This experiment is designed with four planting row widths of 1.0,1.1,1.2 and 1.3 m,with mechanical harvesting,to study the effects of mechanical harvesting on the ratoon cane and soil bulk density.The result shows that mechanical harvesting has different effects on different planting row width,ratoon cane buds of underground and sugarcane stubble cane cracking.The total bud numbers of 1.2 m and 1.3 m treatments are significantly higher than that of 1.0 m and 1.1 m treatments,but the differences between 1.0 m and 1.1 m treatment and 1.2 m and 1.3 m treatment are not significant.The rate of vitality bud of upper bud is significantly lower than that of the under part buds,but the bud numbers of under part of 1.2 m and 1.3 m treatments are significantly higher than that of 1.0 m and 1.1 m treatments.Root vigor of sugarcane ratoon increases with the increase of planting row width.Mechanical harvesting has different effects on the soil bulk density of different planting distance from stubble,planting row width and different soil layers.In the place of 5 cm from stubble,soil bulk density of soil layer above 20 cm increases with the increase of planting row width,while in the place of 10-20cm from stubble,the difference of soil bulk density between the planting row width treatments is not significant.

The present experiment was conducted using sweet potato with no-tillage and rice straw coverage in lateritic soil of paddy field to study the effects of different tillage conservation modes on carbon,nitrogen and nitrogen mineralizing bacteria in soil and their correlation.The results indicated that conserving tillage could increase the content of total organic carbon,active organic carbon,total nitrogen and alkali-hydrolyzable nitrogen in the soil layer of 0-10cm,while decreased the C / N ratio in soil.The quantity of ammonifying bacteria in different tillage conservation treatments increased twice compared to traditional tillage in both,0-10 as well as in 10-20cm soil layer.Further,the quantity of nitrifying bacteria in different tillage conservation treatment significantly differed from that of traditional tillage in 0-10cm soil layer,while no significant difference was observed in 10-20 cm soil layer.These results demonstrated that conserving tillage could increase the contents of organic carbon and nitrogen,and decrease the C / N ration in soil which is beneficial for the growth of nitrogen mineralizing bacteria and provide more available nitrogen for the crops.

The adaptability experiment of introduced super hybrid rice variety Yongyou 6 was conducted in Nanning in 2007-2008.The results of plot and field experiments showed that Yongyou 6 was characterized by early maturing,large panicle,high yield,good grain quality,resistance to lodging and diseases,etc.The whole growth duration of Yongyou 6 was 115-120 days,and was five and ten days earlier than that of the controls Boyou 253 and Zhongzheyou 1,respectively.The average yield was 8731.5kg / hm2 and increased by 10.2% compared to the control Boyou 253.Moreover,the location of increasing yield was 85% in the experiment,and Yongou 6 had the potential of super high yield and suitable for planting as late rice in Nanning.The key cultivation measures included cultivation by cast-transplanting of young seedlings,promoting root for vigorous tillers,high fertilizer with water control,and so on.

In the experiment,winter-planting potato variety Zaodabai was used to compare the effects of five different cultivation models on the chlorophyll content in leaves,root activity,nitrate reductase activity in leaves of potato,etc.Five different cultivation models included conventional cultivation model,micro-tillage with rice straw covering,no-tillage with rice straw covering,no-tillage with rice straw and common plastic film covering,no-tillage with rice straw and black plastic film covering.The results showed that the content of chlorophyll,the activities of nitrate reductase,sucrose invertase and amylase in leaves and root activity for micro-tillage with rice straw covering were relatively higher at different stages,that of conventional cultivation model was lower,and that of other treatments had no obvious difference.Moreover,conventional cultivation model made the plants be prone to premature senescence.Therefore, micro-tillage with rice straw covering model was suggested for winter-planting potato in clay loam soil,and conventional cultivation model for sandy loam soil,which were beneficial to regulate the physiological metabolism process of potato plant,and improved the yield and quality of potato.

This paper presents a novel 2.45GHz quasi-elliptic low-temperature co-fired ceramic(LTCC) low-pass filter with spiral transmission lines,and proposes the analytical equation to determine an positions of the transmission zeros at the rejection area.By considering the parasitic coupling effect of spiral transmission lines in the actual LTCC structure,the equivalent circuit of the filter is modified,which enables the simulated scattering parameter curves of the equivalent circuit to accord well with the measured ones.It is indicated by measurement that the proposed low-pass filter is of good performance and meets the requirements of application well.

A LTCC second order low-band pass filter with transmission line has been proposed in this paper. With the periodic property of the transmission line, the filter provides two transmission zeros at rejection area to enhance performance of the low-band pass filter. The simulation results have demonstrated the good performance of this low-pass filter

目前在生产上应用的两系杂交水稻具有秧苗素质好,抗逆性强,前期长势明显,株型良好,穗大粒多,产量高,米质好等优点,但也存在成穗率、结实率较低,成熟中后期易早衰的问题.