 7.8, 12.1, 15.7, 20.5, and 11.5%, respectively. Based on our results, the application of organic fertilizer combined with microbial agents significantly improved soil properties, enzyme activities, microbial numbers, and tobacco agronomic parameters.