Influence of take-all epidemics on winter wheat yield formation and yield loss

ABSTRACT The effects of take-all epidemics on winter wheat yield formation were determined, and disease-yield relationships were established to assess the agronomic efficacy and economic benefits of control methods. Epidemics were generated in naturally infested fields by varying cropping season, crop order in the rotation, and experimental fungicide seed treatment. Disease incidence and severity were assessed from tillering to flowering. Yield components were measured at harvest. Models simulating the formation of the yield components in the absence of limiting factors were used to estimate the losses caused by take-all. Losses were predicted by the disease level at a specific time or the area under the disease progress curve, reflecting accumulation during a specific period. Losses of grain number per square meter and 1,000-grain weight were linked to cumulative disease incidence between the beginning of stem elongation and flowering, and disease incidence at midstem elongation, respectively. Yield losses were accounted for by both cumulative disease incidence between sowing and flowering, and disease incidence at midstem elongation. Results confirm the importance of nitrogen fertilization in reducing the impact of take-all on wheat.     

Effects of sharp eyespot (Rhizoctonia cerealis) on yield and grain quality of winter wheat

Sharp eyespot caused by Rhizoctonia cerealis was assessed in four winter wheat crops surveyed at four locations in north-central Poland in 2006?C2009. At the four locations symptoms developed on 41.9?C67.7?% of shoots of all plants (average of 4?years) and on 49?C73.5?% of shoots of diseased plants (average of 4?years). Slight (category 1) disease was most frequent, occurring on 24.4?C41.3?% of shoots (range 14.8?C51.3?%); moderate (category 2) disease was less frequent, occurring on 16.9?C25.5?% of shoots (range 8.9?C32.4?%); severe (category 3) disease was least frequent, occurring on 3.2?C7.1?% (range 0?C22.0?%) of shoots. Sharp eyespot affected wheat growth and yield, and grain quality. Disease, especially in the severe category, was associated with significant decreases in plant and ear dry weights, number of grains per ear, grain dry weight per ear and thousand-grain weight, and with increases in grain protein and wet gluten contents, Hagberg falling number and sedimentation value. There was an association between occurrence of sharp eyespot in stems and colonization of grain by fungi. Alternaria alternata and E. nigrum were the most common species.     

Influence of crop management on take-all development and disease cycles on winter wheat

ABSTRACT Wheat was assessed at four crop growth stages for take-all (Gaeumannomyces graminis var. tritici) in a series of field trials that studied the effects of five wheat management practices: sowing date, plant density, nitrogen fertilizer dose and form, and removal/burial of cereal straw. An equation expressing disease level as a function of degree days was fitted to the observed disease levels. This equation was based on take-all epidemiology and depended on two parameters reflecting the importance of the primary and secondary infection cycles, respectively. Early sowing always increased disease frequency via primary infection cycle; its influence on the secondary cycle was variable. Primary infection and earliness of disease onset were increased by high density; however, at mid-season take-all was positively correlated to the root number per plant, which was itself negatively correlated to plant density. At late stages of development, neither plant density nor root number per plant had any influence on disease. A high nitrogen dose increased both take-all on seminal roots and severity of primary infection cycle but decreased take-all on nodal roots and secondary infection cycle. Ammonium (versus ammonium nitrate) fertilizer always decreased disease levels and infection cycles, whereas straw treatment (burial versus removal of straw from the previous cereal crop) had no influence.     

播期和密度对普冰151小麦籽粒产量与品质的影响

为确定关中地区小麦适宜播期和密度,以普冰151为试验材料,于2014年10月—2015年6月设置10月3日、10月8日、10月13日3个播期和基本苗135、195、255、315万·hm~(-2)4个密度,研究了播期和密度对普冰151产量及品质的影响。结果表明,随着播期的推迟,普冰151的籽粒产量降低,通过增加密度可以提高小麦成穗数,达到增加产量的目的。从播期和密度互作对产量的影响来看,普冰151的适宜播期为10月3日至10月8日,播量随着播期的推迟而增加,基本苗由10月3日的195万·hm~(-2)增加到10月8日的255万·hm~(-2)。随着播期的推迟,蛋白质含量和湿面筋含量呈下降趋势,面团稳定时间呈上升趋势;当密度为255万·hm~(-2)时,蛋白质含量、湿面筋含量和面团稳定时间最大,分别为14.25%、30.72%和10.22 min。因此,可根据实际需要,确定最适宜的播期和密度,使产量和品质协调统一。     

Effect of Heterodera cajani on biomass and grain yield of pigeon pea on vertisol in pot and field experiments

Glasshouse and field trials were conducted to determine the effects of the cyst nematode, Heterodera cajani on biomass and grain yield of pigeon pea, Cajanus cajan. Shoot length, fresh and dry shoot masses, leaf area and pod yields of pigeon pea were significantly reduced by H. cajani. In glasshouse pot experiments, an initial density of 1.0 juveniles per cm³ soil caused 14 to 24% reduction in plant height, root and shoot mass and leaf area. Application of carbofuran 3G (1·5, 3·0 and 6·0 kg a.i./ha) in H. autoclaved soil in pots did not improve growth of pigeon pea; however, its application (6 kg a.i./ha) in H. cajani -infested fields reduced the nematode density ( P < 0·05) and improved plant growth and yield. The densities of eggs and juveniles of H. cajani were 72 and 48% lower in the carbofuran-treated plots than in the control plots 35 and 52 days, respectively, after sowing. No such differences were observed at 70 days after sowing. The tolerance limit for pod yield in field experiments was 2·6 eggs and juveniles of H. cajani per cm³ soil at sowing time. Grain yield was 20 to 25% higher in the carbofuran-treated plots than in the control plots. Application of carbofuran protected the roots from nematode damage during the early stages of plant growth and resulted in good plant growth and yield.     

灌浆天数对北方白菜型冬油菜产量和品质的影响

为了研究北方白菜型冬油菜在灌浆成熟过程中产量和品质性状的特征特性变化,以白菜型冬油菜陇油12号和09鉴8为材料,分析冬油菜在终花后10、20、30、40、45 d的植株、角果、籽粒形态和干鲜重,产量和品质性状的变化。结果表明,随着籽粒灌浆成熟,植株和角果颜色呈墨绿—青绿—黄绿—蜡黄—肤白色变化。角果中籽粒大小呈小—大—小变化,种子颜色呈绿色—褐绿相间—褐色—紫色—黑色变化。植株、角果、籽粒鲜重呈先增加后降低的单峰变化曲线,基本呈抛物线状,且分别在终花后20、30、40 d鲜重达到最大,而植株、角果、籽粒干重呈先增加后保持不变的变化趋势。同时千粒重、单株产量、经济系数也呈先增加后保持不变的S型增长曲线,且在终花后30 d达到最大,之后保持不变。相关分析表明,灌浆时间长短与籽粒鲜重、千粒重、经济系数呈极显著的正相关关系,相关系数分别为0.991、0.962、0.968(P0.01);与单株产量、含油率呈显著的正相关关系,相关系数分别为0.947、0.940(P0.05);与蛋白质呈显著的负相关关系,相关系数为-0.886(P0.05)。通过主成分分析方法打分,各处理的综合得分排名为40 d45 d30 d20 d10 d,因此,籽粒灌浆天数对白菜型冬油菜的产量和品质影响明显。综合评价得出,蜡黄期(约终花后40 d)产量和品质等性状达到最佳,是收获的最适宜时期。     

The effects of postplanting environment on the incidence of soilborne viral diseases in winter cereals

ABSTRACT Soilborne wheat mosaic virus (SBWMV) and Wheat spindle streak mosaic virus (WSSMV) are putatively transmitted to small grains by the obligate parasite Polymyxa graminis, but little is known about environmental requirements for transmission and the resulting disease incidence. We planted susceptible wheat and triticale cultivars in field nurseries on different autumn dates in 3 years and observed the incidence of symptomatic plants in each following spring. Autumn postplanting environment explained most of the variation in disease caused by both viruses. Little apparent transmission, based on eventual symptom development, of either virus occurred after the average soil temperature dropped below 7 degrees C for the remainder of the winter. To forecast disease, we tested an SBWMV transmission model in the field, based on laboratory results, that predicts opportunities for transmission based on soil temperature and soil moisture being simultaneously conducive. This model was predictive of soilborne wheat mosaic in 2 of 3 years. Zoospores of P. graminis have optimal activity at temperatures similar to those in the SBWMV transmission model. Furthermore, the matric potential threshold (as it relates to waterfilled pore sizes) in the SBWMV transmission model fits well with P. graminis as vector given the size restrictions of P. graminis zoospores. Conditions optimal for SBWMV transmission in the laboratory were not conducive for WSSMV transmission in the laboratory or for wheat spindle streak mosaic development in the field. This differential response to environment after emergence, as indicated by disease symptoms, may be due to virus-specific environmental conditions required to establish systemic infection via the same vector. Alternatively, the differential response may have been due to the involvement of a different vector in our WSSMV nursery than in our SBWMV nursery. Our results suggest that, as a control tactic for SBWMV or WSSMV, earliness or lateness of planting is less important in determining virus transmission and disease than the specific postplanting environment. Improved models based on the postplanting environment might predict virus-induced losses of yield potential, and in some cases, growers might avoid purchase of spring inputs such as pesticides and fertilizer for fields with greatly reduced yield potential.     

耕种方式对冬小麦籽粒灌浆特性及产量的影

通过大田定位试验,研究了免耕条播、深松条播、旋耕条播、机械撒播等4种耕种方式下冬小麦强势粒灌浆特性,用Logistic方程拟合籽粒灌浆进程,对籽粒灌浆参数进行了分析.试验结果表明,方程拟合决定系数均在0.9942以上,Logistic方程能真实反映籽粒灌浆进程.旋耕条播、机械撒播耕作深度相同,各阶段灌浆速率较一致,渐增期、快增期、缓增期均低于深松条播和免耕条播,但二者株行配置方式不同,机械撒播渐增期略高于旋耕条播,快增期、缓增期均低于旋耕条播,但3个阶段灌浆持续期分别比旋耕条播高0.05、0.57 d和0.71d.耕作、种植方式主要通过影响籽粒灌浆速率和灌浆持续天数影响粒重,耕作方式对灌浆速率影响大,株行配置对灌浆持续期影响明显.耕种方式对强势粒、弱势粒灌浆特性影响效应不同,机械撒播强势粒渐增期灌浆速率高达0.95 mg·d-1·粒-1,持续时间仅为9.95 d,快增期、缓增期灌浆速率仅为2.11 mg·d-1·粒-1和0.59 mg·d-1·粒-1,但持续时间长达12.27 d和15.27 d,强势粒千粒重高达41.65 g,虽然强、弱势粒综合千粒重仅为40.2g,但该模式有效穗数高,经济产量高达7 599.0 kg·hm-2.     

秸秆覆盖对旱地冬小麦灌浆动态及产量的影响

为了研究不同秸秆覆盖量处理下冬小麦籽粒灌浆的动态及产量变化,在渭北旱塬设置秸秆覆盖量9000 kg/hm2(SM9)6、000 kg/hm2(SM6)3、000 kg/hm2(SM3)及无覆盖(CK)4个处理进行旱地冬小麦栽培试验。结果表明,在灌浆渐增期,不同处理的灌浆速率表现为:CKSM3SM6SM9;速增期和缓增期灌浆速率大小为:SM3SM6CKSM9。SM9灌浆持续时间长,较CK多6 d,SM6、SM3与CK灌浆持续时间近乎一致。在灌浆速增期和缓增期,覆盖处理的灌浆贡献率均大于CK,在渐增期则均小于CK。相对于CK而言,覆盖一年后3 000 kg/hm2处理提高了冬小麦产量,较CK显著增产5.9%,且速增期和缓增期灌浆速率保持较高水平。     

Effect of take-all root infections on nitrate uptake in winter wheat

The effect of take-all root lesions on nitrate uptake of wheat was investigated in two experiments under controlled conditions. Plants were supplied with a nutrient solution labelled with ¹⁵N during stem elongation and flowering to assess the distribution of the isotopic tracer in the different plant organs, and particularly in root segments located on both sides of take-all lesions. The ¹⁵N atom percentage excess measured in root segments located below lesions longer than 1 cm was reduced on average by half compared with that in healthy roots and root segments above lesions, reflecting a reduction in nitrogen uptake by these root segments. This reduction probably resulted from the invasion and breakdown of phloem vessels by the fungus hyphae, interrupting energy supply and thus the uptake process. Severely infected plants showed an increase in the uptake rate per unit of efficient root, which appeared to be a compensatory response to reduction of efficient root biomass in order to satisfy shoot nitrogen demand. However, this compensatory response was insufficient to ensure nitrogen accumulation equivalent to that of healthy plants, as reductions in nitrogen accumulated in roots and aerial parts at flowering were up to 56 and 49%, respectively, for plants with more than 50% of the root system below lesions longer than 1 cm.     

不同耕作方式对冬小麦光合作用产量和水分利用效率的影响

豫西旱地大田条件下,对一次深翻、免耕覆盖、深松覆盖、传统耕作4种耕作方式冬小麦叶面积指数、旗叶光合特性、干物质积累与分配及小麦产量和水分利用效率进行试验分析.结果表明,在小麦生育后期,深松覆盖和免耕覆盖能有效延缓小麦旗叶叶绿素降解,维持较高的叶面积指数,改善旗叶光合性能,促进干物质积累,产量分别比传统耕作提高9.26%和10.22%,水分利用效率分别比传统耕作提高10.29%和15.57%.与传统耕作相比,深松覆盖灌浆中后期旗叶光合速率提高了5.48%,Fv/F0值提高了26.72%,Fv/F3m值提高4.88%,ψPSⅡ值和1-qP/qN值与其它耕作方武相比差异不显著.     

Explaining variation in the effects of take-all (Gaeumannomyces graminis var. tritici) on nitrogen and water uptake by winter wheat

Two field experiments, in 1999 and 2000, were used to test whether reductions in root growth and function explained the effects of take-all on crop water and nitrogen uptake. The fungicide silthiofam was used to manipulate take-all independently of other factors. Soil water content was manipulated from heading to determine effects on disease progress and resource capture. Epidemic progress was significantly delayed in the presence of silthiofam, leading to reductions in disease in both experiments. Effects of silthiofam were reduced by increasing soil water late in the season, although only in 2000 did increased soil water content have a direct effect, leading to a higher rate of disease increase. Higher levels of disease in the absence of silthiofam did not affect root growth as measured by total root length density (TRLD), but did lead to significantly reduced healthy root length density (HRLD, a measure of functional roots) in both experiments. Only in 2000 were there any significant effects of increased take-all on water and nitrogen uptake. This was attributed to the higher TRLD in the (1999) crop, which allowed HRLDs to be maintained above a critical threshold (where water and nitrogen uptake start to be severely affected) despite loss of functional root to disease. The effects of take-all on nitrogen uptake were more likely to affect crop canopy size and duration than the relatively small effects observed on water uptake. Increasing soil water content allowed the crop to take up more water in absolute terms despite, in 2000, increasing levels of disease and reducing HRLD.     

Assessment of the profile of powdery mildew and its damage function at low disease intensities in field experiments with winter wheat

Damage by mildew to winter wheat was studied in 11 field experiments in the Netherlands. Damage is described by the simple function: –0.013 (SE=0.003) kg are^–1 per pustule-day of mildew per leaf, from second node stage to early dough at yield levels of 70 to 90 kg are^–1, in diseasefree plots. No deviations from linearity at disease stresses from zero to two thousand pustuledays per leaf were observed. Years, cultivars or soil types did not affect the damage function significantly. The effects of mildew on some yield components were suggested.Mildew profiles in untreated plots could be described by the equation: CM=CLA^b, in which CM and CLA are the cumulative pustule number and the cumulative leaf area, respectively, calculated both from top to bottom of the canopy, and totals standardized at unity. Estimates of the gradient parameter b aveaged 3.4 (SE=0.9). Observed differences in steepness of the profiles did not affect the damage function significantly.Samenvatting Opbrengstderving van wintertarwe door meeldauw werd bestudeerd in 11 veldproeven in Nederland. De schade bedroeg gemiddeld 0.013 (SE=0.003) kg are^–1 per puistdag meeldauw per blad, vanaf het tweede-knoop stadium tot begin deegrijp bij opbrengstniveaus van 70 tot 90 kg are^–1, in de blanco. Bij een ziektestress van 0 tot 2000 puistdagen meeldauw per blad werd geen afwijking van een rechtlijnig verband gevonden. De schaderelatie werd niet significant beïnvloed door de verschillende jaren, rassen of grondsoorten. Het effect van meeldauw op enkele opbrengstcomponenten werd aangetoond.Meeldauwprofielen in de onbehandelde veldjes konden worden beschreven met de vergelijking: CM=CLA^b, waarin CM het cumulatieve aantal puistjes is en CLA het cumulatieve bladoppervlak, beide berekend van bovenin het bladerdek naar beneden, de totalen gestandaardiseerd op één. De gradiënt parameter b bedroeg gemiddeld 3.4 (SE=0.9). Waargenomen verschillen in steilte van de meeldauwprofielen beïnvloedde de schaderelatie niet aantoonbaar.     

Effects of preceding crop,sowing date,N fertilization and fluquinconazole seed treatment on wheat growth,grain yield and take-all

Journal of Plant Diseases and Protection - The soilborne fungus Gaeumannomyces graminis var. tritici (Ggt) causing take-all in wheat, barley and rye is regarded as the most important disease on...     

局部灌水方式对冬小麦产量与水分利用的影响

以根系对土壤水分的吸收利用规律、土壤养分在土层中的分布规律和农田土壤蒸发特征为基础,研究局部不同节水高产灌水方式,是解决水肥异位问题和实现“浇作物”的新尝试。2000～2002年连续两年的试验结果表明,测坑内灌溉5水的处理与筒栽灌溉7水的处理有最高的产量和千粒重,适宜的灌水量是30mm。提高作物产量和水分利用效率的灌溉方式应该是灌水集中在作物主要根系分布层,实施高频局部灌溉。     

The effect on yield of mixtures and sequences of herbicides for the control of Alopecurus myosuroides Huds. and broad-leaved weeds in winter cereals

Mixed infestations of Alopecurus m yosuroides Huds. and broad-leaved weeds in winter cereals were controlled with a commercial formulation of ioxynil + bromoxynil + mecoprop. used in mixtures or as sequences with isoproturon or clofop-isobutyl. As well as controlling A. myosuroides the mixtures, applied in the autumn, gave good control of Veronica persica Poir., Galium aparine L. Lilhospermum arvense L. and Viola arvensis Murr. weeds which were resistant to isoproturon used alone. A. myosuroides had the major influence on crop yield in three experiments. High infestations of A. myosuroides reduced the broad-leaved weeds so that crop yields were only slightly improved when all the weeds were controlled compared with the control of A. myosuroides alone. In the remaining experiment. V. persica was very competitive with wheat; additional control of A. myosuroides improved yields considerably. Ioxynil + bromoxynil + mecoprop gave better final control of broad-leaved weeds when applied in the spring rather than the autumn but the sequence of a spring application following isoproturon or clofop-isobutyl in the autumn did not improve yields compared with the mixtures applied in the autumn. In all experiments, the highest yields were obtained from controlling both A. myosuroides and broad-leaved weeds in the autumn, provided that good control of A. myosuroides was obtained.