The Function Of Architectural Effects And Resource Competition On The Variation Of Gametes Among Flowers In Hosta Ventricosa

Recently, the study on plant reproduction has become one of the most important in ecology, and the study on flowers, the reproductive organs of plant is the basic of plant reproductive ecology. Now, the study focus on variation of gamete number, fruit set and seeds of different species; and to the reasons of variation, different studies had different answers. This study located in Bi Feng Mountain((N28°51′10″～30°56′40″, E101°56′26″～103°23′28″), Ya'an, Sichuan, China, and Hosta ventricosa (Liliaceae),a perennial herb was selected for study material, defoliation and debud treatments were applied in the field experiment, to explore the architectural effects of variation on gametes and response on different resource treatment, and try to get the reasonable explanation. Over more than one year of field experiment and data analysis, the results were as follows:1. Ovule and pollen number increased with inflorescence size significantly at plant and inflorescence level in Hosta ventricosa (p<0.05),but not pollen of Middle position(r=0.261,p=0.087); there is no significant correlation between p:o ratio and inflorescence size(p>0.05); After defoliation, the significant correlation between pollen number and inflorescence size disappeared at plant and Top position (p=0.095,0.780),and just the pollen number of Bottom increased with inflorescence size significantly(r=0.329,p=0.047); with the disappear of significant correlation between inflorescence size and pollen number of plant and Top position, the p:o ratio decreased significantly with inflorescence size(r=-0.382,-0.401;p=0.023,0.014). There was a more stable and stronger correlation between ovule number and inflorescence size than pollen, and stronger at plant, Bottom and Top position, more stable at Bottom position for pollen.2. There was a position-dependent gamete production within inflorescence in Hosta ventricosa, the plant allocated more resources to Bottom than Middle and Top position, pollen, ovule and p:o ratio decreased significantly from Bottom to Top position; pollen and p:o ratio decreased greatly from Middle to Top than from Bottom to Middle position, ovule was inverse; defoliation significantly increased the pollen and ovule number of plant,but no significant variation in p:o ratio; there was no significant variation of gamete at the same position between control and defoliation, except the pollen of Top position(pollen of Top increased significantly after defoliation, p=0.039); after defoliation, the gamete production decreased slower from Bottom to Top position, but not significantly, defoliation didn't change the resource allocation to different positions within inflorescence.3. Ovule number of Top position increased significantly with inflorescence size at all treatments with different resource treatments(p<0.001);there was a significant increased correlation between pollen of Top and inflorescence size for control-unfruiting, control-fruiting and defoliation-fruiting(p<0.05),but not p:o ratio(p>0.1); and a significant decreased correlation between p:o ratio of Top and inflorescence size for defoliation-unfruiting and debud(p<0.05),but not pollen number(p>0.5).4. After removing the flower buds of Bottom and Middle position, the pollen of Top position decreased significantly, there was no variation in ovule,but to the Bottom of control the ovule decreased significantly; the fruiting of Bottom and Middle flowers didn't change the gamete production of Top position;After defoliation, fruiting of Bottom and Middle flowers significantly decreased the gamete production of Top flower.5. There was resource competition between vegetative growth and reproductive growth, defoliation significantly increased the resource allocation to reproductive gametes;The decreased of gamete production from Bottom to Top within inflorescence was due to Architectural effects; undefoliation, there was no resource competition between developing fruit and flower within inflorescence because of different resource sink, with defoliation, there was resource competition between developing fruit and flower within inflorescence because of the same resource sink. But architectural effects was the main.