Improving the yield of maize grain per unit area is needed to meet the growing demand for it in China, where the availability of fertile land is very limited.Modified fertilization management and planting density are ...Improving the yield of maize grain per unit area is needed to meet the growing demand for it in China, where the availability of fertile land is very limited.Modified fertilization management and planting density are efficient methods for increasing crop yield.Field experiments were designed to investigate the influence of modified fertilization management and planting density on grain yield and nitrogen use efficiency of the popular maize variety Zhengdan 958, in four treatments including local farmer＇s practice（FP）, high-yielding and high efficiency cultivation（HH）, super high-yielding cultivation（SH）, and the control（CK）.Trials were conducted in three locations of the Huang-Huai-Hai Plain in northern China.Compared with FP, SH was clearly able to promote N absorption and dry matter accumulation in post-anthesis, and achieve high yield and N use efficiency by increasing planting density and postponing the supplementary application of fertilizers.However, with an increase in planting density, the demand of N increased along with grain yield.Due to the input of too much N fertilizer, the efficiency of N use in SH was low.Applying less total N, ameliorating cultivation and cropping management practices should be considered as priority strategies to augment production potential and finally achieve synchronization between high yield and high N efficiency in fertile soils.However, in situations where soil fertility is low, achieving high yield and high N use efficiency in maize will likely depend on increased planting density and appropriate application of supplementary fertilizers postpone to the grain-filling stage.展开更多
Background The successful end-point of in vitro fertilization （IVF） treatment is for a woman to give live birth. This outcome is based on various factors including adequate number of retrieved eggs. Failure to recru...Background The successful end-point of in vitro fertilization （IVF） treatment is for a woman to give live birth. This outcome is based on various factors including adequate number of retrieved eggs. Failure to recruit adequate follicles, from which the eggs are retrieved, is called a ＂poor response＂. How to improve the clinical pregnancy rates of poor responders was one of the tough problems for IVF. Methods The study involved 51 patients who responded poorly to high dose gonadotropin treatment in their previous cycles at our reproductive center, between April 2010 and February 2012. The previous cycle （group A） received routine long protocol; the subsequent cycle （group B） received modified super-long down-regulation protocol. The primary outcome of the study was the number of oocytes fertilized. The increase in the pregnancy rate was the secondary outcome. Differences between the groups were assessed by using Student＇s t test and Z2 test where appropriate. Results The patients＇ average age was （36.64±3.85） years. The mean duration of ovarian stimulation cycles of the group A patients was longer than those of the group B patients. The total dose of follicle-stimulating hormone （FSH） was significantly lower in the subsequent cycle. The peak value of serum estradiol on human chorionic gonadotrophin （hCG） day was lower in group A as compared with group B. The number of metaphase II oocytes recovered was significantly higher in group B. The cleavage rate in group A was significantly lower than in group B, 49 patients in group B reached embryo transfer stage, while 46 patients in group A reached this stage. Patients in group B received significantly more embryos per transfer as compared with group A. More pregnancies and more clinical pregnancies with fetal heart activity were achieved in group B. Conclusions This comparative trial shows that poor responder women undergoing repeated assisted reproduction treatment using modified super-long down-regulation protocol achieve more oocytes, leading to higher fertilization rate, compared to women receiving routine long protocol. Our study also showed that clinical pregnancy rate was significantly improved.展开更多
基金supported by grants from the National Natural Science Foundation of China(31371576,31071358,31301274)the European Union’s Seventh Framework Programme(NUE-CROPS 222645)+1 种基金the National Key Technology Support Program of China(2011BAD16B14,2012BAD04B05-2)the Special Fund for Agro-Scientific Research in the Public Interest of China(HY12031100,HY1203096)
文摘Improving the yield of maize grain per unit area is needed to meet the growing demand for it in China, where the availability of fertile land is very limited.Modified fertilization management and planting density are efficient methods for increasing crop yield.Field experiments were designed to investigate the influence of modified fertilization management and planting density on grain yield and nitrogen use efficiency of the popular maize variety Zhengdan 958, in four treatments including local farmer＇s practice（FP）, high-yielding and high efficiency cultivation（HH）, super high-yielding cultivation（SH）, and the control（CK）.Trials were conducted in three locations of the Huang-Huai-Hai Plain in northern China.Compared with FP, SH was clearly able to promote N absorption and dry matter accumulation in post-anthesis, and achieve high yield and N use efficiency by increasing planting density and postponing the supplementary application of fertilizers.However, with an increase in planting density, the demand of N increased along with grain yield.Due to the input of too much N fertilizer, the efficiency of N use in SH was low.Applying less total N, ameliorating cultivation and cropping management practices should be considered as priority strategies to augment production potential and finally achieve synchronization between high yield and high N efficiency in fertile soils.However, in situations where soil fertility is low, achieving high yield and high N use efficiency in maize will likely depend on increased planting density and appropriate application of supplementary fertilizers postpone to the grain-filling stage.
文摘Background The successful end-point of in vitro fertilization （IVF） treatment is for a woman to give live birth. This outcome is based on various factors including adequate number of retrieved eggs. Failure to recruit adequate follicles, from which the eggs are retrieved, is called a ＂poor response＂. How to improve the clinical pregnancy rates of poor responders was one of the tough problems for IVF. Methods The study involved 51 patients who responded poorly to high dose gonadotropin treatment in their previous cycles at our reproductive center, between April 2010 and February 2012. The previous cycle （group A） received routine long protocol; the subsequent cycle （group B） received modified super-long down-regulation protocol. The primary outcome of the study was the number of oocytes fertilized. The increase in the pregnancy rate was the secondary outcome. Differences between the groups were assessed by using Student＇s t test and Z2 test where appropriate. Results The patients＇ average age was （36.64±3.85） years. The mean duration of ovarian stimulation cycles of the group A patients was longer than those of the group B patients. The total dose of follicle-stimulating hormone （FSH） was significantly lower in the subsequent cycle. The peak value of serum estradiol on human chorionic gonadotrophin （hCG） day was lower in group A as compared with group B. The number of metaphase II oocytes recovered was significantly higher in group B. The cleavage rate in group A was significantly lower than in group B, 49 patients in group B reached embryo transfer stage, while 46 patients in group A reached this stage. Patients in group B received significantly more embryos per transfer as compared with group A. More pregnancies and more clinical pregnancies with fetal heart activity were achieved in group B. Conclusions This comparative trial shows that poor responder women undergoing repeated assisted reproduction treatment using modified super-long down-regulation protocol achieve more oocytes, leading to higher fertilization rate, compared to women receiving routine long protocol. Our study also showed that clinical pregnancy rate was significantly improved.
