Design of Metering Device Key Parts of Pneumatic Grass Seeder

Based on the mechanical and physical properties study of forage grass seeds, multi-line with one-device type metering device was designed. It was composed of adjustable screw, stirrer, metering device housing and central metering sheave and so on. The sowing rate can be set by turning the screw to change the working length of the central metering sheave relative to the metering device housing. The stirrer inside of the sheave housing is used to prevent seeds overhead. And metering of different sizes of seed is adjusted by changing the position of internal components of the slot wheel mechanism. Innovative design on the structure of the central metering sheave was finished. According to the structure parameters and physical characteristic parameters, different seed sowing rate of per hectares was calculated. And then the working length scale of the central metering groove wheel was made. And there is a one-to-one correspondence between scale values and sowing quantity per hectare of different kinds of seed.

Effect of CaCl2, Citric Acid and Storage Period on Physico-Chemical Characteristics of Cherry Candy

Cherry cultivar Misri （Bigarreau Noir Grossa） was used for making candy. Pitting of fruit was done manually and KMS （0.2%） was added for bleaching. The fruit was pretreated using 4 levels of CaCl2 （Co = 0%, C1 = 1%, C2 = 1.5%, C3 = 2%） and stored in jars for 4 weeks. Thereafter, application of colour was done using Erythrosine （0.05%） followed by dipping pitted fruits in sugar syrup for 24 hours. The samples were treated with 4 levels of citric acid （To = 0%, Tl = 1%, T2 = 1.5%, T3 = 2%） and then concentrated subsequently till desired TSS of 70~ Brix was attained. The samples were dried in cabinet drier at 80 ±20 ℃till constant moisture was attained. The product was packed in polyethene pouches and stored under ambient storage conditions. Results revealed that there was gradual increase in reducing sugars （%）, total sugars （%） during storage while as moisture content （%） decreased. The product developed was found economically profitable and viable for commercial production.

A Study on Photosynthetic Physiological Characteristics of Six Rare and Endangered Species

The parameters of gas exchange and chlorophyl fluorescence in leaves of six rare and endangered species Neolitsea sericea, Cinnamomum japonicum var. cheni , Sinojackia microcarpa, Discocleidion glabrum var. trichocarpum, Parrotia sub-aequalis, Cercidiphyl um japonicum were measured in fields. The results showed that there were significant differences in photosynthetic capacity, intrinsic water use effi-ciency （WUEi ）, the efficiency of primary conversion of light energy of PSⅡ and its potential activity, the quantum yield of PSⅡ electron transport, and the potential ca-pacity of heat dissipation among the six species. However, there was no significant difference in WUE. The highest values of net photosynthetic rate （Pn）, transpiration rate （Tr） and stomatal conductance （gs） occurred in D. glabrum var. trichocarpum and the lowest in S. microcarpa. On the contrary, D. glabrum var. trichocarpum had the lowest WUE, intrinsic water use efficiency （WUEi ） and S. microcarpa had the highest. The results indicated that D. glabrum var. trichocarpum had higher photo-synthetic capacity and poorer WUE, while S. microcarpa had lower photosynthetic capacity and greater WUE. Furthermore, the mean values of maximal fluorescence （Fm）, potential efficiency of primary conversion of light energy of PSⅡ （Fv/Fm）,ΦPSⅡ, actual efficiency of primary conversion of light energy of PSⅡ （F′v/F′m） and non-photochemical quenching coefficient （NPQ） were the highest in S. micro-carpa, indicating that its PSⅡ had higher capacity of heat dissipation and could prevent photosynthetic apparatus from damage by excessive light energy. Correlation analysis showed that there were significant correlations among photosynthetic physi-ological parameters. However, the initial fluorescence （Fo） was not significantly cor-related with any other parameters. This study also revealed the extremely significant positive correlations between Pn and Tr, gs, apparent quantum yield （AQY）, be-tween Tr and gs, between light saturation point （LSP） and AQY, between Fv/Fm and Fm, between ΦPSⅡ and photochemical quenching coefficient （qp）, between Tr, gs and LSP, AQY. However, WUEi was significantly negatively correlated with Tr, gs, Pn, LSP and AQY.

The spatiotemporal characteristics of spring phenophase changes of Fraxinus chinensis in China from 1952 to 2007

We selected widely distributed and well observed plant species Fraxinus chinensis to study the formation mechanism of geographical distribution of the plant phenophase changes and revealed their spatiotemporal dynamics in China. Based on the first leaf date （FLD） data at 12 sites derived from Chinese Phenological Observation Network （CPON） and related meteoro- logical data, we developed and validated the process-based model of FLD for Fraxinus chinensis. After reconstructing data series of FLD for Fraxinus chinensis over the study area from 1952 to 2007, we analyzed different spatiotemporal patterns of phenophase changes of this species. The results suggested that the process-based model was able to simulate the FLD accu- rately for Fraxinus chinensis on large spatial and temporal scales, because of the consideration of different budding rate re- sponded to the air temperatures during the dormancy and the quiescence in accordance with the physiological mechanism of plants. The geographical distribution of the spring phenology in temperate regions was determined by the spatial pattern of daily average air temperature. The changes of FLD for Fraxinus chinensis revealed significant phenological advances in most areas. However, it showed delayed trends in a few sites. The overall average change trend was -1 .l days/decade. This result was consistent with the advanced trend in other regions of the North Hemisphere. The changes of FLD showed a noticeable regional variation with clearer advance in the north than in the south. The FLD in northern China showed an average ad- vance as high as -2.0 days/decade （P〈0.01）. And the advance in northeastern and northwestern China was respectively -1.5 and -1.4 days/decade （P〈0.01）. Furthermore, eastern and central regions showed a minor trend, which was -1.0 days/decade （P〈0.05）. The smallest and non-significant advance appeared in southwestern and southern China.