Differentiation of Seed Germination and Early Seedling Growth in Ten Provenances of Eucalyptus Microtheca

An investigation of seed germination and early seedling growth of Eucalyptus microtheca was based onseed collection from 10 widely,separated provenanes in Australia. Genetic variation of seed germination and carly seedling growth was observed among a series of provcnances whose natural habitats range from different climatic condition Inthe ten provenances, both the model of seed relative germination percentage and the model of seed total germination percentage fitted Logistic regression [y=a/(1+exp(-cx+b))]. In comparison with provenanccs from four high temperature (meanannual maximum temperature >30.0 ℃: mean annual minimum temperature > 17.0 ℃) areas, six low temperature (meanannual maximum temperature <30℃, mean annual minimum temperature <17.0 ℃) areas showed the thst genninationrate and the high total germination percentage, For each provenance we have 45 seedlings equally divided into three watering levels (100%, 50%. and 25% of field capacity), and studies on relationship between early seedling growth and climaticfactors of the natural habitat of provenance. In control treatment. height growth of the seedling has beeb associated with intrinsically the driest quarter precipitation in the seed collection areas of provenance. In all the treatments, length growth ofthe biggest Ieaf of the seedling was related to mean annual maximum temperature and mean annual minimum temperaturein origin of provenance. In contrast, basal diameter growth of the seedling was related to mean annual minimum temperature of the seed collection areas in water stress treatment. From an ecological viewpint, the fast germination rate and thehigh total germination perecntage of the seed and rapid early grouth of the seedling appear to bc favourable adaptations tothe climatic conditions prevailing in the natural habitat of provenance.

Allelopathic Effects of Cedrus deodara Needle Extracts on Seed Germination and Early Growth of Three Turfgrasses

[Objectives]This study was conducted to provide reference for plant landscaping,optimization of planting structure and rational allocation of species in Cedrus deodara gardens.[Methods]With three common garden plants in northern China,Trifolium repens L.,Poa pratensis L.and Trifolium pratense L.,as receptors,the effects of four concentrations(0.025,0.05,0.075 and 0.10 g/ml)of C.deodara needle extract on seed germination and early seedling growth of the three turfgrasses were studied by the Petri dish filter paper method,using a clear water treatment(0 g/ml)as control check(CK).Data were subjected to analysis of variance(ANOVA)and multiple comparisons(Duncan)using SPSS16.0.[Results]Different concentrations of C.deodara needle extract had significant inhibitory effects on seed germination,radicle and seedling height growth of T.repens,T.pratense and P.pratensis(P<0.05),and the inhibitory effects increased with the increase of concentration.When the concentration reached 0.075 g/ml,seed germination and seedling growth of T.repens stopped,and radicle and seedling growth of T.pratense and P.pratensis also stopped.When the concentration was equal to 0.10 g/ml,germination of T.pratense and P.pratensis seeds was inhibited,and the absolute values of allelopathic index was the largest,that is,the inhibitory effects were the largest.And with the increase of concentration,the absolute value of synthetical allelopathic index also increased.The extract of C.deodara needles contained main allelochemicals leading to the scarcity of understory vegetation.[Conclusions]This study provides a theoretical basis for reasonable garden plant configuration during C.deodara greening and garden landscaping.

Pre-sowing treatments for improved germination and growth of two rare native species of Bangladesh

Pre-sowing treatments are expected to increase seed germination.This evaluates response to pre-sowing treatments and the growth performance of two native and rare tree species,Garuga pinnata Roxb.and Vitex glabrata R.Br.The hard seed coats were treated by rubbing with sand paper,nail clipping,and immersion in water and acid（H_2SO_4）.Results indicate that G.pinnata showed a 90% germination rate and 30% germination energy when seed coats were nicked with a nail clipper.Rubbing with sand paper was the best pre-sowing treatment for V.glabrata,resulting a 80% germination rate and 30% germination energy.G.pinnata and V.glabrata seedlings from seeds soaked 24h in water resulted in maximum heights and collar diameters.These were significantly higher（at p〈0.05） than those of other treatments.The results indicate that scarification or nicking of seeds may have some negative impacts on seedling growth.Therefore,it is difficult to recommend a pre-sowing treatment of seeds for achieving both maximum germination and good early seedling growth.