[Effects of combined nitrogen and phosphorus addition on fine root traits of young Machilus pauhoi forest]. / æ°®ç£·é æ–½å¯¹åˆ¨èŠ±æ¥ å¹¼æž—ç»†æ ¹æ€§çŠ¶çš„å½±å“.

Both nitrogen (N) and phosphorus (P) are the main limiting elements for plant growth in terrestrial ecosystems. Fine roots play a critical role in plant growth. To reveal the effects of combined N and P addition on fine root traits of Machilus pauhoi, we performed a field N and P addition experiment in the midmonth from April to September in 2016 and 2017 in a 3-year M. pauhoi forest (N and P supply ratios were 8:1, 10:1, 12:1, 15:1). Both fine root morphological traits (specific root length, specific root area, average diameter, root tissue density) and stoichiometric traits (total carbon content, total nitogen content and carbon-nitrogen ratio) were analyzed. The results showed that the effects of combined application of N and P on fine root raits varied with seasons. In June, fertilization significantly increased specific root area, total nitrogen content and specific root length of 0-1 mm fine root, but decreased root tissuse density, carbon-nitrogen ratio and average diameter of 0-1 mm root. The most obvious change of fine root traits in June was found under the treatment with a N and P supply ratio of 12:1. In December, combined N and P addition significantly increased root tissue density, total nitrogen content, carbon-nitrogen ratio as well as fine root biomass with the diameter of 0-1 mm. The results of principal component analysis showed that different N and P supply ratios exerted different effects on the relationships among fine root traits. Fine root traits were distributed at both ends of Axis 1 when treated with 12:1 N:P, while distributed at Axis 1 and Axis 2 under other treaments. There was a significant negative correlation between fine root average diameter variation and the relative plant growh rate. The relationship among fine root traits, and between fine root traits and the relative growth rate of plant biomass were optimally coordinated at the treament with a N:P ratio of 12:1.

[Effects of short-term combined application of ammonium nitrogen and nitrate nitrogen on the growth and leaf traits of Machilus pauhoi seedlings]. / çŸ­æœŸé“µæ€æ°®ä¸Žç¡æ€æ°®é æ–½å¯¹åˆ¨èŠ±æ¥ å¹¼è‹—ç”Ÿé•¿åŠå¶ç‰‡æ€§çŠ¶çš„å½±å“.

Trees are characterized with selective absorption of different forms of nitrogen. Ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3--N) are the main forms of nitrogen for plant absorption. We examined the differences of absorption between NH4+-N and NO3--N for 1-year-old Machilus pauhoi seedlings planted in local hilly red soil in a pot experiment. A controlled experiment with 7 different NH4+-N/NO3--N treatments was conducted, to study the effects of nitrogen forms and different NH4+-N/NO3--N ratios on the growth and leaf traits of M. pauhoi seedlings. The results showed that there were no significant differences in the relative growth rate of ground diameter (GD), plant height (TH), and biomass (RGR) of M. pauhoi seedlings with different NH4+-N/NO3--N ratios for four months, but these parameters were relatively high under the treatment of NH4+-N:NO3--N=5:5. The seedlings of M. pauhoi didn't show obvious preference for NH4+-N and NO3--N in short term. The extremely low NH4+-N/NO3--N ratio application was unsuitable for their growth. Different NH4+-N/NO3--N application had significant effects on leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), leaf relative water content (LRWC), net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), water use efficiency (WUE), and photosynthetic nitrogen use efficiency (PNUE). M. pauhoi seedlings under the treatment of NH4+-N:NO3--N=1:9 had the highest LA, SLA, Pn, WUE and PNUE. However, the seedlings under the treatment of NH4+-N:NO3--N=9:1 had the lowest LDMC, leaf tissue density (LTD), LRWC and Ci. Different NH4+-N/NO3--N combined application did not affect leaf nitrogen content (LN) and leaf phosphorus content (LP), which were highest under the treatment of NH4+-N:NO3--N=5:5. Across different NH4+-N/NO3--N combined treatments, GD, TH, and RGR were significantly negatively correlated with SLA, while both GD and RGR were significantly negatively correlated with PNUE. Our results could provide theoretical basis for precise nutrient management and high-efficiency cultivation techniques during the seedling stage of the M. pauhoi.

[Stoichiometry of carbon, nitrogen and phosphorus and their allometric relationship between leaves and fine roots of three functional tree seedlings.] / 3ç§åŠŸèƒ½åž‹æž—æœ¨å¹¼è‹—å¶ç‰‡ä¸Žç»†æ ¹ç¢³æ°®ç£·åŒ–å­¦è®¡é‡ç‰¹å¾åŠå ¶å¼‚é€Ÿå ³ç³».

We analyzed the contents and stoichiometric ratios of carbon (C), nitrogen (N) and phosphorus (P) in leaves and fine roots of Machilus pauhoi (an evergreen broad-leaved species), Cerasus campanulata (a deciduous broad-leaved species) and Fokienia hodginsii (an evergreen coniferous species) to compare the leaf and root stoichiometry and allometric relationship between different functional groups of trees. There were significant difference in the contents and stoichiometry of C, N and P in the leaves and fine roots among different functional groups. C content, C/N and C/P of the leaves and roots were the highest in M. pauhoi. N content and N/P of the leaves and roots were the highest in C. campanulata, whereas P content of the leaves and roots was the highest in F. hodginsii. The allometric relationship of C, N and P contents as well as their stoichiometric ratios between the leaves and fine roots showed significant difference, which was affected by functional difference. The allometric relationship between C/P and N/P with significantly different allometric indexes in leaves in seedlings of those three tree species, while the isometric relationship between the contents of N and P was found in fine roots. There were significant difference in the C, N and P stoichiometry between the leaves and fine roots. The allometric relationship between leaf C content and root P content in M. pauhoi was detected. C and N contents and C/N, N/P in leaves generally had the allometric or isokinetic relationships with C/N, N/P of fine roots. There were allometric relationships between the leaf C content and the root C, N and P contents in F. hodginsii. It was concluded that nutrient allocation between leaves and fine roots of C. campanulata was more strongly coordinated. The investment strategy of P for leaves and fine roots across those three tree species was similar. The results provided scientific reference for accurate nutrient management at seedling stage and efficient cultivation technique.

[Relationship between the main functional traits of fine root and the rhizosphere soil nutrients of different diameter classes in Zenia insignis plantation.] / ç¿ èšæœ¨äººå·¥æž—ä¸åŒå¾„é˜¶é—´ç»†æ ¹ä¸»è¦åŠŸèƒ½æ€§çŠ¶ä¸Žæ ¹é™ åœŸå£¤å »åˆ†çš„å ³ç³».

Fine roots are sensitive to changes in the soil environment, and play an important role in plant growth and development. To clarify the relationship between fine root traits and rhizosphere soil nutrient characteristics, fine roots of trees belonging to different diameter classes in six-year-old Zenia insignis plantation were sampled. The results showed that root biomass, root length density and root volume density increased with the increases of diameter class. Specific root length and specific root area showed the trend of first rising and then falling and rising again with the increases of diameter class. Root tissue density did not change with diameter class. There were significant diffe-rences in soil pH, water content, total carbon, total phosphorus, ammonium nitrogen, nitrate nitrogen and total available nitrogen contents of rhizosphere soil belonging to different diameter classes. The concentrations of soil total carbon, total nitrogen, nitrate nitrogen and total available nitrogen in the rhizosphere soil of large diameter trees were relatively higher, while the soil water content, total phosphorus and ammonium nitrogen contents of small diameter trees were relatively higher. The concentrations of soil total nitrogen, total carbon, nitrate nitrogen and total available nitrogen were significantly positively correlated with root biomass, root length density and root volume density. The concentrations of soil total phosphorus was significantly positively correlated with root tissue density of fine roots, but negatively correlated with specific root length and specific root area. Soil water content was significantly positively correlated with root biomass and root volume density. Soil pH was significantly positively correlated with the specific root length and specific root area of fine roots, but negatively correlated with root tissue density. Our results provide scientific basis for the selection of excellent germplasm resources of Z. insignis.

Effect of biodegradable polymer drug-eluting stents versus biocompatible polymer everolimus-eluting stents: a meta-analysis.

OBJECTIVE: Biocompatible polymer everolimus-eluting stents (EES) are associated with risk of stent thrombosis (ST); biodegradable polymer drug-eluting stents (BP-DES) were designed to reduce these risks. However, the long-term benefits are not completely clear. METHOD: We undertook a meta-analysis of randomized studies identified in systematic searches of MEDLINE, EMBASE, and the Cochrane Database. Primary outcome was the risk of ST. RESULTS: Twelve studies (11,692 patients) were included. Overall, compared with EES, BP-DES were associated with a broadly equivalent risk of definite and probable ST (OR, 0.91; 95% CI, 0.55 to 1.50; P = 0.71; I2 = 0.0%), early ST (OR, 2.25; 95% CI, 0.78 to 6.47; P = 0.13; I2 = 0.0%), late ST (OR, 3.57; 95% CI, 0.42 to 30.58; P = 0.25; I2 = 0.0%) and very late ST (OR, 0.50; 95% CI, 0.05 to 5.52; P = 0.57). Meanwhile, there was no significant difference in all-cause mortality (OR, 1.07; 95% CI, 0.86 to 1.32; P = 0.54; I2 = 0.0%), myocardial infarction (OR, 1.07; 95% CI, 0.88 to 1.30; P = 0.47; I2 = 0.0%), target vessel revascularization (OR, 1.02; 95% CI, 0.86 to 1.21; P = 0.80; I2 = 12.0%), and major adverse cardiac events (OR, 1.04; 95% CI, 0.93 to 1.16; P = 0.53; I2 = 0.0%). Furthermore, angiographic data showed that in-stent and in-segment late luminal loss were similar between the two groups. CONCLUSIONS: Compared with biocompatible polymer EES, biodegradable polymer stents appear to have equivalent clinical benefits.

[Graft hybridization and the specificity of heredity in fruit trees].

Emphatically discusses the relationship between graft hybridization and the specificity of heredity in fruit trees on the basis of introducing the recent achievements in plant graft hybridization. We propose that genetic materials in rootstock being translocated and integrated into the genome of the germ cells and embryonic cells in scion are the main reasons why the majority of the hybrid seedlings have wild properties and the heredity of fruit trees violate Mendel's laws of heredity. The potential of graft hybridization in fruit breeding are also discussed.