Study on the Key and Sensitive Stage of Winter Wheat Responses to Water and Nitrogen Coordination

Pot experiments were carried out to study the effect of nitrogen application on winter wheat under different status of soil moisture, so that the key and sensitive stage of winter wheat responses to water and nitrogen coordination were determined. The results showed that the application of N fertilizer was more effective in early stage than in later stage, and at the lower N rates than at the higher N rates under non-irrigated conditions. N treatments had great effect on spikelet bearing number and grain number per spike, but had no effect on 1 000-grain weight; Grain yield and yield component responses to N treatment were greater under irrigated conditions than under non-irrigated conditions. The joining stage was the key and sensitive stage of winter wheat responses to water and nitrogen coordination, and the grain yield, grain number per spike and 1000-grain weight increased, when water and N Fertilizer were applied at this stage. The mechanism is that water and fertilizer supply at joining stage can speed up the growth of above-ground crops, enhance the abilities to absorb and utilize nitrogen fertilizer, and meanwhile, delay the aging of the root and keep the root vigor for a longer period.

A Novel Three-dimensional Mn(Ⅱ) Coordination Polymer Constructed from Biphenyl-3,3',5,5'-tetracarboxylic Acid and Water

The title Mn（Ⅱ） coordination polymer,poly{[heptaaqua-（μ4-bi-phenyl-3,3？,5,5？-tetracarboxylate）-bimanganese（Ⅱ）] pentahydrate},[Mn_2（bpta）（H_2O）_7]_n·5n H_2O（I）,is crystallized from a mixture of biphenyl-3,3？,5,5？-tetracarboxylic acid（H_4bpta） and MnCl_2·4H_2O in waterethanol under room temperature. Its asymmetric unit consists of one and two halves of crystallographically independent Mn（Ⅱ） cations,one fully deprotonated H4 bpta ligand,seven coordinated water molecules and five solvent water as guest molecules. In I,each Mn（Ⅱ） atom is octahedrally coordinated by six oxygen atoms from bpta^（4-） anions and coordinated water molecules. In the Mn（Ⅱ） cations,one half Mn（Ⅱ） ion of them located at a 2-fold axis generating a trinuclear [Mn_3（H_2O）_2（RCOO）_2] linker by μ1,1-O（water） and μ1,3-O,O？（carboxylate） bridges and another half Mn（Ⅱ） ion with an inversion is a mononuclear linker. These neighbouring trinuclear and mononuclear Mn（Ⅱ） cations are linked together by biphenyl-3,3？,5,5？-tetracarboxylates to form a three-dimensional framework with a（42.84） topology of a（4,4）-connected net,in which the positions of the trinuclear [Mn_3（H_2O）_2（R-COO）_2] linker as a 4-connector linking four bpta^（4-） ligands in I reproduce an eagle-shaped arrangement. The polymeric structure exhibits a water channel with an accessible void of 797.1 ？~3,amounting to 15.7% of the total unit-cell volume. Each of the cavities in the network is occupied by solvent water molecules.

Synthesis,Crystal Structure and Photoluminescent Property of a Novel Dy^(3+) Coordination Compound Containing Rare(H_2O)_(22) Clusters

A novel Dy^（3＋） coordination compound,（H_2pipz）（H_3O）[Dy（pydc）_3]·11H_2O（1,pipz = piperazine and H_2pydc = pyridine-2,6-dicarboxylic acid）,has been hydrothermally synthesized and characterized by X-ray single-crystal diffraction,elemental analysis. It is interesting that the packing structure of compound 1 contains 22-core water clusters. Compound 1 is extended into a threedimensional supramolecular structure via O···H···O hydrogen bonding interactions. Furthermore,the luminescent property of compound 1 was also investigated.

Effects of water and salt coordinated regulation at the different growth stages on water consumption and yield of tomato

The objective of this study was to explore the effects of different degrees of water and salt stress on the actual water consumption and soil salt accumulation of tomatoes and the salt tolerance characteristics of tomatoes under brackish water combined with regulated deficit irrigation mode.The greenhouse pot experiment was used to set three influencing factors,the irrigation water salinity S1 was 1.1 g/L(local shallow groundwater),S2 was 2.0 g/L,and S3 was 4.0 g/L,respectively,and different degrees of water deficit(W1 ranged from 65%-75%Field Capacity(FC),W2 ranged from 55%-65%FC,W3 ranged from 45%-55%FC)and seedling stage(T1),blossoming and bearing fruits stage(T2)and mature picking stage(T3).The response of fresh fruit weight,stems and leaves weight,yield and water use efficiency of tomato under water and salt stress were monitored and analyzed.The results showed the coordinated regulation of water and salt can significantly reduce the electrical conductivity of the 0-30 cm soil of the tomato root system.The higher the salinity of irrigation water,the better the salt control effects of the coordinated regulation of water and salt;the coordinated regulation of water and salt at different growth stages had significant effects on the weight of fresh tomato fruits,the weight of stems and leaves and the yield.The salinity of irrigation water was in inverse proportion to the yield of tomatoes;In S1 treatment irrigation(irrigation water salinity was 1.1 g/L)under the mildly regulated deficit in the seedling stage(irrigation water was 55%-65%of the field water capacity)can effectively reduce the irrigation water volume during the whole growth stage while ensuring that there was no significant reduction in yield.The research results provided a scientific and reliable theoretical basis for the increase of local tomato production,the improvement of water use efficiency and the formulation of suitable irrigation patterns.