ABSTRACT
This study was conducted to reveal the effects of silicon (Si) application on nutrient utilization efficiency by rice and on soil nutrient availability and soil microorganisms in a hybrid rice double-cropping planting system. A series of field experiments were conducted during 2017 and 2018. The results showed that Si nutrient supply improved grain yield and the utilization rates of nitrogen (N) and phosphorus (P) to an appropriate level for both early and late plantings, reaching a maximum at 23.4 kg/ha Si. The same trends were found for the ratios of available N (AN) to total N (TN) and available P (AP) to total P (TP), the soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass phosphorus (MBP), and the ratios of MBN to TN and MBP to TP, at different levels of Si. Statistical analysis further revealed that Si application enhanced rice growth and increased the utilization rate of fertilizer due to an ecological mechanism, i.e., Si supply significantly increased the total amount of soil microorganisms in paddy soil compared to the control. This promoted the mineralization of soil nutrients and improved the availability and reserves of easily mineralized organic nutrients.
ABSTRACT
Objective:To explore the correlation between the occurrence of colorectal cancer and different internal environment （cold and heat）. Method:The 70 Wistar rats （male and female） were randomly divided into blank group （10 cases）， cold model group （30 cases） and heat model group （30 cases）. The cold syndrome model was made by intragastric infusion of cold water （0 ℃） and soaking in cold water （10 ℃）. The heat model was made by ethanol （30%） and capsaicin solution （0.9 g·L-1）. The blank group was given normal saline by gavage， 10 mL·kg-1·d-1， for 5 consecutive weeks. The colorectal cancer model was made by subcutaneous injection of DMH solution in the back of neck in the cold model group and heat model group at the 6th week， 25 mg·kg-1，once a week，for 12 consecutive times. During the carcinogenesis， only 30% ethanol solution was given to the heat model group， and the modeling was maintained in cold model group， 10 mL·kg-1·d-1， for 38 weeks. The general state of the rats in each group was observed， and the changes of food intake and body weight were measured. At the 27th， 29th， 32th， 35th and 38th weeks， samples were collected in batches. Intestinal tissues were subjected to hematoxylin-eosin staining （HE） and detection of sodium， potassium-adenosine triphosphate （Na+ K+-ATP）， calcium， magnesium-adenosine triphosphate （Ca2+ Mg2+-ATP） activity， lactate dehydrogenase （LDH） activity and succinate dehydrogenase （SDH） activity. Result:The symptoms of hematochezia and ascites in cold model group were earlier than those in heat model group. As compared with the blank group， the food intake and body weight were decreased in cold model group and heat model group. As compared with the blank group， the length of the large intestine was shorter in cold model group at the 32nd and 35th week （P<0.05）， the activities of Na+ K+-ATP， Ca2+ Mg2+-ATP increased significantly in heat model group at the 27th， 29th and 38th week （P<0.05， P<0.01）， the SDH enzyme activity was decreased in the cold model group at the 29th and 35th week （P<0.05， P<0.01）， the SDH enzyme activity was significantly increased in the heat model group at the 38th week （P<0.01）. At the 27th week， LDH enzyme activity was significantly reduced in cold model group （P<0.01）. The LDH activity was increased significantly in heat model group at 29th and 32nd week （P<0.05， P<0.01）. As compared with the heat model group， the large intestine texture of the cold model rats showed greater brittleness， aggravated fibrosis， more obvious fibroproliferative characteristics， higher tumor incidence， and more serious tumor differentiation. The Na+ K+-ATP， Ca2+ Mg2+-ATP enzyme activities of the cold model rats were significantly reduced at 27th， 29th， and 38th weeks （P<0.01）， the SDH enzyme activity was significantly reduced in the cold model rats at 29th and 38th weeks （P<0.01）， the LDH activity was reduced in the cold model group at 32nd week （P<0.05）. Conclusion:Cold environment for colorectal cancer promotes tumorigenesis， and the hot environment can also promote tumorigenesis in a later stage.