The El Niño-Southern Oscillation (ENSO) Effects on Cowpea and Winter Wheat Yields in the Semi-Arid Region of the Southern US

Information is limited on the effects of climate variability on cowpea (Vigna unguiculata L.) and winter wheat (Triticum aestivum L.) yields in the semiarid region of the southern US. Using the Decision Support System for Agrotechnology Transfer (DSSAT) crop model and weather data spanning 81 years, we assessed the impact of El Niño-Southern Oscillation (ENSO) on the grain yields of these crops in the Llano Estacado region of the southern US as affected by cowpea and wheat planting dates and N application rate. Simulated results showed that the El Niño phase of ENSO produced about 30% more yields of mono-cropped cowpea than those produced under the La Niña phase, especially with the cowpeas planted in July. The cowpea yields under El Niño were about 10% more than the 81-year average normal yield, whereas those under La Niña were about 20% less. At the N rates of 0, 50, and 100 kg·ha−1, regardless of wheat planting dates, the El Niño years produced, respectively, about 8%, 40%, and 60% higher wheat yields than those produced in the La Niña years, and about 5%, 20%, and 27% more than the 81-year average normal yield. In the La Niña years, the wheat yields at 0, 50, and 100 kg N ha−1 were, respectively, about 5%, 15%, and 20% less than the normal yield with similar N levels. The impact of ENSO on wheat yields under cowpea-wheat double-cropping systems was significant, especially for the wheat crops planted on October 15 (October 30) or later following the cowpea crops planted in June (July). At zero N, the mono-cropped wheat yields were not impacted by ENSO due to N limitation. However, the double-cropped wheat yields were impacted by ENSO even when no N fertilizer was applied due to high soil N status caused by N transfer from cowpea stover residues and roots. Results indicated that management strategies need to be attentive to ENSO forecasts and adjust potential planting dates and N application rates with the ENSO phase to avert risks of crop failure and economic loss.

Exploring the Potential of Cowpea-Wheat Double Cropping in the Semi-Arid Region of the Southern United States Using the DSSAT Crop Model

Information is limited on the potential of double-cropping cowpea (Vigna unguiculata L.) and wheat (Triticum aestivum L.) in the semiarid region of the southern United States. Using the Decision Support System for Agrotechnology Transfer (DSSAT) crop model and weather data of 80 years, we assessed the possibility of cowpea-wheat double-cropping in this region for grain purpose as affected by planting date and N application rate. Results showed that the possibility of double-cropping varied from 0% to 65%, depending on the cropping system. The possibility was less with systems comprising earlier planting dates of wheat and later planting dates of cowpea. Results indicated that cowpea-wheat double-cropping could be beneficial only when no N was applied, with wheat planted on October 15 or later. At zero N, the double-crops of cowpea planted on July 15 and wheat planted on November 30 were the most beneficial of all the 72 double-cropping systems studied. With a delay in planting cowpea, the percentage of beneficial double-cropping systems decreased. At N rates other than zero, fallow-wheat monocropping systems were more beneficial than cowpea-wheat double-cropping systems, and the benefit was greater at a higher N rate. At 100 kg N ha-1, the monocrop of wheat planted on October 15 was the most beneficial of all the 94 systems studied. Results further showed that fallow-wheat yields increased almost linearly with an increase in N rate from 0 to 100 kg∙ha-1. Fallow-wheat grain yields were quadratically associated with planting dates. With an increase in N rate, wheat yields reached the peak with an earlier planting date. Wheat yields produced under monocropping systems were greater than those produced under double-cropping systems for any cowpea planting date. Cowpea yields produced under monocropping systems were greater than those produced under any double-cropping system. The relationship between cowpea grain yields and planting dates was quadratic, with July 1 planting date associated with the maximum yields.

The effects of soil moisture and salinity as functions of groundwater depth on wheat growth and yield in coastal saline soils

In the coastal saline soils,moisture and salinity are the functions of groundwater depth affecting crop growth and yield.Accordingly,the objectives of this study were to:1)investigate the combined effects of moisture and salinity stresses on wheat growth as affected by groundwater depth,and 2)find the optimal groundwater depth for wheat growth in coastal saline soils.The groundwater depths(0.7,1.1,1.5,1.9,2.3,and 2.7 m during 2013-2014(Y1)and 0.6,1.0,1.4,1.8,2.2,and 2.6 m during 2014-2015(Y2))of the field experiment were maintained by soil columns.There was a positive correlation between soil moisture and salinity.Water logging with high salinity(groundwater depth at 0.7 m in Y1 and 0.6 m in Y2)showed a greater decline towards wheat growth than that of slight drought with medium(2.3 m in Y1)or low salinity(2.7 m in Y1,2.2 and 2.6 m in Y2).The booting stage was the most sensitive stage of wheat crop under moisture and salinity stresses.Data showed the most optimal rate of photosynthesis,grain yield,and flour quality were obtained under the groundwater depth(ditch depth)of 1.9 m(standard soil moisture with medium salinity)and 2.3 m(slight drought with medium salinity)in Y1 and 1.8 m(standard soil moisture with medium salinity)and 2.2 m(slight drought with low salinity)in Y2.The corresponding optimal soil relative moisture content and conductivity with the 1:5 distilled water/soil dilution,in the depth of 0-20 cm and 20-40 cm in coastal saline soils,were equal to 58.67-63.07%and 65.51-72.66%in Y1,63.09-66.70%and 69.75-74.72%in Y2;0.86-1.01 dS m^-1 and 0.63-0.77 dS m^-1 in Y1,0.57-0.93 dS m^-1 and 0.40-0.63 dS m^-1 in Y2,respectively.

Effects of nitrogen management on the ratoon crop yield and head rice yield in South USA

Ratoon rice cropping is an important component of the rice cropping system in Texas and south Louisiana,USA,and expanded to Asian countries in 1970.Two field studies were conducted with widely planted rice(Oryza sativa L.)cultivars at Eagle Lake,Texas,USA to determine the effects of nitrogen(N)management in main(first)crop(MC)and ratoon(second)crop(RC)on RC yield.In 2012 and 2013,one cultivar(Presidio)was adopted to determine the effects of RC N management on ratoon yield and head rice yield.In 2016 and 2017,CL153,CL163 and CL272 in addition to Presidio were adopted to examine the effect of MC N management on ratoon yield and head rice yield.N applied at preflood after MC harvest considerably improved RC yield.Application of 99 kg N ha^(–1)at preflood after MC harvest was practically adequate for RC regrowth,development and approaching the yield potential for Presidio.RC could produce quite high average grain yields of 5.90 to 6.53 t ha–1 in 2012 and 2013,respectively.Main crop N rate only significantly affected MC yield;however,given N applied of 99 kg ha^(–1)at preflood after MC harvest,ratoon yield was not significantly affected by MC N rate.Neither the main nor ratoon crop N management had a significant effect on RC head rice yield.Considerable RC head rice yields(55–65%)were observed in all of the four cultivars and 4 years except for CL272 in 2016.These results indicat that without very high N fertilizer application,rice ratoon crop could produce a considerable grain yield and an expectative head rice yield.Rice ratooning could be a practical way to increase rice yields with the minimal input in south Texas and regions with a similar climate.

Straighthead and Agronomy Characters Testing for Selected Parent Lines and Hybrid Combinations at UAPB in 2011-2012

Straighthead disease is a physiological disorder in rice and the most widespread non-fungal disease of the U.S. straighthead greatly reduces rice yield. Straighthead studies were most conducted in the artificial field which was Arsenic amendment plots due to the similarity of straighthead symptoms of Arsenic damage. To evaluate the straighthead disease resistance in natural condition, 46 rice lines, including 24 inbred lines and 22 hybrid combinations which were developed from breading program, were chosen for straighthead and agronomy characters testing in a native soil where straighthead naturally induced in the past years at University of Arkansas at Pine Bluff (UAPB), Arkansas in 2011 and 2012. The straighthead of rice were rated from 0 to 9 levels, and 0 was the least straighthead disorder and 9 was the most severe straighthead disorder. Cocodrie (CCDR) was used as the check in this study. The results of 2011 showed that the yields of 8 entries were higher than the check CCDR. The straighthead scores of these 8 entries were 0 - 1 which indicated their resistance to straighthead. The rest of the entries had lower yields than check CCDR with straighthead scores 5 - 6 which indicated their moderate susceptibility to straighthead. The yields were negatively related to the straighthead scores (r = -0.9178, P < 0.01). The results of 2012 showed that the yields of 9 hybrids and 6 inbred entries were higher than the check CCDR. The straighthead scores of top 12 entries were 0 - 2 which indicated that they were resistant to straighthead and 3 entries with straighthead score of 3 which indicated they were moderately resistant to straighthead. The rest 3 hybrids and 4 inbred entries had lower yields than the check and their straighthead scores were 5 - 6 which indicated their moderately susceptible to straighthead. The yields was negatively related to the straighthead scores (r = -0.956, P < 0.01). Compared to CCDR, the yield of hybrids showed their straighthead resistance at some extent. The yields of top six entries, hybrid 33A/PB23, inbred 3053, hybrid 28s/PB22, 28s/PB24, 29s/PB24 and inbred 3222, were 10,376.4, 9991.4, 9566.7, 9334.3, 9183.9 and 9174.3 Kg/Ha, and 46.0%, 40.7%, 34.7%, 31.4%, 29.3%, and 29.5% higher than the check, respectively.

Assessing Cowpea-Wheat Double Cropping Strategies in the Southern United States Using the DSSAT Crop Model

Information is limited on the potential of cowpea-wheat double cropping in the southern United States to enhance soil health and increase net returns. Using the Decision Support System for Agrotechnology Transfer (DSSAT) crop model and weather data spanning 80 years, we assessed the effects of soil type (Darco: Grossarenic Paleudults and Lilbert: Arenic Plinthic Paleudults), N application rate (0, 100, and 200 kg•ha−1), and El Niño-Southern Oscillation (ENSO) on the grain yields of double-cropped cowpea (Vigna unguiculata L.) and wheat (Triticum aestivum L.) in this region. Yield differences were tested using the pairwise Wilcoxon rank sum test. Results showed that yields of wheat that followed cowpea (cwheat) were greater than those that followed fallow (fwheat). The soil type effects on cwheat and fwheat yields decreased with an increase in N rate. The soil type effect on cowpea yields was greater during La Niña. The ENSO impact on cowpea yields was greater on the less fertile soil Darco. Yields of cwheat and fwheat increased with an increase in N rate up to 100 and 200 kg•ha−1, respectively. The yield response of cwheat to N rate was less than that of fwheat. The N rate effects on cwheat and fwheat yields were greater on Darco and under El Niño. Yields of cowpea were greatest under El Niño, whereas those of wheat were greatest under La Niña. The ENSO effect on cowpea yields was greater on Darco. With an increase in N rate, the effect of ENSO was diminished.

Sex biased expression of hormone related genes at early stage of sex differentiation in papaya flowers

Sex types of papaya are controlled by a pair of nascent sex chromosomes,but molecular genetic mechanisms of sex determination and sex differentiation in papaya are still unclear.We performed comparative analysis of transcriptomic profiles of male and female floral buds at the early development stage before the initiation of reproductive organ primordia at which there is no morphological difference between male and female flowers.A total of 1734 differentially expressed genes(DEGs)were identified,of which 923 showed female-biased expression and 811 showed male-biased expression.Functional annotation revealed that genes related to plant hormone biosynthesis and signaling pathways,especially in abscisic acid and auxin pathways,were overrepresented in the DEGs.Transcription factor binding motifs,such as MYB2,GAMYB,and AP2/EREBP,were enriched in the promoters of the hormone-related DEGs,and transcription factors with those motifs also exhibited differential expression between sex types.Among these DEGs,we also identified 11 genes in the non-recombining region of the papaya sex chromosomes and 9 genes involved in stamen and carpel development.Our results suggested that sex differentiation in papaya may be regulated by multiple layers of regulation and coordination and involved transcriptional,epigenetic,and phytohormone regulation.Hormones,especially ABA and auxin,transcription factors,and genes in the non-recombination region of the sex chromosome could be involved in this process.Our findings may facilitate the elucidation of signal transduction and gene interaction in sex differentiation of unisexual flowers in papaya.

Effects of organic fertilizer with or without a microbial inoculant on the growth and quality of lettuce in an NFT hydroponic system

Organic food continues to increase in popularity worldwide.Similarly,hydroponic production of leafy greens is expanding globally and is an important component of the world's food supply.The purpose of this study was to evaluate the growth and quality of lettuce using six nutrient film technique(NFT)hydroponic systems.There were three treatments:organic fertilizer with or without a microbial inoculant and a conventional inorganic fertilizer as a control.The experiment was repeated over time.Results showed that the plants grown with organic fertilizer with additional microbial inoculant achieved similar shoot fresh and dry weight to those of the control,and dry weight was 17%higher than the organic fertilizer without inoculant.Nitrogen content in the shoot tissue of plants treated with organic fertilizer with inoculant was 10%and 24%greater than the control and the organic fertilizer without inoculant,respectively.However,when the organic fertilizer with inoculant was reused in a second experiment,shoot fresh and dry weight of plants in organic fertilizer with inoculant was lower than those in the control but were still higher compared to the organic fertilizer without inoculant.Additionally,electrical conductivity(EC)and pH of the organic fertilizer solutions fluctuated widely.Interestingly,relative chlorophyll content measured as SPAD and anthocyanin content in the leaf tissue increased in plants treated with organic fertilizer,regardless of inoculant,by 19%and 9%,respectively.

Succinic Acid Production across Candidate Lignocellulosic Biorefinery Feedstocks

Non-food lignocellulosic crops with both high biomass yields and superior adaptation to marginal lands have significant potential as biofuel feedstocks that can replace fossil fuels. Deployment of dedicated crops into single biofuels, however, has been reduced by conversion technology costs and low petroleum prices. Integrated biorefinery strategies, in which value-added coproducts are generated in conjunction with biofuels, by comparison offer opportunities to overcome this economic disadvantage. The objective of this research was to evaluate succinic acid accumulation across candidate lignocellulosic feedstocks. Feedstock entries included pearl millet x napiergrass hybrids (“PMN”;Pennisetum glaucum [L.] R. Br. × P. purpureum Schumach.), napiergrass (P. purpureum Schumach.), annual sorghum (Sorghum bicolor [L.] Moench), pearl millet (P. glaucum [L.] R. Br.), perennial sorghum (Sorghum spp.), switchgrass (Panicum virgatum L.), sunn hemp (Crotalaria juncea L.), giant miscanthus (Miscanthus × giganteus J. M. Greef & Deuter) and energy cane (Saccharum spp. L.). Replicated field plots, as well as an independent greenhouse trial, were characterized for succinic acid content. The PMN, napiergrass, sunn hemp and energy cane entries had greater (P ≤ 0.05) succinic acid yields, up to 556 kg·ha-1, in field trials. Napiergrass and PMN entries similarly had higher succinic acid yields under greenhouse conditions;however, irrigation treatments did not alter succinic acid accumulation in this study. Napiergrass, PMN, and energy cane thus are promising biorefinery feedstocks.

Soil Enzyme Activities and Organic Matter Composition Affected by 26 Years of Continuous Cropping

The study was to determine the long-term effects of subtropical monoculture and rotational cropping systems and fertilization on soil enzyme activities and soil C, N, and P levels. Cropping systems included continuous sorghum(Sorghum bicolor L.), cotton(Gossypium hirsutum L.), corn(Zea mays L.), and cotton/sorghum rotations after 26 years of treatment imposition. Soil under continuous sorghum and continuous corn had 15% and 11%, respectively, greater C concentrations than soil under continuous cotton.Organic C was 10% higher at 0–7.5 cm than at 7.5–15 cm. Total N followed similar trends with soil depth as organic C. Continuous sorghum had 19% higher total N than other crop species and rotations. With fertilization, continuous cotton had the highest total P at 0–7.5 cm and sorghum had the highest at 7.5–15 cm. Soil total P was 14% higher at 0–7.5 than at 7.5–15 cm, and fertilization increased 15% total P compared to unfertilized soil. Arylsulfatase, alkaline phosphatase, and β-d-glucosidase activity were the highest for sorghum and the lowest for cotton. Rotation increased enzyme activities compared to continuous cotton but not for continuous sorghum. Of all crop species and rotations, continuous cotton generally showed the lowest levels of organic matter and enzyme activities after 26 years. Fertilization significantly increased the yields for all cropping systems, but rotation had no significant effect on either sorghum or cotton lint yield compared to each crop grown in monoculture. Long-term cropping did not increase soil organic matter levels beyond short-term gains, indicating the difficulty in promoting C sequestration in subtropical soils.

Co-incorporation of rice straw and leguminous green manure can increase soil available nitrogen(N)and reduce carbon and N losses:An incubation study

Returning rice straw and leguminous green manure alone or in combination to soil is effective in improving soil fertility in South China.Despite the popularity of this practice,our understanding o f the underlying processes for straw and manure combined application is relatively poor.In this study,rice straw(carbon(C)/nitrogen(N)ratio of 63),green manure(hairy vetch,C/N ratio of 14),and their mixtures(C/N ratio of 25 and 35)were added into a paddy soil,and their effects on soil N availability and C or N loss under waterlogged conditions were evaluated in a 100-d incubation experiment.All plant residue treatments significantly enhanced C〇2 and CH4 emissions,but decreased N2O emission.Dissolved organic C(DOC)and N(DON)and microbial biomass C in soil and water-soluble organic C and N and mineral N in the upper aqueous layer above soil were also enhanced by all the plant residue treatments except the rice straw treatment,and soil microbial biomass N and mineral N were lower in the rice straw treatment than in the other treatments.Changes in plant residue C/N ratio,DOC/DON ratio,and cellulose content significantly affected greenhouse gas emissions and active C and N concentrations in soil.Additionally,the treatment with green manure alone yielded the largest C and N losses,and incorporation of the plant residue mixture with a C/N ratio of 35 caused the largest net global warming potential(nGWP)among the amended treatments.In conclusion,the co-incorporation of rice straw and green manure can alleviate the limitation resulting from only applying rice straw(N immobilization)or the sole application of leguminous green manure(high C and N losses),and the residue mixture with a C/N ratio of 25 is a better option because of lower nGWP.

LOWER TEMPERATURE 1 Enhances ABA Responses and Plant Drought Tolerance by Modulating the Stability and Localization of C2-Domain ABA-Related Proteins in Arabidopsis

Plasma membrane-associated abscisic acid(ABA)signal transduction is an integral part of ABA signaling.The C2-domain ABA-related(CAR)proteins play important roles in the recruitment of ABA receptors to the plasma membrane to facilitate ABA signaling.However,how CAR proteins are regulated remains unclear.In this study,we conducted a genetic screen for mutants with altered leaf transpiration and identified an uncharacterized protein,LOWER TEMPERATURE 1(LOT1),which regulates the dynamic localization and stability of CAR proteins.The lotimutant had a lower leaf temperature as compared with the wild type due to higher transpiration.We found that LOT1 physically interacts with CAR9,and ABA reduces LOT1-CAR9 interaction in the nucleus,likely via Ca^2+,resulting in increased localization of CAR9 to the plasma membrane.We further found that the stability of CAR9 is affected by LOT1 less CAR9 proteins were accumulated and more were ubiquitinated in lot1.While the lot1 car9 and/of f car9 mutants were hyposerisitive to ABA,the hyposensitive phenotype of loticould be rescued by CAR9 overexpression.Collectively,our study reveals that LOT1 regulates plant tolerance to drought stress by affecting ABA signaling through regulating the stability and dynamic localization of CAR9.

Soil Organic Carbon Pools Under Switchgrass Grown as a Bioenergy Crop Compared to Other Conventional Crops

Switchgrass (Panicum virgatum L.) has been proposed as a sustainable bioenergy crop because of its high yield potential, adaptation to marginal sites, and tolerance to water and nutrient limitations. A better understanding of the potential effects of biomass energy crop production practices on soil biological properties and organic matter dynamics is critical to its production. Our objective was to evaluate changes in C pools under a warm-season perennial switchgrass in different soils compared to typically-grown crops collected at College Station, Dallas, and Stephenville, TX in February 2001. Sampling depths were 0-5, 5-15, and 15-30 cm. Switchgrass increased soil organic C (SOC), soil microbial biomass C (SMBC), mineralizable C, and particulate organic matter C (POM-C) compared to conventional cropping systems. Soil C concentrations were in the order: long-term coastal bermudagrass [Cynodon dactylon (L.) Pers.]> switchgrass or kleingrass (Panicum coloratum L.) planted in 1992> switchgrass 1997> conventional cropping systems. Soil C concentrations tended to increase with increasing clay content. Greater microbial biomass C followed the order of Dallas> College Station> Stephenville, and ranged from approximately 180 mg C kg-1 soil at Stephenville to 1 900 mg C kg-1 soil at Dallas. Particulate organic C was more sensitive than other fractions to management, increasing as much as 6-fold under long-term coastal bermudagrass compared to conventional cropping systems. Our study indicated that conversion of conventional cropping systems into switchgrass production can sequestrate more SOC and improve soil biological properties in the southern USA.

PBS3 Protects EDS1 from Proteasome-Mediated Degradation in Plant Immunity

Plant immunity is controlled by both positive regulators such as PBS3 and EDS1 and negative regulators such as NPR3 and NPR4.However,the relationships among these important immune regulators remain elusive.In this study,we found that PBS3 interacts with EDS1 in both the cytoplasm and the nucleus,and is required for EDS1 protein accumulation?NPR3 and NPR4,which function as salicylic acid receptors and adaptors of Cullin3-based E3 ligase,interact with and mediate the degradation of EDS1 via the 26S proteasome.We further discovered that PBS3 inhibits the polyubiquitination and subsequent degradation of EDS1 by reducing the association of EDS1 with the Cullin3 adaptors NPR3 and NPR4.Furthermore,we showed that PBS3 and EDS1 also contribute to PAMP-triggered immunity in addition to effector-triggered immunity.Collectively,our study reveals a novel mechanism by which plants fine-tune defense resporises by inhibiting the degradation of a positive player in plant immunity.

Coordinated regulation of plant immunity by poly(ADP-ribosyl)ation and K63-linked ubiquitination

Poly(ADP-ribosyl)ation(PARylation)is a posttranslational modification reversibly catalyzed by poly(ADP-ribose)polymerases(PARPs)and poly(ADP-ribose)glycohydrolases(PARGs)and plays a key role in multi-ple cellular processes.The molecular mechanisms by which PARylation regulates innate immunity remain largely unknown in eukaryotes.Here we show that Arabidopsis UBC13A and UBC13B,the major drivers of lysine 63(K63)-linked polyubiquitination,directly interact with PARPs/PARGs.Activation of pathogen-associated molecular pattern(PAMP)-triggered immunity promotes these interactions and enhances PARylation of UBC13.Both parp1 parp2 and ubc13a ubc13b mutants are compromised in immune responses with increased accumulation of total pathogenesis-related(PR)proteins but decreased accu-mulation of secreted PR proteins.Protein disulfide-isomerases(PDIs),essential components of endo-plasmic reticulum quality control(ERQC)that ensure proper folding and maturation of proteins destined for secretion,complex with PARPs/PARGs and are PARylated upon PAMP perception.Significantly,PARylation of UBC13 regulates K63-linked ubiquitination of PDIs,which may further promote their disulfide isomerase activities for correct protein folding and subsequent secretion.Taken together,these results indicate that plant immunity is coordinately regulated by PARylation and K63-linked ubiquitination.

NLR immune receptor RB is differentially targeted by two homologous but functionally distinct effector proteins

Plant nucleotide-binding leucine-rich repeat(NLR)receptors mediate immune responses by directly or indirectly sensing pathogen-derived effectors.Despite significant advances in the understanding of NLR-mediated immunity,the mechanisms by which pathogens evolve to suppress NLR activation triggered by cognate effectors and gain virulence remain largely unknown.The agronomically important immune receptor RB recognizes the ubiquitous and highly conserved IPI-O RXLR family members(e.g.,IPI-O1)from Phytophthora infestans,and this process is suppressed by the rarely present and homologous effector IPIO4.Here,we report that self-association of RB via the coiled-coil(CC)domain is required for RB activation and is differentially affected by avirulence and virulence effectors.IPI-O1 moderately reduces the self-association of RB CC,potentially leading to changes in the conformation and equilibrium of RB,whereas IPIO4 dramatically impairs CC self-association to prevent RB activation.We also found that IPI-O1 associates with itself,whereas IPI-O4 does not.Notably,IPI-O4 interacts with IPI-O1 and disrupts its self-association,therefore probably blocking its avirulence function.Furthermore,IPI-O4 enhances the interaction between RB CC and IPI-O1,possibly sequestering RB and IPI-O1 and subsequently blocking their interactions with signaling components.Taken together,these findings considerably extend our understanding of the underlying mechanisms by which emerging virulent pathogens suppress the NLR-mediated recognition of cognate effectors.

可应用于农药喷洒及农田灌溉的多用途气悬浮车设计

农药喷洒和农田灌溉是现代农业生产中最重要的管理措施,是确保作物正常生长发育和高产的重要因素。然而,病虫草害的有效防控及灌溉水的高效利用仍然是困扰中国农业生产的迫切难题。在中国,当前落后的农药施用及灌溉技术需要大量的农药及灌溉水被应用于农业生产中,造成资源有效利用率低,限制农作物产量和品质进一步提升,从而影响农作物生产及农业产业发展。目前,机械化农药施用及灌溉系统为农业生产和可持续发展带来了一定影响,尤其是航空喷药及灌溉技术,有利于提高农业资源利用率,实现大面积化农药施用及灌溉的精准操作。遥控式小型无人机已在此领域得到初步应用,通过手动智能操控遥控器及GPS定位,使其旋翼产生的向下气流辅助增加气流对作物的穿透性来实现,具有操作灵活、自动控制能力强及避免飘移等特点。然而现有无人机动力单一,应用范围有限,造价成本偏高。相对而言,悬浮飞行设备动力充足,功率较大,飞行速度较快,对载重量大且远距离的商业及工业运行带来很大便捷,但现有悬浮飞行设备均采用化学燃料作为动力源,造成污染环境,且现有悬浮飞行设备结构复杂,操控难度大,用途有限,还未见关于悬浮飞行设备在农业生产中得以应用的报道。为弥补现有航空技术存在的不足,我们发明了一种可应用于农药喷洒及农田灌溉的多用途气悬浮车。该新型气悬浮车采用蓄电池作为动力源,车体的底部设置有四个车轮,车体的顶部设置有螺旋桨,尾部电机驱动设置于车体尾部的尾部叶轮转动,车体的左右分别设置有第一电机和第二电机,变阻器用于调节各个电机的转速,车体内的前侧设置有控制方向杆和控制速度踏板,控制方向杆上设置有用于控制顶部电机和尾部电机转速的开关,控制方向杆的底部与车轮中的前轮连接,控制方向杆和尾部电机之间通过链条连接,通过转动控制方向杆带动尾部电机转动,使尾部叶轮的轴向发生变化,控制速度踏板与第一电机和第二电机的变阻器连接,控制速度踏板调整变阻器的滑动位置。此多用途气悬浮车采用将电能转化为机械能的原理,通过多部电动机提供动力源,弥补了现有无人机和悬浮飞行设备动力单一,结构复杂,不易操控,用途有限,成本较高及污染环境等不足。其原理独特,设计巧妙,结构简单,成本较低,便于操控,用途多样,便捷、安全且环保,在现代农业生产中具有广阔的推广应用前景。

Growth,nutritional quality,and energy use efficiency in two lettuce cultivars as influenced by white plus red versus red plus blue LEDs

Red plus blue light-emitting diodes(LEDs)are commonly applied in plant factories with artificial lighting due to photosynthetic pigments,which absorb strongly in red and blue light regions of the spectrum.However,plants grown under natural environment are used to utilizing broad-wide spectrum by long-term evolution.In order to examine the effects of addition light added in red plus blue LEDs or white LEDs,green and purple leaf lettuces(Lactuca sativa L.cv.Lvdie and Ziya)were hydroponically cultivated for 20 days under white LEDs,white plus red LEDs,red plus blue LEDs,and red plus blue LEDs supplemented with ultraviolet,green or far-red light,respectively.The results indicated that the addition of far-red light in red plus blue LEDs increased leaf fresh and dry weights of green leaf lettuce by 28%and 34%,respectively.Addition of ultraviolet light did not induce any differences in growth and energy use efficiency in both lettuce cultivars,while supplementing green light with red plus blue LEDs reduced the vitamin C content of green leaf lettuce by 44%and anthocyanin content of purple leaf lettuce by 30%compared with red plus blue LEDs,respectively.Spectral absorbencies of purple leaf lettuce grown under red plus blue LEDs supplemented with green light were lower in green light region compared with those grown under red plus blue LEDs,which was associated with anthocyanin contents.White plus red LEDs significantly increased leaf fresh and dry weights of purple leaf lettuce by 25%,and no significant differences were observed in vitamin C and nitrate contents compared with white LEDs.Fresh weight,light and electrical energy use efficiencies of hydroponic green and purple leaf lettuces grown under white plus red LEDs were higher or no significant differences compared with those grown under red plus blue LEDs.In conclusion,white plus red LEDs were suggested to substitute for red plus blue LEDs in hydroponic lettuce(cv.Lvdie and Ziya)production in plant factories with artificial lighting.