Study On Relationship Among Carbon And Nitrogen Metabolisms And Spike Formation From Tillers In Two Winter Wheat Cultivars With Different Spike Types

Under field experiments and pot experiments,two winter wheat cultivars were planted in growth season during 2006-2008 at Henan Agricultural University research station,which were large spike cultivars"Lankaoaizaoba"(L-8) whose ear formation rate from tillers is low and multi spike cultivars"Yumai 49-198"(Y-49) whose ear formation rate from tillers is high. Three different plant density levels were used in the experiments, the difference of carbon and nitrogen metabolism between main stem and tillers and whose effects on ear formation rate were studied, The main Results were as follows:1. There are some differences in tillers developmental dynamics of two winter wheat cultivars with different spike types. The tillers number per plant of L-8 was higher than Y-49 before setting stage, there is not significant differences between L-8 and Y-49 from setting stage to prophase jointing stage, The tillers number per plant of Y-49 reduce faster relatively from middle jointing stage(18/3). The results suggested that the amount of small tillers from next year spring of Y-49 is small, ineffective tillers decline in short time, but whose finally ears are more than L-8's significantly. The Regulating effect of planting density on the tillers number per plant of two winter wheat cultivars with different spike types is significant; the higher planting density is the lower tillers number per plant is. The number of finally ears per plant of Y-49 in D1 treatment(1500 thousand plants per ha.) is 4.3, in D2 treatment(2625 thousand plants per ha.) is 2.6, in D3 treatment(3750 thousand plants per ha.) is 1.85, The number of finally ears per plant of L-8 in D1,D2andD3 treatment are 2.51,1.8 and 1.2 respectively.2. There are some differences in leaf net photosynthetic rate (Pn) between main stem and tillers of two winter wheat cultivars, as well as the minimal Fluorescence (Fo) and the maximal photochemical efficiency of PhotosystemⅡ(Fv/Fm). The above mentioned differences between main stem and non-earbearing tillers gradually increased from jointing stage, especially for L-8. The main stem of L-8 has much superiority in the maximal photochemical efficiency of PhotosystemⅡ(Fv/Fm), neither is Y-49. There are significant difference in the ratio of tillers'Pn to main stem's Pn, at anaphase of jointing stage the non-earbearing tillers'ratio of tillers'Pn to main stem's Pn in both L-8 and Y-49 are less than 0.7.The non-earbearing tillers'Fo is more than main stem's significantly, neither is Fv/Fm at anaphase of jointing stage(27/3). At Middle of and anaphase of jointing stage, the effects of plant density on Pn, Fo and Fv/Fm is significant, the more plant density is the more the difference between main stem and tillers is.3. Dry matter accumulation of main stem and tillers of two winter wheat cultivars increase gradually with plant growthing, but the rate of dry matter accumulation of main stem is more than that of tillers. The higher the plant density is the low the rate of dry matter accumulation is, but the decrease amplitude of the rate of the main stem is much smaller, especially for L-8.Comparing with the weight of dry matter ratio of tillers to main stem(Ⅰ/ O&Ⅱ/ O), the value of earbearing tillers was increasing, but that of non-earbearing tillers was decreasing from middle of and anaphase of jointing stage. At anaphase of jointing stage(27/3), for L-8, the weight of dry matter ratio of tillers to main stem of earbearing tillers is 0.54, that of non-earbearing tillers is 0.29, for Y-49,the value are 0.66 and 0.46, respectively.4. There are some differences in the soluble sugar content of the tillering node and stem-sheath between L-8 and Y-49.Before jointing stage, the soluble sugar content of the tillering node and stem-sheath in Y-49 is higher than that of L-8.At middle of jointing stage, the soluble sugar content of the tillering node and stem-sheath in L-8 is increasing rapidly and higher than that of Y-49 finally, but the differences of soluble sugar content between non-earbearing tillers and main stem is significant, the non-earbearing tillers are decline. At prophase of and middle of jointing stage(12/3-23/3), the soluble sugar content of stem-sheath of main stem in two winter wheat cultivars increase rapidly or decrease slowly, and the differences between non-earbearing tillers and main stem in Y-49 are small. The results suggested that the effect of the soluble sugar content on ear formation rate is significant At prophase of and middle of jointing stage(12/3-23/3), and the higher the soluble sugar content is the higher the ear formation rate is and vice versa. The effect of plant density on soluble sugar content is significant, the higher the plant density is the lower the soluble sugar content is. In most time, the soluble sugar content of the tillering node in Y-49 is higher than that of L-8. 5. At jointing stage, the activity of SPS in the main stem of L-8 is higher than that of tillers, as well as that of Y-49. at middle of and anaphase of jointing stage, The rising rate of the activity of SPS in the main stem of L-8 is higher than that of tillers significantly, the differences of the rising rate of the activity of SPS between tillers and main stem in Y-49 are small. The effect of plant density on the activity of SPS is significant, the higher the plant density is the greater differences of the activity of SPS between tillers and main stem is. For D3 treatment, the activity of SPS in non-earbearing tillers is lower than that of main stem at jointing stage.6. There are some differences in the distribution of 14C–assimilation between main stem and tillers. The output of 14C–assimilation of main stem in L-8 is lower than that of Y-49. The occupation of first tiller in L-8 is 2% more than that of Y-49, but the output to second tiller is less than that of Y-49. The output of 14C–assimilation from second tiller to first tiller and main stem in L-8 is higher than that of Y-49. At jointing stage, the output of 14C–assimilation from main stem to tillers increases significantly in Y-49.7. From wintering period to jointing stage, the change trend of total nitrogen content of tillering node likes"M". Before jointing stage, the total nitrogen content of tillering node in L-8 is lower than that of Y-49, but after jointing stage, the total nitrogen content of tillering node in L-8 is higher than that of Y-49. At middle of and anaphase of jointing stage (after 18/3), the total nitrogen content of tillering node in L-8 is higher, and decrease slowly. The change trend of total nitrogen content of stem-sheath likes that of tillering node. There are significant differences in total nitrogen content of stem-sheath between main stem and tillers; the total nitrogen content of stem-sheath in main stem is much lower than that of non-earbearing tillers. The effect of plant density on the total nitrogen content is significant, the higher the plant density is the greater differences of the total nitrogen content between tillers and main stem is. 8. From setting stage to jointing stage, the activity of GS in two winter wheat cultivars increases firstly and decreases at the end of jointing stage. There are significant differences in activity of GS between main stem and tillers in L-8, at jointing stage, the activity of GS of main stem in L-8 increases, and the results show that the main stem of L-8 has much superiority in activity of GS. The effect of plant density on the activity of GS is significant, the higher the plant density is the lower the activity of GS in tillers is, the higher differences in the activity of GS between tillers and main stem is.The main stems of two winter wheat cultivars have much superiority in occupation of 15N–assimilation, especially for L-8. At jointing stage, the occupation of 15N–assimilation of second tiller in L-8 is lower than that of Y-49; this is one of reasons of why ear formation rate is lower than that of Y-49.9. The results of Correlation analysis between ear formation rate and the soluble sugar content of the tillering node or the ratio of carbon to nitrogen show that, the ear formation rate is positively and significantly correlated with the soluble sugar content of the tillering node or the ratio of carbon to nitrogen. With the nitrogen nutrition stabilizing, improving photosynthetic performance and increasing the soluble sugar content and the ratio of carbon to nitrogen in the tillering node can increase ear formation rate.