[Effects of organic fertilizer application on flag leaf C/N ratio, photosynthetic characteristics and yield of spring wheat with full plastic film mulching]. / å ¨è†œè¦†åœŸä¸‹æ–½æœ‰æœºè‚¥å¯¹æ˜¥å°éº¦æ——å¶ç¢³æ°®æ¯”ã€å ‰åˆç‰¹æ€§å’Œäº§é‡çš„å½±å“.

A field experiment was conducted in the rain-fed semi-arid region of central Gansu in 2016 and 2017, with the treatments 1) hill-drop flat planting with full plastic film mulching (PMS), 2) hill-drop flat planting with full plastic film mulching plus organic fertilizers (PMO), and 3) hill-drop flat planting without soil mulching (CK). We investigated the relations among soil moisture, photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (Tr), C/N ratio, and total nitrogen of flag leaf from the heading stage to the seed-filling stage in different treatments to probe into their effects on the yield and yield components of spring wheat variety 'Longchun 27'. The results showed that organic fertilizer application could increase soil moisture at the middle and late growth stages of spring wheat. PMO increased soil water storage in 0-300 cm depth from the heading stage to the seed filling stage by 4.6% and 8.5%, decreased population canopy temperature by 0.1-1.3 ℃ and 1.4-4.9 ℃, increased net photosynthetic rate of flag leaf by 9.3% and 29.7%, stomatal conductance by 30.9% and 103.8%, transpiration rate by 5.1% and 55.0%, total nitrogen content by 6.6% and 18.9%, and decreased C/N ratio by 6.4% and 22.8%, respectively. Compared with PMS and CK, PMO significantly improved grain number per spike and 1000-grain weight, and increased grain yield by 9.1% and 53.7%, respectively. From the heading stage to filling stage, the Pn and gs of flag leaf had negative correlation with C/N, while C/N was negatively correlated with grain yield. Consequently, PMO could improve soil water storage and promote photosynthesis of flag leaf, reduce the intensity of physiological drought stress and the limitations of nitrogen absorption and assimilation in flag leaf from the heading stage to the seed-filling stage, and increase grain number and grain weight and consequently the yield of spring wheat in semi-arid region.

[Effects of micro-ridge-furrow with plastic mulching and bunching seeding on soil hydrothermal environment and its response to photosynthesis and grain yield of spring wheat]. / å ¨è†œå¾®åž„æ²Ÿç©´æ’­å¯¹æ˜¥å°éº¦åœŸå£¤æ°´çƒ­çŽ¯å¢ƒçš„å½±å“åŠå ¶å ‰åˆå’Œäº§é‡æ•ˆåº”.

The relieving of drought and cold restriction on spring wheat development is one of the key factors increasing wheat yield in arid areas of central Gansu Province. A field experiment with spring wheat (Longchun No. 35) was carried out in central Gansu Province from 2016 to 2018. There were three treatments: 1) micro-ridge-furrow with whole field plastic mulching and bunching seeding (PRF), 2) whole field soil plastic mulching and bunching seeding (PMS), 3) bunching seeding without mulching (CK). We measured soil temperature in 0-25 cm profile, soil water content in 0-300 cm profile, leaf SPAD, photosynthetic rate, transpiration rate, aboveground biomass in different growth stages, and grain yield to understand the effect of PRF on soil hydrothermal environment, spring wheat yield and water use efficiency (WUE) from the aspect of soil hydrothermal, canopy development and grain yield. The results showed that mean soil temperature in 0-25 cm profile of PRF and PMS increased by 2.8 ℃ and 2.5 ℃ at the seedling stage, decreased by 1.4 ℃ and 0.9 ℃ from filling to maturity stage, respectively. Soil water storage in 0-300 cm profile of PRF and PMS increased by 59.7 mm and 41.8 mm from sowing to seedling stage. Water consumption of PRF and PMS increased by 46.1 mm and 39.8 mm from seedling to filling stage. PRF increased average soil temperature in 0-25 cm profile by 0.3 ℃ at seedling stage, but decreased by 0.5 ℃ from filling to maturity stage, and increased soil water storage in 0-300 cm profile by 18.0 mm from sowing to seedling stage. PMF increased water consumption by 13.0 mm from booting to maturing stage, as compared with PMS. Based on the optimizated soil hydrothermal conditions, leaf SPAD value, aboveground biomass, net photosynthetic rate, and transpiration rate of PRF increased, as compared with PMS and CK. The PRF increased grain yield by 9.1% and 36.5%, WUE by 5.9% and 30.8% compared to PMS and CK, respectively. Consequently, PRF increased soil temperature at wheat seedling stage, reduced it from filling to maturing stage, improved wheat water consumption from sowing to filling stage, increased leaf SPAD value and aboveground biomass, promoted photosynthetic function in leaf from seedling to filling stage, and consequently led to increased yield and water utilization. Such effects were more significant in dry year (2016 and 2017).

[Studies on the crystallization characteristics of the hard segments in ethylene terephthalate-epsilon-caprolactone copolyesters].

The crystallization characteristics of the ethylene terephthalate (ET) hard segments in ethylene terephthalate-epsilon-caprolactone (TCL) copolyesters were studied by wide-angle X-ray diffraction (WAXD) and Fourier transform infrared spectroscopy (FTIR). It was found that in TCL copolyesters with high hard segment content, the ET hard segment can crystallize to form the crystals having the similar lattice structure as that of pure poly (ethylene terephthalate) (PET). The lamellar thickness and the crystallinity of the ET crystals depend on the ET segment sequence length. As the segment sequence length decreases, the lamellar thickness and the crystallinity decrease.