Effects of Plant Spacing,Row Spacing and Seedling Number Allocation on the Growth Dynamics of Different Populations of Two Types of Rice Varieties

[Objectives]This study was conducted to construct high-yielding,high-quality,and high-light-efficiency population structures of different types of rice varieties.[Methods]The effects of plant spacing,row spacing and seedling number allocation on stems and tillers,leaf area and dynamic traits of high-yielding rice populations(more than 9750 kg/hm^(2))and low-yielding populations(less than 9750 kg/hm^(2))were studied by two kinds of representative rice varieties with different tiller ability and panicle sizes in cold regions.[Results]Decreasing the plant and row spacing and increasing the number of planted seedlings per hole advanced the heading date and made the number of stems and tillers in the population increase.The impact on the super rice variety with fewer tillers and heavier panicles was greater than that of conventional variety with more tillers and lighter panicles.The stems and tillers of the high-yielding high-quality populations grew steadily in the early stage of development,until an appropriate number of panicles was reached at the critical leaf age for productive tillers(June 25),and the peak seedlings should appear in the jointing stage(July 9)with a small number(that value of Longjing 21,the super rice variety with fewer tillers and heavier panicles,was about 1.2 times the expected panicle number,and that of the conventional variety with more tillers and lighter panicles,Kongyu 131,was about 1.1 times the expected panicle number).The populations gradually declined since then,until reaching an appropriate number of panicles at the heading stage.The high-yielding high-quality populations had a higher leaf area index at the heading stage.The value of Longjing 21,the super rice variety with fewer tiller and heavier panicles,reached about 6.0,and that of Kongyu 131,the conventional variety with more tillers and lighter panicles,reached about 4.5.The values decreased thereafter.At the maturation stage,the leaf area index of Longjing 21 remained above 2.5,and that of Kongyu 131 remained above 2.0.[Conclusions]This study has an important guiding role and significance for their high-yielding and high-quality supporting cultivation in cold regions.

Model tests for surge height of rock avalanche–debris flows based on momentum balance

Rock avalanche–debris flows triggered by earthquakes commonly take place in mountainous areas.When entering a body of water,due to good fluidity they can move for some time instead of halting in water.In this study,we proposed a method for calculating the surge height of rock avalanche–debris flows based on momentum balance and designed a series of model tests to validate this method.The experimental variables include the initial water depth,landslide velocity,and landslide volume.According to the experimental results,we analyzed the maximum wave height in sliding zone based on momentum balance.In addition,we investigated the surge height and proposed the calculation method in propagating zone and running up zone.In this way,we can find out the surge height in different areas when a rock avalanche–debris flow impacts into the water,which could provide a basis for analyzing the burst of barrier lakes.

Comparisons of Protein Composition of Grains at Different Positions in Panicles between Erect and Curved Panicle Type Japonica Rice

Under field conditions,three erect panicle type japonica rice cultivars and three curved panicle type japonica rice cultivars were applied as experimental materials to investigate the differences of protein composition of grains at different positions in panicles between two different panicle types of japonica rice. According to the results,the panicle type of japonica rice had no direct correlation with albumin content,globulin content,prolamin content and glutelin content in rice,variations of protein composition of grains at different positions in panicles. There were certain correlations between soluble protein contents at different grain positions in the same panicle and the flowering order of glumous flowers in the panicle. Albumin content,prolamin content and glutelin content in grains on secondary rachis branches of two panicle types( erect and curved) of japonica rice cultivars were higher than that on primary rachis branches,while globulin content exhibited an opposite trend. Globulin content,prolamin content and glutelin content in grains at different positions demonstrated a descending order of bottom > middle >top,while albumin content exhibited an opposite trend. The interactions between primary and secondary rachis branches and among top,middle and bottom rachis branches significantly affected soluble protein contents.

Experimental Study on Water Saving of Large-scale Mechanized Paddy Field Production Process in Heilongjiang Province

In order to clarify the water-saving technologies and standards in large-scale mechanized production of paddy fields, the water-saving effects and cost-benefit situations of paddy field steeping, seedling transplanting and different land preparation methods were studied. The results showed that the suitable water layer height for the closing period of mechanized operation was 10 cm, which could save water, facilitate weed control, and lead to better effect and the highest yield. The treatment with a water layer height of 1 cm(Huadashui) for the seedling planting operation achieved better quality of seedling transplanting, lower vacancy rate and higher yield and was water-saving. From the perspective of saving water and taking into account the cost of land preparation, the method of steeping and beating the field was better than the method of plowing in autumn and rotary tillage and harrowing in spring, but it was very prone to lodging. From the perspective of high yield creation, the method of plowing in autumn and rotary tillage and harrowing in spring was significantly better than the method of steeping and beating the field. In order to reduce the cost of land preparation, it is recommended to change the way of plowing in autumn and rotary tillage and hallowing in spring to plowing in autumn and rotary tillage in spring or plowing and hallowing in spring to reduce the cost of one time of rotary tillage, and to simultaneously realize deeper plough layer, which is conducive to preventing lodging and obtaining high yield.

Divergent expression of Neurl3 from hemogenic endothelial cells to hematopoietic stem progenitor cells during development

Prior to the generation of hematopoietic stem cells(HSCs)from the hemogenic endothelial cells(HECs)mainly in the dorsal aorta in midgestational mouse embryos,multiple hematopoietic progenitors including erythro-myeloid progenitors and lymphoid progenitors are generated from yolk sac HECs.These HSCindependent hematopoietic progenitors have recently been identified as major contributors to functional blood cell production until birth.However,little is known about yolk sac HECs.Here,combining integrative analyses of multiple single-cell RNA-sequencing datasets and functional assays,we reveal that Neurl3-EGFP,in addition to marking the continuum throughout the ontogeny of HSCs from HECs,can also serve as a single enrichment marker for yolk sac HECs.Moreover,while yolk sac HECs have much weaker arterial characteristics than either arterial endothelial cells in the yolk sac or HECs within the embryo proper,the lymphoid potential of yolk sac HECs is largely confined to the arterial-biased subpopulation featured by the Unc5b expression.Interestingly,the B lymphoid potential of hematopoietic progenitors,but not for myeloid potentials,is exclusively detected in Neurl3-negative subpopulations in midgestational embryos.Taken together,these findings enhance our understanding of blood birth from yolk sac HECs and provide theoretical basis and candidate reporters for monitoring step-wise hematopoietic differentiation.

Passively-targeted mitochondrial tungsten-based nanodots for efficient acute kidney injury treatment

Acute kidney injury(AKI)can lead to loss of kidney function and a substantial increase in mortality.The burst of reactive oxygen species(ROS)plays a key role in the pathological progression of AKI.Mitochondrial-targeted antioxidant therapy is very promising because mitochondria are the main source of ROS in AKI.Antioxidant nanodrugs with actively targeted mitochondria have achieved encouraging success in many oxidative stress-induced diseases.However,most strategies to actively target mitochondria make the size of nanodrugs too large to pass through the glomerular system to reach the renal tubules,the main damage site of AKI.Here,an ultra-small Tungsten-based nanodots(TWNDs)with strong ROS scavenging can be very effective for treatment of AKI.TWNDs can reach the tubular site after crossing the glomerular barrier,and enter the mitochondria of the renal tubule without resorting to complex active targeting strategies.To our knowledge,this is the first time that ultra-small negatively charged nanodots can be used to passively target mitochondrial therapy for AKI.Through in-depth study of the therapeutic mechanism,such passive mitochondria-targeted TWNDs are highly effective in protecting mitochondria by reducing mitochondrial ROS and increasing mitophagy.In addition,TWNDs can also reduce the infiltration of inflammatory cells.This work provides a new way to passively target mitochondria for AKI,and give inspiration for the treatment of many major diseases closely related to mitochondria,such as myocardial infarction and cerebral infarction.