Daily rhythms in the sorghum shootfly, Atherigona soccata: oviposition, egg-hatch and adult eclosion

ABSTRACT. Daily rhythms controlling oviposition, egg-hatching and adult eclosion in the sorghum shootfly, Atherigona soccata Rondani, were investigated. Eggs were laid only during the photophase of a LD 12:12 cycle, in two peaks. Under continuous light, this oviposition was considerably attenuated but not made immediately arrhythmic. Egg-hatching and adult eclosion both commenced just before dawn. Some feature of the scotophase during or immediately after black-head formation apparently acts as a signal for hatching. Eclosion was controlled by light but its timing in the field was modified by temperature. The last 2–3 days of the pupal period constituted the most sensitive stage, and light signals received during this period determined the time of eclosion. Ecological advantages of these rhythms to the shootfly are discussed.     

Physico‐chemical mechanisms of resistance to shoot fly,Atherigona soccata in sorghum,Sorghum bicolor

Sorghum shoot fly, Atherigona soccata is an important pest of sorghum, and host plant resistance is one of the important components for minimizing the losses due to this pest. Therefore, we evaluated a diverse array of sorghum genotypes to identify physico‐chemical characteristics conferring resistance to A. soccata. Susceptibility to shoot fly was associated with high amounts of soluble sugars, fats, leaf surface wetness and seedling vigour; while leaf glossiness, plumule and leaf sheath pigmentation, trichome density and high tannin, Mg and Zn showed resistance to shoot fly. Stepwise regression indicated that Mg, Zn, soluble sugars, tannins, fats, leaf glossiness, leaf sheath and plumule pigmentation and trichome density explained 99.8% of the variation in shoot fly damage. Path coefficient analysis suggested that leaf glossiness, trichome density, Mg and fat content and plant plumule pigmentation can be used as markers traits to select for shoot fly resistance in sorghum.     

密植条件下种植方式对夏玉米群体根冠特性及产量的影响

选用平展大穗型品种鲁单981(Ludan981,LD981)和紧凑中穗型品种鲁单818(Ludan818,LD818),在两种种植密度(60000和90000株/hm2)和两种种植方式(单株和双株)下,研究了密植及种植方式对夏玉米冠层和根系结构与功能以及子粒产量等的影响.研究发现,随种植密度增加,冠层垂直分布呈现干重比例权重上移的趋势,根系则呈现下移的趋势.密植条件下,LD981冠层对生长空间更为敏感,其根系对生长空间的竞争强于冠层,其群体产量限制因素是子粒库容;LD818根系对生长空间更为敏感,冠层对生长空间的竞争强于根系,其群体产量限制因素是单位面积穗数.60000株/hm2下,LD981的群体结构质量和功能较优,双株种植可缓解其冠层竞争,根、冠协调,表现增产;在90000株/hm2下,LD818的群体结构质量和功能较优,双株种植可缓解其根系竞争,部分改善冠层群体结构质量和功能,根、冠协调,表现增产.     

高油、高淀粉玉米吸硫特性及施硫对其产量、品质的影响

研究了高油、高淀粉玉米硫素的吸收分配及施硫对籽粒产量、品质的作用。结果表明：在11250kg/hm^2的产量水平下,开花前硫素吸收量占总吸收量的百分比平均为57.53%,花后对硫的吸收较强;高油1号、长单26、掖单13每公顷吸硫量分别为：32.46kg、34.94kg,34.20kg。施硫能增加穗粒数和粒重（高油玉米粒重增加不显著）,并显著提高其产量,施硫22.5kg/hm^2（S1）能使籽粒含油率和蛋白质含量分别比对照提高9.05%和6.88%,蛋白质中清蛋白、球蛋白和谷蛋白含量提高,品质改善;施硫量增至90kg/hm^2(S2)时,籽粒含油率和蛋白质含量仍有提高,但蛋白质中醇溶蛋白含量增加,蛋白质品质降低。     

Interaction among planting dates,transgenic maize,seed treatment,corn rootworm damage and grain yield

A study was conducted from 2006 to 2008 at South Charleston and Wooster, Ohio, USA, to evaluate the potential use of planting dates in combination with Bacillus thuringiensis transgenic maize and insecticidal seed treatments to manage the root feeding of western corn rootworm (Diabrotica virgifera virgifera, Coleoptera: Chrysomelidae). Three planting dates (early, middle and late), targeting late April/early, mid‐May and early June, respectively, were used. We planted six hybrid treatments consisting of two seed‐treated hybrids with seed treatment, two transgenic hybrids and two untreated hybrids, each set represented by one short and one full season maturity hybrid. When root injury was high, significant lodging and stunted growth were observed on untreated maize and declined when planting was delayed. Root injury by rootworm larval feeding was significantly reduced by later planting maize, that is, early June. The use of transgenic maize and seed treatment also significantly reduced root injury by rootworm larvae. The influence of planting date on grain yield was inconsistent from year to year. Grain yields from short season hybrids were comparable to full season hybrids especially on later plantings. These results showed that the use of a seed treatment and transgenic maize might be beneficial only when rootworm population is high and planting is early.     

Leaf surface wetness in sorghum and resistance to shoot fly, Atherigona soccata: role of soil and plant water potentials

In experiments with potted plants, the relationships between soil matric potential, plant water potential and production of water droplets (leaf surface wetness) on the folded central whorl leaf of seedlings of sorghum genotypes that are either resistant or susceptible to shoot fly (Atherigona soccata) damage were investigated. Differences in soil matric potentials in the pots affected the plant water status, which in turn had profound effects on the production of water droplets on the central whorl leaf of the sorghum genotype susceptible to shoot fly. There was no consistent variation in the relationship between plant water potential and soil matric potential of resistant and susceptible sorghum genotypes. However, there was very little or practically no water droplets on the central whorl leaf of the resistant genotypes, indicating that the production of water droplets is not solely the result of internal water status of the plant. It is suggested that leaf surface wetness is genetically controlled and that an understanding of the mechanism by which water is transferred to the leaf surface will enhance breeding for resistance to shoot fly.     

垄作栽培对高产田夏玉米光合特性及产量的影响

试验于2006-2007年在河南省浚县农业科学研究所试验田进行,以传统平作为对照,研究了垄作栽培对夏玉米光合特性和产量的影响.结果表明,垄作提高了夏玉米光合速率Pn、叶片蒸腾速率Tr和气孔导度Gs,且其日变化均呈单峰曲线,12:00达到最大值,而细胞间隙二氧化碳浓度Gi有所降低,其日变化与Pn相反,呈倒抛物线型.垄作栽培夏玉米的最大光化学效率Fv/Fm和实际光化学效率φPSⅡ均有所增加.与平作相比,垄作后期叶面积衰减较慢,籽粒蜡熟期和成熟期垄作比平作叶面积指数分别高6.4％和3.7％,减少了漏光损失,垄作栽培延长了叶片功能期,促进光合产物的积累及向籽粒的转移,有利于后期玉米籽粒充实,千粒重显著高于平作,产量提高9.6％.     

The effect of abscisic acid on cell growth, cell division and DNA synthesis in the maize root meristem

Cis -abscisic acid (ABA), when applied to maize ( Zea mays L. cv. LG 11) roots, decreases the rates of cell growth and cell division in the meristem. It also decreases the rate at which nuclei become labelled with [³H]-thymidine and enter mitosis. Removing the root cap accelerates the entry of nuclei into the DNA synthetic phase of the mitotic cycle and enhances the rate of cell proliferation in the quescent centre. ABA diminishes these effects, but does not suppress them. Thus, ABA cannot wholely substitute for the presence of a cap. One of the primary effects of applied ABA is to retard cell enlargement which may in turn affect the rate of cell division; natural endogenous ABA may act similarly. ABA might in this way assist in maintaining the quiescent centre in intact roots, but cannot be the sole agent involved.     

Morphological factors of the central whorl leaf associated with leaf surface wetness and resistance in sorghum to shoot fly,Atherigona soccata*

Earlier studies showed that leaf surface water on the central whorl leaf of sorghum seedlings is associated with resistance to shoot fly. In this study, the results of an experiment to determine if leaf surface wetness (LSW) originates from atmospheric condensation or from the plant are described. Morphological structures: trichomes, stomata, leaf cuticle and quantity of surface wax of the central whorl leaf were also examined for their role in LSW production. The results suggest that LSW of the central whorl leaf originates from the plant and is not due to condensation of atmospheric moisture. The presence of trichomes was indirectly associated with LSW and resistance to shoot fly but stomatal density was not associated with LSW production. The amount of wax extracted per 100 mg of fresh weight varied significantly between genotypes and seedling age. It was more in susceptible than in resistant genotypes; however, cuticular thickness was not associated with resistance. It is suggested that LSW could be the result of some form of cuticular movement of water to the leaf surface.     

Pattern of sulfate uptake during root elongation in maize: its correlation with productivity

The efficiency of sulfate uptake was evaluated in excised roots of 22 maize genotypes, 12 inbreds and 10 hybrids, in order to study the relationship between the kinetic characteristics of the uptake and the grain productivity. During root elongation, the uptake capacity showed a pulse which appeared when the root reached 1/3 to 1/2 of its final length. The size of the accumulated pool of sulfate was significantly correlated with the productivity. The kinetic parameters of the uptake, Vmax and Km, followed the same trend, showing pulses, whoxe maximum had the same position for Vmax and Km in each genotype. The variability with the genotype of the size and duration of the Vmax pulse was not strictly connected with that of Km. The main correlation between Vmax and Km patterns was the following; inbreds were generally characterized by low Vmax and low Km; hybrids by high Vmax and high Km. As a consequence, in most cases, the benefit of the heterotic stimulation of Vmax was contrasted by the loss of affinity of the transport system or the nutrients.     

Two consensus quantitative trait loci clusters controlling anthesis–silking interval, ear setting and grain yield might be related with drought tolerance in maize

Unravelling the molecular basis of drought tolerance will provide novel opportunities for improving crop yield under water-limited conditions. The present study was conducted to identify quantitative trait loci (QTLs) controlling anthesis–silking interval (ASI), ear setting percentage (ESP) and grain yield (GY). The mapping population included 234 F₂ plants derived from the cross X178 (drought tolerant) × B73 (drought susceptible). The corresponding F_2:3 progenies, along with their parents, were evaluated for the above-mentioned traits under both well-watered and water-stressed field conditions in three different trials carried out in central and southern China. Interval mapping and composite interval mapping identified 45 and 65 QTLs for the investigated traits, respectively. Two QTL clusters influencing ASI and ESP on chromosomes 1 (bin 1.03) and 9 (bins 9.03–9.05) were identified in more than two environments, showing sizeable additive effects and contribution to phenotypic variance; these two QTL clusters influenced GY only in one environment. No significant interaction was detected between the two genomic regions. A comparative analysis of these two QTL clusters with the QTLs controlling maize drought tolerance previously described in three mapping populations confirmed and extended their relevance for marker-assisted breeding to improve maize production under water-limited conditions.     

Resistance in sorghum to the shoot fly, Atherigona soccata: epicuticular wax and wetness of the central whorl leaf of young seedlings

Sorghum genotypes known to be resistant or susceptible to shoot fly, Atherigona soccata Rondani were examined by scanning electron microscopy for differences in epicuticular wax structure and wetness of the central leaf whorl. Two major types of wax structures were observed: shoot fly resistant and moderately resistant genotypes were characterised by a smooth amorphous wax layer and sparse wax crystals while susceptible genotypes possessed a dense meshwork of crystalline epicuticular wax. The density of wax crystals decreased from the third leaf to the seventh leaf stage and was related to both seedling age and leaf position. Water droplets on susceptible genotypes with dense wax crystals showed spreading at the edges indicating a tendency to wet easily. In resistant genotypes with less dense wax crystals the droplets remained intact and did not spread.     

基于分期播种的气候变化对东北地区玉米(Zea mays)生长发育和产量的影响

利用在东北地区中部开展玉米(Zea mays)分期播种试验资料,分析气候变化对玉米出苗速度、生长发育速度、灌浆过程、植株干物质积累和产量的影响,进而分析未来气候变化对东北地区玉米生产的影响及适应性对策.结果表明,气候变化对玉米生长发育和产量的影响十分明显,在水分基本适宜的条件下,东北地区气候变暖导致玉米生长季气温升高、积温增加,使玉米生长发育和灌浆速度加快,生物量增加,从而提高单产.但气候变暖的同时,气候变干会限制热量资源的利用,将缩短玉米灌浆时间,降低灌浆速率,使千粒重下降,从而造成明显减产,而且减产幅度明显大于温度升高的增产幅度.在水分条件基本得到满足的条件下,未来夏半年气候变暖对东北地区玉米生产是有利的,偏晚熟玉米品种比例可以适当扩大,东北玉米带可以向北部和东部扩展,单产和总产都会增加;但如果水分得不到满足,气候的暖干化趋势会使东北地区的中、西部玉米主产区的农业干旱变得更加严重且频繁,造成产量下降和不稳定,给玉米生产带来严重威胁,因而更应加强农业干旱的综合防御工作.     

密度和种植方式对夏玉米酶活性和产量的影响

在豫北灌区的生产条件下,以郑单958和浚单20为试验材料,研究了不同密度和种植方式对夏玉米碳氮关键酶的影响。结果表明:生育后期夏玉米叶片硝酸还原酶(NR)、谷氨酰胺合成酶(GS)和籽粒蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SS)活性均呈先升高后降低的变化趋势,叶片NR和GS活性峰值出现在吐丝期,籽粒SPS和SS活性峰值出现在灌浆后15d。基因型、密度和种植方式对夏玉米生育后期叶片NR、GS和籽粒SPS、SS活性均有显著影响,而3因素间总体上没有显著的互作效应。郑单958生育后期叶片NR、GS和籽粒SPS、SS活性均显著高于浚单20,分别提高5.02%、7.40%、6.25%和4.43%。在6.75—9.00万株hm2的范围内,随着密度的增大,夏玉米生育后期叶片NR、GS和籽粒SPS、SS活性显著降低。与60cm等行距种植方式相比,80cm-40cm宽窄行种植方式下夏玉米生育后期叶片NR、GS和籽粒SPS、SS活性均显著提高,分别提高6.23%、9.25%、6.87%和2.84%。在采用宽窄行种植、密度为8.25万株hm2时,产量最高。     

种植方式和密度对夏玉米光合特征及产量的影响

为探明种植方式和密度对玉米光合特征及产量的影响,以郑单958为材料,在不同种植密度水平(67500株/hm2和82500株/hm2)下,以常规等行距种植方式为对照,设置3种不同缩行宽带种植方式(三行一带、四行一带、五行一带)进行比较研究。结果表明:与对照相比,无论高密度还是中等密度下,各缩行宽带种植方式均使玉米穗位上第1叶茎叶夹角显著减小,其中中三行一带种植方式穗位上两叶叶夹角值均最小;各缩行宽带种植方式光合速率(Pn)均不同程度高于对照,子粒产量显著增加,其中三行一带、四行一带、五行一带种植方式分别比对照增加16.7%、6.1%、10.7%(2011年)和17.2%、12.1%、10.6%(2012年)。所有处理中,三行一带种植方式高密度处理2011年和2012年籽粒产量均最高,因此可推荐为黄淮海夏玉米高产高效种植新方式。     

Observations on longevity and fecundity of the sorghum shoot fly, Atherigona soccata (Diptera; Anthomyiidae)

Longevity and fecundity of the sorghum shoot fly, Atherigona soccata Rond. were mainly affected by the adult food. Lack of mating reduced fecundity and affected the rate of oviposition in the females, but did not affect longevity. The mean number of eggs per mated female was 62.8±0.9. Oviposition began at a mean period of 4.7 days after adult emergence. Mean longevity of females and males was 32.6±0.3 and 25.4±0.4, days, respectively.

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Résumé La longévité et la fécondité de Atherigona soccata dépendent avant tout de la nourriture de l'adulte. L'absence d'accouplement réduit la fécondité et modifie le taux de ponte des femelles, mais ne touche pas leur longévité. Le nombre moyen d'ufs pondus par femelle accouplée est 62,8±0,9 (extrêmes 10–167). La ponte commence en moyenne 4–7 jours après l'émergence des adultes (extrêmes 2 et 14 jours). La longévité moyenne des femelles et des mâles est respectivement de 32,6±0,3 jours et 25,4±0,4 jours.

     

Effect of salicylic acid on nitrite reductase and glutamate dehydrogenase activities in maize roots

The effects of 0.01 to 5 m M salicyclic acid on the increase in nitrite reductase or glutamate dehydrogenase activities in maize roots by nitrate or ammonium respectively, were examined. Nitrite reductase activity was inhibited by the highest concentration of the acid. The activity of NADH-glutamate dehydrogenase was stimulated slightly (but consistently) by the lowest concentration and was inhibited by higher concentrations. Total protein content was also inhibited at high concentrations. When the crude enzyme extract was stored at 25°C in light, the glutamate dehydrogenase activity in the control decreased after 4 h of incubation. Low concentrations of the acid had no effect on this decrease but higher concentration accelerated the process. The divalent cations Caz²⁺, Mn²⁺, Mg²⁺ and Zn²⁺ protected against loss of enzyme activity during storage, both in the absence and presence of the acid. The inhibitory effect of 5 m M salicylic acid on glutamate dehydrogenase activity is apparent due to interference with the activity of the enzyme rather than with its synthesis.     

Effects of water stress on growth, osmotic potential and abscisic acid content of maize roots

Under water stress conditions, induced by mannitol solutions (0 to 0.66 M ) applied to the apical 12 mm of intact roots of Zea mays L. (cv. LG 11), a growth inhibition, a decrease in the osmotic potential of the cell sap and a significant accumulation of abscisic acid (ABA) were observed. When the roots were placed in a humid atmosphere after the stress, the growth rate increased again, even if elongation had been totally inhibited. Under a stress corresponding to an osmotic potential of -1.09 MPa in the solution, growth was totally inhibited, which means that the root cell turgor pressure was reduced to the yield threshold. These conditions led to the largest accumulation of ABA. The effect of water stress on the level of ABA was studied for three parts of the root. The greatest increase in ABA (about 10 fold) was obtained in the growth zone and this increase was apparently independent of the hydrolysis of the conjugated form. With a mannitol treatment of 1 h equivalent to a stress level of -1.39 MPa, a 4-fold increase in ABA efflux into the medium was obtained. These results suggest that there are interactions between water stress, root growth, osmotic potential and the ABA level. The growth under conditions of stress and the role of endogenous ABA in the control of plant metabolism, specially in the growth zone, are discussed.     

沟垄全覆盖种植方式对旱地玉米生长及水分利用效率的影响

2008-2010年在渭北旱塬区,以沟不覆盖为对照(CK),研究垄上覆地膜沟内分别覆普通地膜(PP)、生物降解膜(PB)、玉米秸秆(PS)和液体地膜(PL)4种沟垄全覆盖种植模式对土壤水温、玉米生长、产量及水分利用效率的影响.结果表明,在玉米生长前期,PP、PB和PS处理可明显提高0-200 cm土壤蓄水量;生育中期,PS处理蓄水保墒效果最为显著;生育后期,各沟垄全覆盖处理与对照的土壤蓄水量无显著差异;整个生育期PL处理与CK的土壤蓄水量差异不显著.PP和PB处理3a玉米生育期5-25 cm平均土壤温度分别较CK增高1.6℃和1.3℃,PS处理降低1.9℃,而PL处理与CK无显著差异.PP和PB的增温保水效应使玉米株高、叶面积及地上生物量均高于CK;PS处理的降温效应促进玉米中后期生长,其株高、叶面积及地上生物量均高于CK;PL处理对玉米各生长指标影响不显著.与CK相比,PP、PB和PS处理3a平均的籽粒产量分别提高13.0％、13.8％和15.0％,水分利用效率分别提高9.8％、10.2％和11.6％.可见,垄覆地膜沟覆地膜、生物降解膜或秸秆的沟垄全覆盖种植可明显改善土壤的水温状况,促进玉米生长,从而显著提高作物产量和水分利用效率,对渭北旱塬区春玉米丰产栽培具有重要指导意义.     

玉米株型和幅宽对套作大豆初花期形态建成及产量的影响

在“麦/玉/豆”套作模式下研究了不同幅宽和玉米株型对大豆生长前期形态建成和产量的影响.结果表明：不同株型玉米下大豆生长带的温度、湿度和透光率是导致大豆茎叶形态和组织解剖结构出现差异的直接原因.较大幅宽和紧凑型玉米下大豆的植株较矮,主茎较粗、干物质积累量较大,叶面积指数和比叶质量较高,产量较高;而较小幅宽和松散型玉米下大豆的茎叶生长不良,株高增长过快,主茎柔弱,容易倒伏,产量较低.在1.17 m/0.83 m(大豆/玉米)幅宽下对不同株型玉米影响下的大豆初花期茎、叶组织切片观察发现,随着荫蔽程度的加重,大豆的叶片变薄,表皮细胞体积变大,角质层变薄,栅栏组织和海绵组织分化不明显,细胞间隙增大;茎的表皮和次生木质部也变薄,薄壁细胞排列疏松,导管分化较迟,韧皮纤维不发达.套作模式下保证全年高产、高效的田间最优配置为：与紧凑型玉米套作,大豆幅宽1.17 m,玉米幅宽0.83 m.