The Influences of Mg^(2+), Ca^(2+) and Mg ^(2+)/Ca ~ (2+) Ratio in Mixed Seawater on the Emergence Rate of Penaeus japonicus Postlarva

This paper reports the approprite ranges of Mg 2+, Ca 2+ and their ratio Mg 2+/Ca 2+ in mixed seawater for rearing of Penaeus japonicus larvae. The ranges for the above three indices are 1150-1450 mg/L, 360-440 mg/L and 2.8-3.4, respectively. The proper salinity range of mixed seawater is 22.1-33.8 obtained by mixing estuarine water and concentrated seawater.

Effect of soil surface roughness on emergence rate and yield of mechanized direct-seeded rapeseed based on 3D laser scanning

The quality of seedbed after sowing such as soil surface roughness is one of the key factors affecting the seedling emergence of rapeseed,which ultimately affected crop yield.However,the effect of soil surface roughness on seedling emergence and yield of rapeseed is still unclear.In this study,field experiments at the experimental site of Jianli and Shayang were carried out.Three treatments were designed:relative slow(M1),medium(M2),and fast(M3)forward speed of the unit.Soil surface roughness measured by a 3D laser scanner,seed quantity of the seeder,emergence rate and yield of rapeseed were determined to investigate the soil surface roughness effect on emergence rate and yield of rapeseed.The results showed that as the forward speed of the unit increased,the compartment surface became rougher.Compared with the M1 and M2 treatments,soil surface roughness under the M3 treatment increased by 36.5%and 9.8%,respectively.The actual seed quantity of the seeder under different treatments ranged from 3806.56 to 4158.18 g/hm2.The average error rate of the actual and theoretical seed quantity was less than 5%,which met the operational quality requirements for seeding rapeseed crops.As the forward speed of the unit increased,the actual seed quantity of the seeder gradually increased while the emergence rate and yield of rapeseed decreased.The seed quantity under the M3 treatment increased by 6.9%and 4.7%,while the emergence rate of rapeseed decreased by 3.3%and 2.0%,and the yield decreased by 23.2%and 13.1%,compared with the M1 and M2 treatments,respectively.Correlation analysis indicated that emergence rate and yield of rapeseed were negatively influenced by soil surface roughness.Considering rapeseed emergence rate,seed yield,and economic benefits,the M1 treatment was recommended.But considering the factor that the M1 treatment may reduce the unit operation efficiency,and thus resulting in lower cost of production,M2 could be recommended in actual farming.The results of this study laid a theoretical foundation for analyzing the relationship between the seedbed surface quality and seedling emergence and yield.

Biomimetic earthworm dynamic soil looser for improving soybean emergence rate in cold and arid regions

In cold and arid regions,soil moisture content and accumulated temperature were seriously insufficient during spring sowing,which made it difficult for soybean seedling to emerge.Based on the principle of earthworm optimization and improvement of soil structure,this study innovatively designed a biomimetic earthworm dynamic soil looser through bionic design and theoretical calculation.By highly reducing the movement path and mode of earthworm in the soil,the mechanism could improve the soil temperature(ST)and soil moisture content(SMC),and thus greatly improve the soybean emergence rate(SER).In this study,the effects of biomimetic earthworm dynamic soil looser and its design parameters on soil temperature(ST),soil moisture content(SMC)and soybean emergence rate(SER)were investigated by two-factor test,analysis of variance(ANOVA)and Least significant Difference(LSD).Regression analysis was used to establish the mathematical model between design parameters and soybean emergence rate.MATLAB software was used to optimize the model,and the optimal design parameter combination was obtained.The contrast experiments showed that the biomimetic earthworm dynamic soil looser could construct the soil structure more suitable for the cold and arid regions.Compared with rotary blade(RB)and notched disc harrow(DH),biomimetic earthworm dynamic soil looser could increase soil moisture content by 41.30%and 27.50%,respectively.Compared with the notched disc harrow,the soil temperature could be increased by 7.97%.There was no significant difference between the effect of rotary blade on soil temperature(p>0.05).The soybean emergence rate was increased by 25.40%and 20.70%,respectively,compared with that of notched disc harrow and rotary blade.

Cutting Propagation Technique of Pennisetum purpureum Schum

[Objectives]The paper was to study the cutting propagation technique of Pennisetum purpureum Schum and to provide a technical reference for establishing an efficient cutting propagation method.[Methods]Six treatments were set up using P.purpureum cv.Guiminyin and P.purpureum cv.Guimu-1 as test materials,including 1-node oblique insertion,1-node oblique insertion+rooting powder,1-node transverse burial,2-node oblique insertion,2-node oblique insertion+rooting powder and 2-node transverse burial.The following indices were observed and determined for P.purpureum cuttings:emergence rate,rooting rate,root number,longest root length,fresh root weight,plant height,number of tillers,number of leaves,and fresh stem and leaf weight.[Results]In the 2-node cutting+rooting powder treatment,Guiminyin and Guimu-1 exhibited the highest survival rate,root growth indices,and stem and leaf growth indices,with the emergence rates of 94.29%and 90.26%,respectively.The 2-node cutting treatment followed closely behind,while the 1-node cutting treatment had the lowest indices.Under the same treatment,Guimuyin exhibited higher mean values for plant height,number of leaves,fresh stem and leaf weight,longest root length,and fresh root weight compared to Guimu-1.However,it had lower mean number of tillers,and emergence rate and rooting rate of the 1-node cutting treatment compared to Guimu-1.[Conclusions]The P.purpureum cuttings thrived in the 2-node cutting+rooting powder treatment,and the overall cutting effect of Guiminyin was superior to that of Guimu-1.

OsEIL1 and OsEIL2,two master regulators of rice ethylene signaling,promote the expression of ROS scavenging genes to facilitate coleoptile elongation and seedling emergence from soil

Successful emergence from the soil is a prerequisite for survival of germinating seeds in their natural envi-ronment.In rice,coleoptile elongation facilitates seedling emergence and establishment,and ethylene plays an important role in this process.However,the underlying regulatory mechanism remains largely unclear.Here,we report that ethylene promotes cell elongation and inhibits cell expansion in rice coleoptiles,result-ing in longer and thinner coleoptiles that facilitate seedlings emergence from the soil.Transcriptome analysis showed that genes related to reactive oxygen species(ROS)generation are upregulated and genes involved in ROS scavenging are downregulated in the coleoptiles of ethylene-signaling mutants.Further investiga-tions showed that soil coverage promotes accumulation of ETHYLENE INSENSITIVE 3-LIKE 1(OsEIL1)and OsEIL2 in the upper region of the coleoptile,and both OsEIL1 and OsEIL2 can bind directly to the promoters of the GDP-mannose pyrophosphorylase(VTC1)gene OsVTC1-3 and the peroxidase(PRX)genes OsPRX37,OsPRX81,OsPRX82,and OsPRX88 to activate their expression.This leads to increased ascorbic acid content,greater peroxidase activity,and decreased ROS accumulation in the upper region of the coleoptile.Disruption of ROS accumulation promotes coleoptile growth and seedling emergence from soil.Thesendings deepen our understanding of the roles of ethylene and ROS in controlling coleoptile growth,and this information can be used by breeders to produce rice varieties suitable for direct seeding.

Artificial Breeding Technology of Cuban Fly and Its Parasitic Ability on Chilo infuscatellus

[Objective] The artificial breeding technology of Cuban fly （Lixophaga diatraeae） and its parasitic ability on Chilo infuscatellus was studied.[Method] Through artificial inoculation experiment,the effects of different inoculation proportions between maggot and Galleria mellonella larvae on the growth and development of Cuban fly were studied.Through indoor low temperature storage tests,effects of different temperatures on the emergence rate of Cuban fly were studied;and the effects of different ecological conditions （humidity,sunshine） on the emergence rate of Cuban fly and its parasitic ability on Chilo infuscatellus were studied through indoor and field comparison experiment.[Result] The optimum inoculation proportions between maggot and G.mellonella larvae were 3：1 and 4：1,pupa production amounts were 279 and 327,respectively;short storage under the temperature of 10℃ had small effect on the emergence rate of Cuban fly,while the storage time should not exceed 15 d.Indoor and field parasitic test showed that Cuban fly had strong parasitic ability on C.infuscatellus,the parasitic rate reached 33.3%-50.0%;the parasitic rates during elongation stage and maturation stage were 47.8% and 41.7%,respectively,while they almost could not parasite during seedling stage.[Conclusion] The results provided scientific basis for artificial breeding of Cuban fly in large scale and its field release technology.

Study on Seed Breeding of Thuia sutchuenensis

Objective] This research almed to study technical requirements by seed breeding of Thuia sutchuenensis so as to Iay a foundation for the saving and breeding of Thuia sutchuenensis. [Method] The seeds of Thuia sutchuenensis, coI-Iected from Xianyi Town, Chengkou County, Chongqing City, were used as material. The effects of temperature and matrix on germination rate and emergence rate of Thuia sutchuenensis were investigated. In addition, the controI effects of different-type and different-concentration pesticides on seedIing bIight of Thuia sutchuenensis were also studied. [Result] The suitabIe temperature for seed germination of Thuia sutchuenensis was 15-20 ℃, whiIe the optimum temperature was 20 ℃, under which the germination rate couId reach 95%. At temperature of 25 ℃, the seeds of Thuia sutchuenensis almost couId not germinate. The seeds of Thuia sutchuenensis germinated most if soaked in warm water of 40 ℃. After 24 h soaking, the germi-nated seeds were not increased significantIy. Among the matrixes for contalner seedIing, the 18th matrix, composed by sawdust （2/3） and forest topsoiI or general soiI （1/3）, was conducive to the seed germination in contalners. Among the pesti-cides, the controI effect of ferrous suIfate on diseases and pests in Thuia sutchue-nensis was best with cumuIative incidence of 15%, foI owed by those of fe-naminosuIf （17%）, Bordeaux mixture （21%）, KangkuIing （22%） and potassium per-manganate. [Conclusion] Sawdust had great effect on emergence rate of Thuia sutchuenensis in contalner seedIing, which might be reIated to good water retention and permeabiIity of sawdust. However, too much forest soiI was not conducive to the emergence rate of Thuia sutchuenensis in contalner seedIing. Ferrous suIfate had the best controI effect on diseases and pests in Thuia sutchuenensis.

Simulation of temperature distribution in double-row potato ridges mulched with plastic film covered with soil

In Northwest China,potatoes are cultivated on double-rows of each ridge which is mulched with plastic film,and the film is covered with some of soil.While effective in retaining soil moisture,this technique can render the potato seedlings prone to be burned if they are not released from the plastic film in time.In this study,the model of convective heat transfer of potato ridge under solar radiation and atmospheric radiation is established by the Fluent software.The processes of the heat transfer of potato ridge was simulated for a certain day,and the temperature distribution in the potato ridge was monitored over time.The temperature distribution of soil in the growth layer of potato plants was analyzed under different thickness and widths of the covering soil on the film.The results showed that with the increase of covering soil thickness and width,the time for soil at different depth to reach the peak-temperature was delayed,and the daily temperature change of soil where the different depths layer of potato plants growth was reduced.At that time,a binary regression equation of offset temperature was constructed by using the Response Surface Method.The best parameter combination for covering soil on the plastic film is a thickness of 50 mm and a width of 280 mm in the cold and arid areas of Northwest China.However,the offset temperature(PT)first decreased and then almost remained unchanged with the increase of covering soil thickness.Considering the operational efficiency and power consumption of soil covering devices in the field,the unchanged width of the covering soil is 200 mm.The field experiments have shown that a 50 mm thick of soil covering is beneficial for the growth of potato plants and a 200 mm width of soil covering is beneficial for the growth of potato plants.The height of potato plants was 21 cm,and the natural emergence rate of potatoes was 95.8%on June 9,2024.The environment of soil covered could provide theoretical support for the mechanized planting of potatoes.