Molecular mechanisms of stress resistance in sorghum: Implications for crop improvement strategies

Abiotic stresses, such as drought, salt, extreme temperatures, and heavy metal pollution, are the main environmental factors that limit crop growth and yield. Sorghum, a C4 grass plant with high photosynthetic efficiency, can grow in adverse environmental conditions due to its excellent stress resistance characteristics. Therefore, unraveling the stress-resistance mechanism of sorghum could provide a theoretical basis for developing and cultivating various stress-resistant crops. This understanding could also help to create a conducive environment for using marginal soil in agriculture and ensuring food security. In this review, we discuss the adaptation mechanisms of sorghum under drought, salinity, temperature, and soil heavy metal stresses, the specific response to stress, the screening of sorghum-resistant germplasm, and the identification and functional analysis of the relevant genes and quantitative trait loci(QTL). In addition, we discuss the application potential of different stress-tolerant sorghum germplasms reported to date and emphasize the feasibility and potential use in developing and promoting highly stress-tolerant sorghum in marginal soil.

A telomere-to-telomere genome assembly of Hongyingzi,a sorghum cultivar used for Chinese Baijiu production

Sorghum(Sorghum bicolor(L.)Moench)is a world cereal crop used in China for producing Baijiu,a distilled spirit.We report a telomere-to-telomere genome assembly of the Baijiu cultivar Hongyingzi,HYZ-T2T,using ultralong reads.The 10 chromosome pairs contained 33,462 genes,of which 93%were functionally annotated.The 20 telomeres and 10 centromeric regions on the HYZ-T2T chromosomes were predicted and two consecutive large inversions on chromosome 2 were characterized.A 65-gene reconstruction of the metabolic pathway of tannins,the flavor substances in Baijiu,was performed and may advance the breeding of sorghum cultivars for Baijiu production.

Comparison of CWSI and T_(s)-T_(a)-VIs in moisture monitoring of dryland crops(sorghum and maize)based on UAV remote sensing

Monitoring agricultural drought using remote sensing data is crucial for precision irrigation in modern agriculture.Utilizing unmanned aerial vehicle(UAV)remote sensing,we explored the applicability of an empirical crop water stress index(CWSI)based on canopy temperature and three-dimensional drought indices(TDDI)constructed from surface temperature(T_(s)),air temperature(T_(a))and five vegetation indices(VIs)for monitoring the moisture status of dryland crops.Three machine learning algorithms(random forest regression(RFR),support vector regression,and partial least squares regression)were used to compare the performance of the drought indices for vegetation moisture content(VMC)estimation in sorghum and maize.The main results of the study were as follows:(1)Comparative analysis of the drought indices revealed that T_(s)-T_(a)-normalized difference vegetation index(TDDIn)and T_(s)-T_(a)-enhanced vegetation index(TDDIe)were more strongly correlated with VMC compared with the other indices.The indices exhibited varying sensitivities to VMC under different irrigation regimes;the strongest correlation observed was for the TDDIe index with maize under the fully irrigated treatment(r=-0.93).(2)Regarding spatial and temporal characteristics,the TDDIn,TDDIe and CWSI indices showed minimal differences Over the experimental period,with coefficients of variation were 0.25,0.18 and 0.24,respectively.All three indices were capable of effectively characterizing the moisture distribution in dryland maize and sorghum crops,but the TDDI indices more accurately monitored the spatial distribution of crop moisture after a rainfall or irrigation event.(3)For prediction of the moisture content of single crops,RFR models based on TDDIn and TDDIe estimated VMC most accurately(R^(2)>0.7),and the TDDIn-based model predicted VMC with the highest accuracy when considering multiple-crop samples,with R^(2)and RMSE of 0.62 and 14.26%,respectively.Thus,TDDI proved more effective than the CWSI in estimating crop water content.

Effect of Planting Date on Yield and Yield Components of Grain Sorghum Hybrids

In Kansas, productivity of grain sorghum [Sorghum bicolor (L.) Moench] is affected by weather conditions at planting and during pollination. Planting date management and selection of hybrid maturity group can help to avoid severe environmental stresses during these sensitive stages. The hypothesis of the study was that late May planting improves grain sorghum yield and yield components compared with late June planting. The objectives of this research were to investigate the influence of planting dates yield and yield components of different grain sorghum hybrids, and to determine the optimal planting date and hybrid combination for maximum biomass and grains production. Three sorghum hybrids (early, medium, and late maturing) were planted in late May and late June without irrigation in Kansas at Manhattan/Ashland Bottom Research Station, and Hutchinson in 2010;and at Manhattan/North Farm and Hutchinson in 2011. Data on dry matter production, yield and yield components were collected. Grain yield and yield components were influenced by planting date depending on environmental conditions. At Manhattan (2010), greater grain yield, number of heads per plant, were obtained with late-June planting compared with late May planting, while at Hutchinson (2010) greater yield was obtained with late May planting for all hybrids. The yield component most affected at Hutchinson was the number of kernels∙panicle−1 and plant density. Late-May planting was favorable for late maturing hybrid (P84G62) in all locations. However, the yield of early maturing hybrid (DKS 28-05) and medium maturing hybrid (DKS 37-07) was less affected by delayed planting. The effects of planting dates on yield and yield components of grain sorghum hybrids were found to be variable among hybrid maturity groups and locations.

Legume Green Manure and Intercropping for High Biomass Sorghum Production

Before the advent of cheap, synthetic fertilizers, legumes were commonly used as green manure crops for their ability to fix atmospheric nitrogen (N). A three-year study at Overton, TX examined legume integration into high-biomass sorghum (Sorghum bicolor L.) production systems on a Lilbert loamy fine sand recently cultivated after a fertilized bermudagrass [Cynodon dactylon (L.) Pers.] pasture. In this split-split plot design, ‘Dixie’ crimson clover (Trifolium incarnatum L.) and ‘Iron and Clay’ cowpea (Vigna unguiculata L.) were integrated into a high-biomass sorghum production system to evaluate impacts on N concentration, C concentration, and yield of high-biomass sorghum and their impacts on soil total N and soil organic carbon (SOC). Main plots were split into crimson clover green manure (CLGM) and winter fallow (FALL) followed by three sub-plots split into warm-season crop rotations: cowpea green manure (CPGM), cowpea-sorghum intercrop (CPSR), and sorghum monocrop (SORG). Three N fertilizer treatments (0, 45, 90 kg N∙ha−1) were randomized and applied as sub-sub plots. The CLGM increased (P sorghum biomass yield (16.5 t DM∙ha−1) 28% in year three but had no effect in the first two years. The CPSR treatment reduced sorghum yield up to 62% compared to SORG;whereas CPGM increased sorghum yield 56% and 18% the two years following cowpea incorporation. Rate of N fertilizer had no effect on sorghum biomass yield. Decrease in SOC and soil N over time indicated mineralization of organic N and may explain why no N fertilizer response was observed in sorghum biomass yield. Cowpea showed strong potential as a green manure crop but proved to be too competitive for successful intercropping in high-biomass sorghum production systems.

Effect of Supplementary Irrigation on the Yield of Sorghum (Sorghum bicolor L. Moench) in the Context of Climate Change in the Dry Savannahs of Togo

Under the current context of climate change, supplementary irrigation may be needed for crop production resilience. We determined the effects of supplementary irrigation on sorghum grain yield in the dry Savannah region of Togo. A two-year trial was conducted in a controlled environment at AREJ, an agro-ecological center in Cinkassé. The plant material was sorghum variety Sorvato 28. The experimental design was a Completely Randomized Block with three replications and three treatments as follows: T0 control plot (rainfed conditions);T1 (supplementary irrigation from flowering to grain filling stage) and T2 (supplementary irrigation from planting to grain filling stage). Two irrigation techniques (furrow and Californian system) were used under each watering treatment. The results showed that irrigation technique significantly affected panicle length with no effect on 1000 grains mass. Panicle length and grain yields varied from 15.59 to 25.71 cm and 0.0 to 2.06 t∙h−1, respectively, with the highest values (25.66 cm and 2.06 t∙h−1, respectively) under the T2 treatment with the California system-based supplementary irrigation. The comparison of results obtained on treatment T0 and T2, shows that supplementary irrigation increased the yields by at least 68.62%. Supplementary irrigation during sowing and growing season (T2) improved sorghum yields in the dry savannahs of Togo, with a better performance of the California irrigation system.

A Survey of the Major Sorghum Production Regions for Foliar and Panicle Diseases during the 2022 Growing Season in Senegal, West Africa

Sorghum is a vital commodity and greatly contributes to the daily calorie needs for millions of the inhabitants in Senegal, West Africa. Yet, sorghum productivity and profitability are impacted by diseases. In the 2022 growing season, 122 farmers’ fields across 7 regions, notably Diourbel, Fatick, Kaffrine, Kaolack, Kolda, Tambacounda, and Thies were surveyed for foliar and panicle diseases. During the survey, stops were made at 30 km intervals and at each stop, 2 - 5 fields were evaluated. In each field, 40 plants mostly at soft to early hard dough stages of development were assessed using a W-shaped pattern to cover the whole field. A total of 13 diseases, including leaf blight, anthracnose, Zonate leaf spot, Sooty stripe, rough leaf spot, oval leaf spot, long smut, grain mold, and covered kernel smut were documented. The most predominant diseases were leaf blight, anthracnose, and zonate leaf spot. The prevalence of leaf blight was 100%, while anthracnose and zonate leaf spot were found in 93 out of the 122 fields surveyed, indicating a 76% prevalence, respectively. Across the regions, the prevalence of rough leaf spot was 47%, covered kernel smut (32%), oval leaf spot (19%) and target leaf spot (19%). Mean incidence of leaf blight was high in all regions, ranging from 94% (Kaolack) to 100% (Fatick and Tambacounda). The highest mean incidence of anthracnose (62%) and covered kernel smut (16%) was noted in Tambacounda region. In the region of Thies, the highest mean incidence of zonate leaf spot (49%) was recorded. The mean severity of leaf blight (37%) was highest on plants assessed in the region of Kaffrine, followed by those in the regions of Kaolack, Tambacounda, and Kolda. Anthracnose infection was most intense on plants evaluated in Kolda, while zonate leaf spot was most severe in the region of Tambacounda. Fields with incidences of 85% and above were considered as “hotspots” to evaluate sorghum germplasm for disease resistance. This survey is significant because the information obtained will be beneficial to plant pathologists, sorghum producers, government officials, and funding agencies to prioritize research projects that ensure productivity and food security.

Reaction of Sorghum Differentials to Grain Mold Infection in Puerto Rico

Grain mold, associated with many fungi, is the most important disease of sorghum, causing both yield and quality losses. In this study, 23 sorghum differentials used in pathotype characterization of anthracnose and head smut pathogens were evaluated for grain mold resistance under favorable conditions in Isabela, Puerto Rico. Lines BTx643 and IS18760 exhibited the lowest grain mold severity, indicating that these two may possess genes for grain mold resistance. These two lines also recorded the highest germination rates 94.7% and 97.6%, respectively, and their seed weight was among the heaviest. In conclusion, these two lines can be utilized in breeding programs to develop grain mold-resistant hybrid lines.

Characterization of subunits encoded by Sn RK1 and dissection of combinations among these subunits in sorghum(Sorghum bicolor L.)

Sucrose nonfermenting-related protein kinase 1(SnRK1)is one of the critical serine/threonine protein kinases.It commonly mediates plant growth and development,cross-talks with metabolism processes and physiological responses to biotic or abiotic stresses.It plays a key role in distributing carbohydrates and sugar signal transporting.In the present study,eight SnRK1 coding genes were identified in sorghum(Sorghum bicolor L.)via sequences alignment,with three forαsubunits(SnRK1α1 to SnRK1α3),three forβ(SnRK1β1 to SnRK1β3),and one for bothγ(SnRK1γ)andβγ(SnRK1βγ).These eight corresponding genes located on five chromosomes(Chr)of Chr1–3,Chr7,and Chr9 and presented collinearities to SnRK1s from maize and rice,exhibiting highly conserved domains within the same subunits from the three kinds of cereals.Expression results via qRT-PCR showed that different coding genes of SnRK1s in sorghum possessed similar expression patterns except for SnRK1α3 with a low expression level in grains and SnRK1β2 with a relatively high expression level in inflorescences.Results of subcellular localization in sorghum leaf protoplast showed that SnRK1α1/α2/α3/γmainly located on organelles,while the rest four of SnRK1β1/β2/β3/βγlocated on both membranes and some organelles.Besides,three combinations were discovered among eight SnRK1 subunits in sorghum through yeast two hybrid,includingα1-β2-βγ,α2-β3-γ,andα3-β3-γ.These results provide informative references for the following functional dissection of SnRK1 subunits in sorghum.

Phenotypical and gene co-expression network analyses of seed shattering in divergent sorghum(Sorghum spp.)

Sorghum[Sorghum bicolor(L.)Moench],a multipurpose C4 crop,is also a model species of the Poaceae family for plant research.During the process of domestication,the modification of seed dispersal mode is considered a key event,as the loss of seed shattering caused a significant increase in yield.In order to understand the seed shattering process in sorghum,we further studied eight previously identified divergent sorghum germplasm with different shattering degrees.We described their phenotypes in great detail,analyzed the histology of abscission zone,and conducted a gene co-expression analysis.We observed that the abscission layer of the most strong-shattering varieties began to differentiate before the 5-10 cm panicles development stage and was completely formed at flag leaf unfolding.The protective cells on the pedicels were also fully lignified by flowering.Through the weighted gene correlation network analysis(WGCNA),we mined for candidate genes involved in the abscission process at the heading stage.We found that these genes were mainly associated with such biological processes as hormone signal transmission(SORBI_3003G361300,SORBI_3006G216500,SORBI_3009G027800,SORBI_3007G077200),cell wall modification and degradation(SORBI_3002G205500,SORBI_3004G013800,SORBI_3010G022400,SORBI_3003G251800,SORBI_3003G254700,SORBI_3003G410800,SORBI_3009G162700,SORBI_3001G406700,SORBI_3004G042700,SORBI_3004G244600,SORBI_3001G099100),and lignin synthesis(SORBI_3004G220700,SORBI_3004G062500,SORBI_3010G214900,SORBI_3009G181800).Our study has provided candidate genes required for shedding for further study.We believe that function characterization of these genes may provide insight into our understanding of seed shattering process.

Development of sorghum mutants with improved in vitro protein digestibility by CRISPR/Cas9 editing of kafirin genes

Sorghum(Sorghum bicolor(L.) Moench) is a major world crop that is a reliable source of fodder and food grain in arid regions. However, unlike other cereals, sorghum grain has low nutritional value, owing mainly to the resistance of its storage proteins(kafirins) to protease digestion. Changing the composition of kafirins or their primary structure may address this problem. To induce mutations in kafirin-encoding genes that were expected to disturb their accumulation in endosperm cells, we used a genome-editing approach. By Agrobacterium-mediated genetic transformation of immature embryos of cv. Avans, we obtained 14 transgenic plants with genetic constructs for site-directed mutagenesis of the k1C5 and g KAF1 genes encoding 22 k Da a-and 28 kDa γ-kafirins, respectively. Sequencing of 5 regenerants obtained by using k1C5-addressing vector revealed two plants with mutations. T_1 progeny of these mutants had higher in vitro digestibility of endosperm proteins(86%–92%), in comparison with the donor Avans(63%–67%). The kernels of these plants had a thick vitreous endosperm. A mutant with increased in vitro protein digestibility and vitreous endosperm, carrying a mutation in the target sequence, was also obtained by use of the gKAF1-addressing vector. Thus, using genome editing technology, we have obtained mutants with improved kafirin digestibility that can be used in sorghum breeding.

Genotypic Divergence, Photosynthetic Efficiency, Sodium Extrusion, and Osmoprotectant Regulation Conferred Salt Tolerance in Sorghum

Salt stress is one of the major limitations to modern agriculture that negatively influences plant growth and productivity.Salt tolerant cultivar can provide excellent solution to enhance stress tolerance with plantfitness to unfavorable environments.Therefore,this study was aimed to screen salt tolerant sorghum genotypes through evaluating of different morphological,biochemical,and physiological attributes in response to salinity stress.In this study,we have been evaluated total six sorghum genotypes including Hybrid sorgo,Debgiri,BD-703,BD-706,BD-707,and BD-725 under salt stress(12 dS m^(-1) NaCl).The response variables included length and weight of root and shoot,root:shoot ratio(RSR),photosynthesis(A),transpiration rate(E),elemental concen-trations(K^(+),Na^(+) and K^(+)/Na^(+)),photochemical efficiency of photosystem II(F_(v)/F_(m)),water use efficiency(WUE)and pigment content(chlorophyll a,and b).The results revealed that saline environment significantly reduced all response variables under study of sorghum genotypes,however,Hybrid sorgo remained unmatched by recording the maximum root and shoot traits.The same genotype recorded higher photosynthetic efficiency which was attributed to Na^(+) extrusion,K^(+) uptake and higher K^(+)/Na^(+) ratio(1.8 at stress),while these mechanisms were not fully active in rest of genotypes.Moreover,this study also implies the involvement of proline in imparting tolerance against saline environment in Hybrid sorgo genotype.Overall,BD-703 remained the most salt sensitive genotype as evident from the minimum morphological growth traits and the least biosynthesis of osmoprotectants.Thesefindings open new research avenues for salt stress alleviation by identifying elite salt-to-lerant genotypes of sorghum for breeding programs.

Textural and functional analysis of sorghum flour cookies as ice cream inclusions

Flour serves as one of the primary ingredients of cookies,which affects dough properties,physical changes during baking,and post-baking cookie properties.Two gluten-free cookie formulations were developed with the goal of use as inclusions in frozen desserts.Blonde and chocolate cookies were made with sorghum flour or all-purpose wheat flour and then evaluated for physical and chemical properties.To determine functionality in a frozen state,texture analysis was conducted on cookies at−30℃,−17°C,and 20℃,replicating various ice cream storage temperatures.To simulate the process effect of incorporating the product into a frozen dessert,cookies were crumbled mechanically,and the crumbles were separated based on size.When evaluating cookies,no significant differences(P<0.05)were observed in width(W),thickness(T),spread,and W/T ratio for flour source within formula.Blonde cookies had lower moisture contents than chocolate cookies;further,blonde cookies made from sorghum flour had less moisture than those made with wheat flour.As the cookie temperature decreased from 20℃to−17℃,cookie hardness increased,with flour type having no effect.Within formula,cookies had similar instrumental color parameters.However,blonde cookies made from sorghum flour produced more smaller-sized pieces than those made from wheat flour.The results of this study demonstrate that sorghum flour cookies have desirable properties for use as inclusions in ice cream and other frozen desserts.

Effect of ultrasound and microwave pretreatment on sprouting,GABA,bioactive compounds,and other physicochemical properties of sorghum

Aim of this study is to see how ultrasound(US)and microwave(MW)pretreatments affectγ-aminobutyric acid(GABA)and physicochemical parameters of sorghum sprouts.Before sprouting,the sorghum was treated with the US at different time intervals(10,15,20 min)and MW at various power levels(10%,30%,50%).Sample treated by the US for 15 min showed the highest sprouting percentage of 97.33%.Both treatments induced stress in grain resulting in GABA accumulation substantially from the control where US for 15 min and MW at 10%power level had the highest of 87.14 and 66.97μg/g,respectively.US treatment for 20 min showed the highest total phenolic content(TPC)of 21.26 mg GAE/100 g,while on 10 min of treatment,it showed the highest antioxidant activity of 84.53%DPPH inhibition.The water absorption capacity and oil absorption capacity were the highest of 0.86 g/g and 0.98 g/g in the MW-treated sample at 10%output power respectively.In conclusion,the ultrasound treatment successfully accelerated the sprouting rate and GABA content while retaining total phenolic content,making it beneficial for developing functional foods.

Farmers’ Perception of Phenotypic Variation of Different Types of Sorghum Cultivated in Burkina Faso

Sorghum bicolor is a multi-purpose species adapted to many agroecological zones of Burkina Faso. In the local farming system, different types of sorghum are cultivated together. Such farming conditions could increase gene flow between the different types of sorghum and contribute to the evolution of their main morphological characteristics. Understanding the effect of the farming system on the characteristics of different types of sorghum could contribute to building a strategy for the management of its genetic diversity. A survey and accessions collection was carried out in ten villages selected in two agroclimatic zones of Burkina Faso. A total of 133 accessions were collected and thirty local names were recorded. The results revealed a significant variability within sorghum characteristics based on farmers’ descriptions. Four types of sorghum were identified by farmers based on their uses. These are sweet grain sorghum, grain sorghum, sweet sorghum and dyer sorghum. Most of farmers (54.6%) practised intercropping, and 28.86% of them intercropped several types of sorghum in the same or nearby fields. A high coincidence of the flowering period of the types of sorghum was observed by farmers in both agroclimatic zones. The results also showed that most of the farmers (55.7%) noted changes in the morphological characteristics of different types of sorghum. These variations included the reduction in potential yields and changes in grain taste and colour within the same type. Understanding these variations could help conserve and sustain sorghum genetic resources in Burkina Faso.

Study on Distribution Characteristics and Occurrence Form of Soil Fluorine in Sorghum Base of Renhuai City

In order to find out the effects of soil fluorine on ecological environment and crop safety in the sorghum cultivation base of Renhuai City, Guizhou Province, the content and the occurrence forms of soil fluorine and its influencing factors of Maoba Town were investigated and studied. The results showed that the total fluorine content in the soil of the sorghum base ranged from 668.60 to 2 596.80 mg/kg, with an average of 1 483.25 mg/kg, which was 3.10 and 1.85 times of the national soil background value and the average value of the soil in endemic areas, respectively. The spatial distribution of fluorine in the soil of the study area was uneven, and the fluorine content was in the order of Anliang Village>Yangliu Village>Houba Village>Xiongfeng Village. The soil fluorine contents of various forms varied greatly, and the distribution law was as follows: residual state>water soluble state>organically bound state>exchangeable state>Fe/Mn-F state. The residual fluorine content was the highest, accounting for more than 99% of total fluorine content, while the sum of other four forms was less than 1%, with their respective proportions ranging from 0.10% to 0.30%. The content and proportion of available fluorine in water-soluble and exchangeable states were relatively low, which had limited influence on the surrounding water environment and crop safety. The physicochemical properties of soil, such as pH, organic matter, cation exchange capacity and clay particles had a certain influence on the occurrence forms of soil fluorine, thus changing the availability and migration of soil fluorine, which might endanger the ecological environment safety, food safety and human health.

Farmer Participatory Evaluation of Sorghum Hybrid in Niger

Participatory varietal selection (PVS) with farmers and Seed Companies was conducted at Maradi research station (07°05'E/13°48'N) and in farmer field to evaluate and select sorghum hybrid varieties for high yield and other important agronomic traits. The experimental design was a randomized complete block with three replications where flowering (days), plant height (cm) and yield (kg) were collected. The analysis of variance showed highly significance among treatments of all traits measured Environment and Genotype by Environment interactions also contributed significantly to the performance of yield components. The highest average grain yield was recorded from hybrids P9511A x ST9007-5-2-1 (4289 kg/ha), NE223A x 90SN1 (3666 kg/ha), NE223A x Sepon 82 (3533 kg/ha) and NE223A x P9405 (3519 kg/ha) across locations. Farmers’ preferences were the panicle size, good seed set, earliness, and seed color. Hence, in a variety selection farmer’s preferences focus more on prioritized yield-related trait. The best varieties ranked by traits of interest were P9511A x ST9007-5-2-1, NE223A x 90SN1, NE223A x P9405 and P9511A x SEPON 82 that performed well under their circumstances. The results showed that farmers’ preferred varieties match with researchers. Therefore, based on objectively measured traits, farmers’ preferences and the agro ecologies of the site, varieties NE223A x 90SN1 and P9511A x ST9007-5-2-1 were found promising for production.

Using Sorghum Stalk as a Partial Replacement of Lime in the Stabilization of Red Clay Soil for Road Sub-Grade Construction

This research aimed at testing the viability of using Sorghum Stalk Ash (SSA) as a partial replacement of lime in the stabilization of red clay soils for road subgrade construction. Red clay soils have been identified as highly expansive soils, which are affected by both climatic conditions and loading patterns. The consideration of both traffic loading patterns and climatic effects on these soils has been taken into account. A penetration test of 2.5 mm has been used on both pure red soils and stabilized soils at 10% and 15% partial replacement of lime with SSA and showed an improvement in the CBR of stabilized red clay soils up to 11.6%. Again, the PI of stabilized soils at 15% partial replacement of lime reduced up to 11.2%. The results obtained on both CBR and PI of these red clay soils are within the recommended values for the effective subgrade required for laying both permanent and flexible pavements. As a result, a recommendation of making use of SSA to lower the quantities of lime and its costs used in the stabilization of highly expansive soils have been tested through this research. However, further research on a more percentage partial replacement of lime to improve the PI of these soils to below 10% while keeping the CBR levels within the road construction regulations is welcomed.

The Research on Identification of Resistance to Sorghum Aphid [Melanaphis Sacchari(Zehntner)] Employing Indoor Artificial Infestation Technique

[ Objective] The paper was to establish a quick and effective indoor identification method of sorghum resistance to aphid uninfluenced by seasons. [ Method] Based on the indoor reproduction technique of aphids, the sorghum varieties with different resistant performances against aphids in fields were conducted inoculation test in the laboratory according to different seedling culture media, different survey periods of aphid quantity, different leaf ages for inoculation, different inoculation quantity of aphids and different aphid sizes. Three hundred sorghum materials were identified in both laboratory and field. [ Result ] The number of aphids per seedling on the fifth day after inoculation gave the best score of plant resistance to sorghum aphid by using the loam as the seedling culture media, and inoculating three different sizes of aphids in seedlings at two-leaf stage. Thus, the indoor identification technique of resistance to sorghum aphids was as follows ： （ 1 ） sorghum seeds were sown in loam at room temperature of 22 - 26 ℃ and air humidity of 55% - 75% ; （2） three aphids with different sizes were inoculated in scedIings at two-leaf stage; （3） the number of aphids per seeding were surveyed on the fifth day after inoculation; （4） plant resistance to sorghum aphid was evalu- ated according to number of aphids per seedling on the fifth day after inoculation. The resistant grade of sorghum variety was evaluated according to distribution of aphid quantity per seedling in a 100-seedlings population. The resistance materials identified by indoor method at seedling stage had consistent performance with fidd identification. [ Conclusion] The method could be used for resistance identification of sorghum varieties and hybrids, and accurate identification and selectlon of individual resistance of hybrid offspring, which could improve selection efficiency of individual resistant plant against aphids in hybrid offspring and identification accuracy of individual resistant plant among molecular marker population.

高粱(Sorghum bicolor(L.)Moench)种质资源研究进展

高粱(Sorghum bicolor(L.)Moench)是世界上主要的旱粮作物,也是全球5亿多人口的主要粮食。文章对高粱的起源与分类、高粱种质资源收集、保存和利用以及遗传多样性研究与核心种质的构建等方面的研究进行了综述,最后对我国高粱种质资源的研究方向进行了展望。