Synthesis,algal inhibition activities and QSAR studies of novel gramine compounds containing ester functional groups

2,5,6-Tribromo-l-methylgramine （TBG）, isolated from bryozoan Zoobotryon pellucidum was shown to be very efficient in preventing recruitment of larval settlement. In order to improve the compatibility of TBG and its analogues with other ingredients in antifouling paints, structural modification of TBG was focused mainly on halogen substitution and N-substitution. Two halogen-substitute gramines and their derivatives which contain ester functional groups at N-position of gramines were synthesized. Algal inhibition activities of the synthesized compounds against algae Nitzschia cIosterium were evaluated and the Median Effective Concentration （EC50） range was 1.06-6.74 lag ml^-1. Compounds that had a long chain ester group exhibited extremely high antifouling activity. Quantitive Structure Activity Relationship （QSAR） studies with multiple linear regression analysis were applied to fred correlation between different calculated molecular descriptors and biological activity of the synthesized compounds. The results show that the toxicity （log （I/EC50）） is correlated well with the partition coefficient log P. Thus, these products have potential function as antifouling agents.

The Effects of Peanut Intercropping with Different Gramineous Species and Their Intercropping Model on Iron Nutrition of Peanut

The effects of peanut intercropped with five different gramineous species with different phyto-siderophore release rate on iron nutrition of peanut were studied in field experiment. The rate of phyto-siderophore release of five gramineous species was as following: barley>oats>wheat>>maize>sorghum. The results showed that intercropping of peanut with five gramineous species could improve iron nutrition of peanut respectively. This indicated that root exudates, especially for phytosiderophore of gramineous plants played an important role in improvement of iron nutrition of peanut. Although phytosiderophore release rates of maize and sorghum were lower than those of barley, oats and wheat, the five gramineous species had the same effects on iron improvement of peanut. The less phytosiderophore release of maize was enough to improve iron nutrition of peanut in intercropping system. For every intercropping system, intercropping model I ( the ratio of gramineous plants : peanut : gramineous plants was 2 : 3:2) was much better in improvement of iron nutrition of peanut than that of intercropping model I (the ratio of gramineous plants : peanut: gramineous plants was 2: 6:2). This led to have greater rhizosphere effect of gramineous plants on iron nutrition of peanut in intercropping model I than intercropping model I .

Rumen methane output and fermentation characteristics of gramineous forage and leguminous forage at differing harvest dates determined using an in vitro gas production technique

An in vitro rumen gas production technique was employed to determine the methane production and fermentation characteristics of Leymus chinensis and Medicago ruthenica at differing harvest dates（May 15,May 30,June 30,July 30,August 30 and September 30）,which are sequential phases within a single continuous growth of two 10-year-old pastures.To quantify the rate of degradation and compare in vitro rumen fermentation characteristic,a logistic-exponential model,where initial gas volume was zero（LE_0）,was used to fit gas production and methane output results.Dried,milled forage samples were incubated in vitro for 72 h at 39℃ and gas production was recorded intermittently throughout the incubation and gas samples were collected to measure methane production.Results showed that there were significant interactions between species and harvest for all chemical composition variables（P〈0.001） and condensed tannin content（P〈0.001）.L.chinensis produced more total gas and methane than M.ruthenica（P〈0.001）.Both total gas and methane production decreased lineally（P〈0.001） with advancing harvest date.The degradation rates of L.chinensis and M.ruthenica harvested on September 30 were lower than those on the other harvest dates（P〈0.01）.M.ruthenica fermented fluid had higher concentration of ammonia N（P〈0.05） and molar proportions of isobutyrate（P〈0.01）,valerate（P〈0.001） and isovalerate（P〈0.01） in total volatile fatty acids than L chinensis.Furthermore,concentration of isovalerate decreased cubically with advancing harvest date（P〈0.05）.In conclusion,M.ruthenica produced less methane than L.chinensis and the total gas and methane production decreased with advancing harvest date for both species,which may be due to the changes in contents of chemical compositions and condensed tannin in forages.

Seed germinating characteristics of 54 gramineous species in the alpine meadow on the eastern Qinghai-Tibet plateau

The germination experiment was started on March 3,2004,and seeds were collected from July to October in 2003.We analyzed the percentage of germination,days to first germination,germination period and days to 50%germination.Among the 54 examined species,26 species exceeded 80%germination,11 species exceeded 60%–80%germination,8 exceeded 40%–0%,5 exceeded 20%–40%,and 4 showed less than 20%.A principalcomponent analysis revealed that the species were distributed along two statistically independent axes,the first primarily represented the germination rate and the second represented the time of germination process.Based on scores of germination characteristics,cluster analysis of the 54 gramineous species could be divided into 4 distinct groups:rapid,slow,intermediate germinating(germination percentage>50%),and low germinating(germination percentage<50%).The meaning of different groups to the vegetation regeneration was discussed.