Effects of Different Sample Parts and Sterilization Methods on Contamination and Survival Rates of Shoots with Buds in Chinese Chestnut

In this study,we investigated the preferable explant types and sterilization method for tissue culture in Chinese chestnut,in order to provide a technical support for the asexual reproduction of Chinese chestnut.The base,middle and apex parts of annual shoots with buds in Chinese chestnut were sampled and cut to 2-3 cm stem segments each with one bud,then sterilized orderly with different duration in 2%NaClO plus 0.1%HgCl_(2)solutions.The results indicated that the duration of 2%NaClO for 20 min+0.1%HgCl_(2)for 15 min exerted an effective disinfection property on the middle parts of annual shoots with buds,and achieved a contamination rate under 5%and a survival rate over 90%.

Study on Surface Sterilization Method for Tissue Culture of Haloxylon ammodendron(C.A.Mey.) Bunge Seeds

[ Objective ] The aim was to select appropriate sterilization methods and explants for tissue culture of Haloxylon ammodendron （ C. A. Mey. ）. [Method] H. ammodendron （C. A. Mey. ） seeds were used as experimental materials to investigate the sterilization results of different sterilization treatments and the effect of different seed sizes on the survival rate of aseptic seedlings. [ Result] Sterilization of H. ammodendron （ C.A. Mey. ） seeds achieved the best result by using 75% alcohol for 15 min and 0.1% mercuric chloride for 8 min. Seeds with diameter φ 〉 2.0 mm were used as explants and achieved relatively high surviv- al rate of aseptic seedlings, which reached above 65%. [ Conclusion] This study established a surface sterilization method for tissue culture of H. ammodendron （ C. A. Mey. ） Bunge seeds.

Study on Sterilization Method of Endophytic Fungi in Tall Fescue(Festuca arundinacea)and Ryegrass(Lolium perenne)Seeds

[Objectives]This study was conducted to obtain the best solution for sterilizing tall fescue(Festuca arundinacea)and ryegrass(Lolium perenne)seeds by heating in a water bath for a short time.[Methods]The tall fescue and ryegrass seeds infected with endophytic fungi were sterilized by heating in a water bath to compare seed germination and initial growth of turfgrass seedlings under different treatment time.[Results]Sterilization in a 60℃water bath for 20 and 30 min both inhibited the germination of tall fescue and ryegrass seeds,while the 20 min treatment did not significantly affect the lengths of stems,leaves and roots of seedlings.The 20 min water bath sterilization treatment had no effects on the plant heights and biomass of the two turfgrass seedlings and the tiller number of ryegrass,but sterilization for 30 min significantly reduced the aboveground and total biomass of seedlings and the tiller number of ryegrass.[Conclusions]Sterilization in a water bath at 60℃ for 20 min achieved rapid sterilization in a short time,without significantly negatively affecting the growth of seedlings.

Nonsurgical method of female sterilization in china

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Preparation and utilization of phosphate biofertilizers using agricultural waste

In this study, Aspergillus niger 1107 was isolated and identified as an efficient phosphate-solubilizing fungus （PSF）. This strain generated 689 mg soluble P L-1 NBRIP medium after 10 d of culture. To produce an affordable biofertilizer using A. niger 1107, the potential of widely available carrier materials for growth and maintenance of this strain were evaluated. The effects of sterilization procedures （autoclaving and gamma-ray irradiation） on the suitability of these carriers to maintain growth of the fungus were also investigated. The carrier materials were peat, corn cobs with 20% （w/w） perlite （CCP）, wheat husks with 20% （w/w） perlite （WHP）, and composted cattle manure with 20% （w/w） perlite （CCMP）. In the first 5-6 mon of storage, the carriers sterilized by gamma-ray irradiation maintained higher inoculum loads than those in carriers sterilized by autoclaving. However, this effect was not detectable after 7 mon of storage. For the P-biofertilizer on WHP, more than 2.0× 10^7 viable spores of A. niger g-1 inoculant survived after 7 mon of storage. When this biofertilizer was applied to Chinese cabbage in a pot experiment, there were 5.6×10^6 spores of A. niger g-1 soil before plant harvesting. In the pot experiment, Chinese cabbage plants grown in soil treated with peat- and WHP-based P-biofertilizers showed significantly greater growth （P〈0.05） than that of plants grown in soil treated with free-cell biofertilizer or the CCMP-based biofertilizer. Also, the peat- and WHP-based P-biofertilizers increased the available P content in soil.

On a reaction-diffusion model for sterile insect release method on a bounded domain

We consider a system of partial differential equations that describes the interaction of the sterile and fertile species undergoing the sterile insect release method （SIRM）. Unlike in the previous work [M. A. Lewis and P. van den Driessche, Waves of extinction from sterile insect release, Math. Biosci. 5 （1992） 221 247] where the habitat is assumed to be the one-dimensional whole space ~, we consider this system in a bounded one- dimensional domain （interval）. Our goal is to derive sufficient conditions for success of the SIRM. We show the existence of the fertile-free steady state and prove its stability. Using the releasing rate as the parameter, and by a saddle-node bifurcation analysis, we obtain conditions for existence of two co-persistence steady states, one stable and the other unstable. Biological implications of our mathematical results are that： （i） when the fertile population is at low level, the SIRM, even with small releasing rate, can successfully eradicate the fertile insects; （ii） when the fertile population is at a higher level, the SIRM can succeed as long as the strength of the sterile releasing is large enough, while the method may also fail if the releasing is not sufficient.