Reproductive Biology Of Casuarina

The crossbreeding of Casuarinaceae is a very important method of Casuarinaceae genetic improvement. The Use of hybrids advantage is particularly prominent in modern breeding, sexual hybrid seed production can greatly improve the production of plantations,the adaptability and resistance of bad environment. This experiment mainly studied the reproductive and biological of Casuarinaceae, the structure of male and female flowers of Casuarinaceae,pollen viability,the storage time and condition of pollen,he morphology of pollen,different stages of embryo development after pollination and fertilization, and conclusions as follow: 1.The structure of male and female flowers of CasuarinaceaeThe flower of Casuarinaceae is unisexual, it is monoecious or dioecious; catkin. Male inflorescenceis like panicle, it is 1-5cm long, almost no peduncle; 1 stamen and 4 bracts, anther with 2 atrials and 4 ventriculars; female inflorescence is like a ball, and it is on the short lateral branch,shorter wider than male inflorescenceis; female flower has 1 bract and 2 little axillary bracts, no perianth; pistil is formed by 2 carpels. superior ovary,2 rooms initially, then back part degraded into single room, the style is short, and 2 red lineshape stigma. 2. The determination of pollen viabilityThe test results shows that,ifferent concentration of sucrose and boric acid has obvious influence to the germination of pollen. screening the best concentration of sucrose and boric acid for the pollen germination.15% of concentration of sucrose is the best concentration for the germination of Casuarinaceae pollen; adding boric acid to the medium with 15% of concentration of sucrose can improve the pollen germination,250 mgkg-1 of boric acid is the best concentration for the germination Casuarinaceae pollen; the research also proved that the solid medium with agar is better for the germination of Casuarinaceae pollen.The germination of Casuarinaceae pollen is low, the activity is low too, the highest germination is only 13.16% even under the culture condition with the best combination. 3.The storage time and condition of pollenThe research shows that, the germination rate of Casuarinaceae pollen is decreased with the prolongation of the storage time under many kinds of storage time but the difference of descending speed is great under different storage temperature under the condition of room temperature, the germination rate of pollen is only 0.79% after 3days storage, and the pollen has no activity after 7 days storage; under the condition of 4℃in fridge, the germination rate of pollen is only 11.20% after 3days storage,only 8.47%, and it decreased to4.79% after 15 days storage,2.33% after 30 days; but under the condition of-20℃in fridge, the germination rate of pollen is only 13.16% after 3days storage,10.32% afer 7 days storage,9.86% after 15 days storage, and 8.32% after 30 days storage still. It showed that the storage time of Casuarinaceae pollen is very short under the condition of room temperature, most pollen lost its activity after 3 days.The experiment also proved that low temperature can keep the activity of Casuarinaceae pollen effectively, the germination rate of pollen after 30 days storage is 2.0% lower than the one after 7 days.In the experiment of pollen storage,studying the change under different storage condition can provide scientific basis for long time storage and transform of the pollen.4. The observation of the morphological characters of Casuarinaceae pollenThe equatorial view of Casuarinaceae is coccoid form or near spherical,and it has 3 apertures, they distribut on the face of the pollen.We can see from all the pictures, the tree kinds of Casuarinaceae, C. equisetifolia, C. cunninghamiana Miq.and C. glauca Sieber ex Sprengel, the face ornamentation of the pollen all have spikes,but the density of different kinds of spikes is uneven, the rough extent and folds and the size of the pollen is different either.C. equisetifolia: The pollen of C.equisetifolia is near spherical, the ameter is between 28.8-39.2μm, it has roughface and folds, the distributionof of spikes is densely. The pollen of C. cunninghamiana Miq is coccoid form, the ameter is between28.6-38.6μm, it has rough face and folds, the distributionof of spikes is different and it has difference between different clones; The pollen of C. glauca Sieber ex Sprengel is also coccoid form, the ameter is between 27.7-35.6μmm, it has rough face and folds, the smooth degree is different and it has difference between different clones, some has folds while some has no folds, the distributionof of spikes is densely.5.Different stages of embryo development of CasuarinaceaeThe experiment did a simple understand of embryo development, and initial study and research of morphological embryo in different period,but because the sampling time problem, we did not master the hole period of Casuarinaceae embryo development systematicly, and just study the structure of Casuarinaceae ovule simply, so we need to study the hole life cycle of the embryo further more. 6. Seeds of Casuarina ability to resist saltThe experiment has studied the seed germination and the growth conditionof seedling of C.montana Miq,C. cunninghamiana Miq.and C. glauca Sieber ex Sprengel under the condition of different concentration of NaCl. And the result showed that the germination rate,vigor index,germination energy,the seedling heightand the root length of the 3 kinds of trees is in a decreased trend. Under the salt stress, the germination rate,germination index,vigor index of the Casuarinaceae seed is decreased with the increase of the concentration of salt, the early growth of seedlings after germination is inhibited; the inhibition of seed germination and seedling growth is great with the increase of the concentration of NaCl; when the concentration of NaCl is 0.3%, the decrease amplitude of germination rate,germination index,vigor index,germination energy,the seedling height,the root length and fresh weight were larger than the normal,they were inhibited greatly, but the germination rate between different kinds of Casuarinaceae seed is significant different.