[Effects of exogenous nitrogen addition on litter decomposition and nutrient release in a temperate desert]. / å¤–æºæ°®æ·»åŠ å¯¹æ¸©å¸¦è’æ¼ åœ°è¡¨å‡‹è½ç‰©åˆ†è§£åŠå »åˆ†é‡Šæ”¾çš„å½±å“.

A litterbag decomposition experiment was carried out in southern Gurbantunggut Desert, with four nitrogen treatments: N0(0 g N·m-2·a-1), N5(5 g N·m-2·a-1), N10(10 g N·m-2·a-1) and N20(20 g N·m-2·a-1). The aims were to examine the effects of exogenous nitrogen addition on decomposition rate and nutrient release of Tamarix ramosissima, Salicornia europaea and their mixture. Results showed that decomposition rates were significantly different among litter types. After 345 days, the decomposition rates of T. ramosissima, S. europaea and their mixture under different treatments were 0.64-0.70, 0.84-0.99 and 0.71-0.81 kg·kg-1·a-1, respectively. Both mono- and mixed-litters exhibited nutrient release during decomposition process, with the release rates being 60.6%-67.4%, 56.7%-62.6%, 57.4%-62.3%, 46.8%-63.0% for N, and 51.9%-77.9%, 59.9%-74.7%, 53.0%-79.9%, 52.3%-76.4% for P, respectively for the N0, N5, N10 and N20 treatments. Nitrogen addition did not affect litter decomposition rate. The dynamics of N and P during decomposition of different litter types showed different responses to nitrogen addition. Nitrogen addition inhibited N and P releases of S. europaea litter and P release of the mixed litter, but did not affect the nutrient release of T. ramosissima. The results suggested that nitrogen input would not promote litter decomposition in temperate desert ecosystems, but might retard the nutrient returning to soil system.

[Effects of nitrogen application level on photosynthate distribution of Korla fragrant pear trees]. / æ–½æ°®æ°´å¹³å¯¹åº“å°”å‹’é¦™æ¢¨å ‰åˆäº§ç‰©åˆ†é çš„å½±å“.

Using 13C pulsed labeling technique, we examined the biomass and carbon accumulation of different organs as well as the distribution characteristics of 13C assimilate of 6-year-old Korla fragrant pear trees under three nitrogen application levels, i.e., 150, 300, and 450 kg N·hm-2 (marked as N1, N2, and N3, respectively). Results showed that the biomass, carbon accumulation, 13C fixation and leaf assimilation capacity of the whole pear tree increased while root to shoot ratio decreased with increasing nitrogen application. Both biomass and carbon accumulation amount of reproductive organs (i.e., fruits) were the highest under N2 treatment. The 13C content and distribution rate of each organ changed dynamically along with increasing nitrogen application. At the new shoot growing stage, leaves and roots had stronger competitive abilities for photosynthate, with 13C distribution rates being the highest under N1 treatment. During fruit swelling and mature stages, leaves and fruits were more competitive, with 13C content and distribution rate in leaves being the highest under N3 treatment and those in fruits being the highest under N2 treatment. According to the absorption and distribution characteristics of carbon assimilate across organs under the three nitrogen application levels, the optimal nitrogen application level for achieving high fruit yield in the 6-year-old Korla fragrant pear tree orchard is recommended as 300 kg·hm-2 .

2-Chloro-N-[(4-chloro-phen-yl)(phen-yl)meth-yl]-N-[2-(4-nitro-1H-imidazol-1-yl)eth-yl]ethanamine.

In the title compound, C(20)H(20)Cl(2)N(4)O(2), the nitro-imidazole ring makes dihedral angles of 17.00 (1) and 60.45 (11)° with the phenyl and chloro-phenyl rings, respectively. The three-coordinate N atom connected to two methyl-ene and one methine C atoms shows pyramidal coordination.