Field tests of Trichoderma harzianum Rifai aggr. as a biocontrol agent of seedling disease in several crops and Rhizoctonia root rot of sugar beet

In field studies, mean stands of crops of snapbean, field corn, pea, soybean, and squash in New York were somewhat greater from seeds treated with conidia of Trichoderma harzianum applied in a Methocel slurry than from non-treated controls; however, stands were generally poorer than those from captan-treated seed. The biocontrol agent and captan had little effect on kidney bean and sweet corn since these crops are only slightly susceptible to seedling disease caused by Pythium spp. which were present in the field. In Colorado fields also infested with Pythium spp., stands of sugar beet from T. harzianum-treated seed (Pelgel slurry) tended to be greater than those from non-treated seed and equal to those from maneb-treated seed, but differences were not significant. In Colorado, Rhizoctonia solani, cause of root rot, was also present in the soil. A combined analysis of variance of treatments across 2 years showed that a preplanting-incorporated in-row application of T. harzianum in a wheat-bran carrier or a maneb seed treatment slightly, but significantly, reduced the severity of Rhizoctonia root rot in sugar beet as compared with the non-treated control. Seed treatments with T. harzianum had little or no effect. In plots where the agent was applied to the soil, numbers of Trichoderma propagules increased 600-fold by harvest; where maneb seed treatment was used, they increased only fivefold. Densities of the agent remained the same or decreased in plots where Trichoderma was used as a seed treatment.     

基于高通量测序技术分析不同耕作方式下水稻根际土壤真菌多样性

为研究不同耕作方式下水稻根际土壤真菌群落多样性,本研究以旋耕、免耕和粉垄耕作处理的水稻根际土壤为研究对象,采用高通量测序技术分析了真菌群落结构和多样性,并结合土壤环境因子进行相关性分析。结果表明：3种耕作处理水稻根际土壤中优势菌门为子囊菌门、接合菌门、担子菌门和球囊菌门,优势菌属为镰刀菌属、被孢霉属、Pyrenochaetopsis、柄孢壳属、毛壳菌属、支顶孢属、隐球菌属、Westerdykella、顶囊壳属、绿僵菌属。接合菌门和被孢霉属、支顶孢属、隐球菌属、顶囊壳属真菌相对丰度在不同处理间差异显著。Alpha多样性指数分析显示,3种耕作处理间无显著差异。PCoA分析表明,不同耕作处理下的土壤真菌群落分布特征存在明显差异。冗余分析表明前两个排序轴共解释了3种耕作处理间土壤真菌群落变化的87.46%。相关性分析显示,土壤pH与接合菌门真菌丰度呈极显著正相关关系,土壤速效磷、碱解氮和有机质含量与接合菌门真菌丰度呈极显著负相关关系,土壤速效磷与担子菌门真菌丰度呈显著正相关关系。综上表明,短期不同耕作方式处理下水稻根际土壤真菌群落结构和多样性存在差异,不同处理下真菌群落分布受土壤pH值、有机质、碱解氮和速效磷影响。     

Plant protection in spring cereal production with reduced tillage. II. Pests and beneficial insects

In five field experiments run for four years the infestation of pests and the activity of carabids and staphylinids were compared in autumn ploughed and reduced tillage (no-tillage or spring harrowing) plots. Differences were generally most evident in experiments with no-tillage. Weed cover was denser in reduced tillage, and could explain much of the differences. The agromyzid Chromatomyia fuscula was most common in autumn ploughed plots, probably due to healthier plants. Thrips numbers were correlated with grain quality in no-tillage plots. Field slugs were most common in reduced tillage, and were positively correlated with weed cover. Generally, more carabids and staphylinids were caught in reduced tillage. This was especially true for Amara-species and Loricera pilicornis, Philonthus cognatus and Tachinus signatus, which also were positively correlated with weed cover. Aloconota gregaria, Bembidion quadrimaculatum, B. lampros, Harpalus rufipes and Trechus quadristriatus were more common in autumn ploughed plots, several of them preferring open soil.     

The use of minimum tillage plus herbicides in potato production

There has been a marked increase in the use of herbicides in potato production. In many cases growers have simply added herbicides to their existing weed control program with little or no reduction in tillage. On Long Island six or more separate mechanical operations may be used by growers to control weeds. The current paper summarizes 3 years’ results with various tillage — herbicide combinations carried out under widely varying levels of weed infestation. Under conditions of low to moderate infestation good results were obtained with one to two tillage passes plus the use of an herbicide. The use of an incorporated herbicide such as EPTC plus a single hilling operation as early as ground-brack was satisfactory. Greening of tubers was not appreciably increased by this or other early hilling practices. Fields with severe weed infestations required two to three tillage treatments plus an herbicide application. No yield reduction occurred from these treatments, with some indication of a trend in the opposite direction.     

Dry pea (Pisum sativum L.) yielding and weed infestation response,under different tillage conditions

Legume-crops are considered important components of conservation farming and also of the conventional system in recent years. However, a lack of studies reflect a priority need for primary research into food legumes and their impact on farming systems, which is currently at secondary level to cereals in terms of investigation. The present field study was undertaken to compare the effects of different tillage systems on yielding and weed infestation of pea. Tillage treatments employed included conservation (minimum-tillage and zero-tillage) and conventional system (conventional-tillage) under semi-arid conditions. The weather had a marked influence on yielding and weed diversity of pea crop over the study period. Tillage system had no effect on pea grain yield and the yield components of pea. We observed, with scarcer annual rainfall, lower values of grain yield, straw biomass, harvest index and yield components in minimum-tillage plots. This could be attributable to an increase of the weed community favoured by rooting conditions. Weed density and diversity indices (Shannon and Evenness) presented the highest values in minimum tillage system. Particularly, we observed that decreasing tillage favoured the increase of one annual grass weed (Lolium rigidum Gaudin). Our results highlight the research on weed species associated with low-input systems.     

耕作措施对燕麦田土壤水分、温度及出苗率的影响

为明确耕作措施对旱作燕麦田土壤水分、温度及出苗率的影响,以燕麦品种坝莜1号为材料,于2011-2013年在内蒙古清水河县进行耕作措施比较试验。结果表明,保护性耕作措施(免耕、春松和秋松)能明显减少农田冬闲期土壤水分散失,提高0~100cm土壤贮水量。在燕麦苗期,免耕、秋松、春松和秋翻处理的0~100cm各土层2年平均土壤含水量较春翻分别高出11.55%、9.66%、7.04%和1.22%。深松与免耕较翻耕在土壤温度较高时有一定的降温作用,在土壤温度较低时又具有一定的升温效应。燕麦出苗率表现为免耕春翻春松秋翻秋松。燕麦出苗率与苗期0~10cm土层土壤含水量呈极显著正相关,与其他土层土壤含水量和耕层土壤温度无明显相关性。综合考虑土壤水分、温度和出苗率,以免耕处理效果最佳。     

Effect of pythium root rot on yield of white bean, Phaseolus vulgaris L.

The effects of Pythium paroecandrum and P. ‘spherical’ on seed yield of white bean (Phaseolus vulgaris L.) were determined under field conditions. Fenaminosulf (Lesan) applied as a soil drench selectively suppressed Pythium populations in soil and increased seed yields by 47% in 1976 and by 33% in 1977. Fumigation of soil with DD-MIT (Vorlex), a commercial mixture of methyl isothiocyanate, dichloropropenes and dichloropropanes, reduced populations of Pythium and Fusarium in soil and increased seed yields by 79% in 1976 and by 29% in 1977. The combination of fenaminosulf and DD-MIT produced the greatest reductions in soil populations of Pythium and Fusarium and increased seed yields by 65%. Pythium paroecandrum and P. ‘spherical’ were associated with feeder-root necrosis and were the only bean-root pathogens detected at the experimental site. In this study, losses in seed yield of white bean due to Pythium root rot were estimated to be 44% in 1976 and 39% in 1977.     

水稻富含半胱氨酸类受体激酶家族基因对纹枯病菌和植物激素的响应特征分析

【目的】明确水稻富含半胱氨酸类受体激酶（Cysteine-rich receptor-like kinases,CRK）家族基因对纹枯病菌侵染和植物激素的响应特征,是解析CRK在水稻纹枯病抗性中的功能的重要前期工作。【方法】利用生物信息学方法构建了水稻45个CRK的系统发育树,并利用qPCR分析了它们对纹枯病菌和对植物激素乙烯（Ethylene,ET）、茉莉酸（Jasmonic acid,JA）、水杨酸（Salicylic acid,SA）和细胞分裂素（Cytokinin,CK）等的响应特征,以及在水稻不同组织中的表达模式。【结果】水稻CRK家族可分为4个组,在染色体上成簇或紧密分布的CRK大部分来自同一组或同一分支。41个CRK响应纹枯病菌侵染,其中17个响应强烈;结合组织表达模式,发现这17个CRK基因中,CRK15、CRK23、CRK24、CRK26、CRK27、CRK28、CRK29、CRK30、CRK31和CRK33等10个基因在叶鞘和叶片中表达较强,暗示这些基因可能参与了对纹枯病的抗性;大部分同一分支的两个同源性较高的CRK对纹枯病菌的响应特征类似, 表明这些CRK基因在调控纹枯病抗性上可能存在功能冗余。40个CRK对3种或4种植物激素均有响应,它们对不同激素的响应存在差异性,说明CRK可能广泛参与这些激素介导的防御信号途径;对JA和SA响应相反的有17个,对JA和SA、ET和JA、ET和SA响应类似的分别有21、21、23个。这不仅反映了ET、JA、SA信号途径间的协同和拮抗作用,也说明这些基因可能参与ET、JA和SA间的交互作用。【结论】鉴定到一些可能参与调控水稻纹枯病抗性的CRK基因,且它们可能在植物激素介导的防御途径中起作用。这为我们进一步探索CRK在调控水稻纹枯病抗性上的功能提供了科学线索。     

半干旱区保护性耕作对旱作春小麦光合特性和产量形成的影响

为探究黄土高原半干旱区保护性耕作提高春小麦产量的光合生理机制,依托黄土高原半干旱区2001年建立的不同耕作措施长期定位试验,于2019年研究了传统耕作(T)、传统耕作秸秆翻入(TS)、免耕秸秆不覆盖(NT)、免耕秸秆覆盖(NTS)四种耕作措施对春小麦叶片光合相关性状、干物质积累和产量的影响。结果表明,小麦叶片叶绿素含量和叶面积指数在抽穗期达到峰值,保护性耕作延缓了花后叶片衰老,其中NTS处理的叶片叶绿素含量和叶面积指数在乳熟期均显著高于其他处理;耕作措施对开花期小麦旗叶RuBP羧化酶活性没有影响,但在灌浆期免耕和秸秆还田均提高了RuBP羧化酶活性,其中NTS处理的RuBP羧化酶活性是T处理的1.95倍;秸秆覆盖对小麦旗叶光合速率、蒸腾速率、气孔导度影响显著,NTS处理可有效改善春小麦开花期和灌浆期的光合性能,其中NTS处理的开花期旗叶光合速率、蒸腾速率、气孔导度比T处理分别提高了19.2%、30.7%、23.0%;免耕处理(NT和NTS)下花后干物质积累对籽粒贡献率较耕作处理(T和TS)提高了41.7%,秸秆还田处理(TS和NTS)花后籽粒干物质积累量及花后干物质积累对籽粒产量贡献率较不还田处理(T和NT)分别提高了71.2%和35.7%;NTS处理有效促进了小麦花后干物质积累和转运,显著增加了穗数和千粒重,使产量较T处理提高了18.7%。因此,在黄土高原半干旱区应用免耕秸秆覆盖的保护性耕作措施可促进春小麦旗叶花后光合作用、干物质积累及其向籽粒分配,延缓灌浆后期叶片衰老和叶绿素降解,协调和优化光合性能、光合时间、光合面积之间的关系,从而提高产量。     

Multi-Year Evaluation of Model-Based Weed Control Under Variable Crop and Tillage Conditions

Abstract

Selecting effective weed management options requires biological, ecological, and economic information. This study compared model-based to standard-herbicide weed control in a corn (Zea mays L.)/soybean [Glycine max (L.) Merr.] rotation that had a long-term history of different tillage and weed management practices. The model integrates weed population dynamics, herbicide efficacies, and economic information to evaluate preplant incorporated (PPI) or preemergence (PRE) weed control options based on weed seed bank size and postem-ergence (POST) strategies based on weed seedling densities. There were fewer weeds in standard-herbicide compared with model-based treatments. No-tillage had the greatest numbers of weeds 3 out of 4 years. Soybean yield was reduced the first year of the study in several treatments receiving model-based weed control and the third year in all model-based treatments. Corn yields were greatest in reduced tillage. Resuits of using model recommendations to control weeds were mixed, with PRE recommendations being insensitive to a common cocklebur (Xan-thium strumarium L.) infestation. Our conclusions agree with those of others that the nature of the weed pressure may be a prevailing influence on the outcome of using weed control recommendations of bioeconomic models.     

海南岛东南沿海地区不同森林类型林地凋落物现存量和养分特征

为揭示热带沿海地区不同森林类型凋落物现存量及其养分元素储存能力的差异,选取林地相邻、生境条件基本一致的青皮林和木麻黄林为研究对象,设置随机样地,采集未分解层、半分解层、已分解层凋落物样品,测定凋落物层现存量和主要养分元素含量、储量及其释放率。结果表明：（1）木麻黄林凋落物层现存量为29.49 t/hm²,是青皮林的2倍,2种林型不同分解层表现为：已分解层>半分解层>未分解层;（2）2种林型不同分解层养分元素含量基本遵循C>N>Mg>K>P的变化模式,随着凋落物分解,青皮林各养分元素含量逐级降低,木麻黄林则因养分元素不同而异,可能因凋落物C含量流失过多出现损失速率大于分解释放养分速率而造成半分解层N、P、Mg的含量相对增加,但均在已分解层含量最低;（3）木麻黄林凋落物层养分储量值为8448.23 kg/hm²,是青皮林的2倍,各分解层凋落物养分元素的储量依次为C>N>Mg>K>P,与养分元素含量变化规律一致,而养分释放率从未分解层（-1.79%、-0.97%）到半分解层（0.65%、1.23%）呈现增加趋势。总之,同一立地条件下,不同林型的凋落物现存量、养分含量及其储量的差异可能与植物叶片生物学特征、微环境条件、微生物种群及活性不同有关。     

Agronomic assessment of Bt trait and seed or soil-applied insecticides on the control of corn rootworm and yield

Corn rootworm (Diabrotica spp.) has become the most concern and widespread insect pest of corn (Zea mays L.) production in North America. Two field experiments were conducted to assess the agronomic and yield performance of transgenic rootworm trait, Bacillus thuringiensis (Bt) Cry3Bb, seed-coating treatment, and a soil-applied insecticide under natural corn rootworm infestation. Experiment 1 compared a conventional corn hybrid with and without insecticide (Force 3G) with its near isoline Bt hybrid from 2003 to 2005, on a clay loam soil. Experiment 2 investigated the same treatments as in Experiment 1 plus an additional seed-coated Poncho treatment on a sandy loam in 2004 and 2005. Rootworm population before the crop anthesis, root node injury and root:shoot dry weight ratio during the early grain filling stage, and stalk lodging and grain yield were determined. Our data showed that rootworm population diminished over the 3 years owing to rootworm displacement and adverse weather conditions. At the clay loam site, both Force 3G and the Bt hybrid significantly reduced the larval populations, root injury and lodging score, and increased root:shoot ratio. Over the 3 years, grain yields of the Bt hybrid were 11–66% greater than the untreated non-Bt isoline hybrid; yield of the non-Bt hybrid treated with Force 3G was also significantly greater than the same untreated non-Bt hybrid in 2 of 3 years. Despite less root node injury in the first rows of non-Bt plants adjacent to the Bt plots was observed, yield benefit of this effect remained to be proven. On sandy loam soil, the larval population was very low and there were no differences in root node injury and plant lodging among all the four treatments in either 2004 or 2005. The yield of the Bt hybrid was up to 10% greater than its non-Bt isoline hybrid treated or not with an insecticide in 1 year. Our data showed that Bt rootworm seed technology was effective to control the rootworm larvae and protected grain yield under severe infestation. Furthermore, our data suggest that some of the gain in Bt hybrid yield may be attributed to the genetic transformation as observed in sandy loam soil experiment. In all cases, corn producers should be aware of the pest history, rootworm pressure in relation to economic threshold, soil type and the expected cost-to-benefit ratio before deciding to adopt any protective measures.     

Effect of a combination of chlorine dioxide and thiophanate-methyl pre-planting seed tuber treatment on the control of black scurf of potatoes

The pre-planting seed tuber treatments of chlorine dioxide (ClO₂), thiophanate-methyl (TPM), and a combination treatment of ClO₂, followed by TPM, were evaluated for control of stem canker and black scurf (Rhizoctonia solani), and storage rots; black scurf, common scab (Streptomyces scabies), dry rot (Fusarium spp.) and silver scurf (Helminthosporium solani) on potato (Solanum tuberosum L.) cv. Kennebec. Field experiments were conducted in two consecutive years, 1999 and 2000, at the Agriculture and Agri-Food Canada Research Farm in Harrington, Prince Edward Island (PEI), Canada. The combination treatment of ClO₂ (200 μg g⁻¹) and TPM (50 g active ingredient100 kg⁻¹ of tubers) significantly (P=0.05) reduced stem canker and black scurf on progeny tubers at harvest and after storage. The low incidence of scab and dry rot in untreated controls hindered the evaluation of the efficacy of the combination treatment and also showed that conditions were not favourable for disease development during this period at Harrington. The combination treatment was not effective on silver scurf in storage. A comparison among control, ClO₂, TPM, and the combination treatment indicates that pre-planting ClO₂ treatment may have killed the majority of the black scurf sclerotia on the tuber surface and that the combination of TPM fungicide treatment following ClO₂ treatment gave protection to progeny tuber by suppressing the growth of the R. solani. A higher marketable yield was observed in the combination treatment as compared with the untreated control. Phytotoxicity was not observed in tubers treated with the combination treatment.     

秸秆覆盖深松对夏玉米花后穗位叶衰老和产量的影响

采用4种保护性耕作模式(深松覆盖、深松不覆盖、免耕覆盖、免耕不覆盖)在河南西平进行了3年田间试验,研究不同处理对玉米花后不同时期穗位叶超氧化物歧化酶(SOD)和过氧化物酶(POD)活性、丙二醛(MDA)含量的影响。结果表明,与其他3种处理相比,深松覆盖处理下玉米穗位叶一直保持着较高SOD、POD活性,在花后15d、30d显著高于其他处理;深松覆盖花后一直保持着较低的MDA含量,并且显著低于其他处理;深松覆盖处理产量比深松不覆盖、免耕覆盖、免耕不覆盖处理分别高2.17%、6.06%、14.13%,差异达到显著水平。研究表明,深松覆盖在降水较多的豫南雨养区能取得良好的增产效果。     

Response of progeny bred from Bolivian and North American cultivars in integrated management systems for leaf spot of peanut (Arachis hypogaea)

Early and late leaf spot (caused by Cercospora arachidicola and Cercosporidium personatum, respectively) are major yield-reducing diseases of peanut (Arachis hypogaea L.) in the southeastern U.S. Effective suppression of both early and late leaf spot, collectively called ‘leaf spot’, can be reached with integrated disease management (IDM) systems utilizing peanut cultivars with moderate levels of resistance to these pathogens. A Bolivian landrace cultivar, Bayo Grande, and a series of progeny breeding lines were evaluated under two IDM systems consisting of various reduced application fungicide regimes and/or tillage treatments in field experiments over two years. In the absence of fungicides or when averaged across fungicide regimes, Bayo Grande and breeding lines had better leaf spot resistance when compared to cultivars Georgia Green, MDR-98 and C-99R in all experiments across years. The addition of three or four fungicide applications to Bayo Grande and several of the breeding lines suppressed leaf spot to levels similar to those genotypes and Georgia Green under the full regime. Conservation tillage reduced the need for fungicides in most genotypes in both years. Yields were higher for Bayo Grande and the breeding lines compared to Georgia Green in three of the four experiments across years. When compared across genotype, yields were greatest for the full season fungicide regime, except in 2002 when yields were similar for all treatments. Leaf spot severity was reduced in conservation tillage compared to conventional tillage in most varieties in the absence of fungicides. However, yields tended to be lower in conservation tillage treatments than in conventional tillage. Under conservation tillage, yields of Bayo Grande and two of the breeding lines were negatively impacted in one year and were overall lower in the other year. Several of these new Bolivian-derived genotypes show promise for use in a reduced fungicide and/or conservation tillage IDM system with the potential to lessen fungicide use compared to standard production practices while maintaining low leaf spot levels and high yields.     

自然降水条件下耕作方式对小麦生长、产量及土壤水分的影响

为探寻小麦高产节水耕作技术,在2011-2013小麦生长季,通过定位试验,以安徽大面积主推小麦品种济麦22为材料,比较分析了在自然降水条件下秸秆还田+深耕+播后镇压、深松+播后镇压、旋耕+播后镇压、旋耕和复式播种作业5种耕作方式下淮北地区小麦生长发育、产量及土壤水分的差异。结果表明,各耕作处理下小麦田间出苗率均在70%以上,基本可以满足小麦生产对田间出苗的要求。在5个处理中,旋耕+播后镇压处理出苗率最高,达83%;复式播种作业处理的单株次生根数最高,2年在生育后期分别达到24.2和28.9条;旋耕+播后镇压处理2年平均及各年度的籽粒产量均最高,分别为8 206.8、8 175.5和8 238.0kg·hm-2,复式播种作业次之,秸秆还田+深耕+播后镇压最低,处理间差异显著。深松和旋耕处理在小麦生育后期0~20cm土层土壤水分含量较低,而40~60cm土层土壤水分含量较高。本试验条件下,旋耕+播后镇压是小麦兼顾高产节水的最优耕作播种方式。     

Development of a formulation of Pseudomonas fluorescens PfALR2 for management of rice sheath blight

Pseudomonas fluorescens isolates that inhibited growth of Rhizoctonia solani, the rice sheath blight pathogen, were isolated from the rhizosphere of different crops. One of the most effective strains, PfALR2, was developed as an antibiotic resistant strain and a peat-based formulation was developed for this bacterium. The effective dose of a peat formulation was assessed for seed treatment, root treatment, soil application and foliar spraying. All individual treatments controlled the disease effectively. However, a combination of all four treatments resulted in the best sheath blight control in the greenhouse. In field trials, application of the peat-based formulation of PfALR2 effectively controlled the disease, increased yield, and efficacy was comparable to that of the commercially available fungicide, carbendazim.     

Effects of cultivar resistance and single fungicide application on rice sheath blight, yield, and quality

The increased number of sheath blight (Rhizoctonia solani)-resistant rice (Oryza sativa) cultivars available will allow producers to use less fungicide and avoid significant reductions in grain and milling yields. Among cultivars currently in cultivation in the southern United States, sheath blight resistance levels range from very susceptible to moderately resistant. A study was conducted to determine the response of cultivars, with different levels of susceptibility, to sheath blight inoculations and fungicide application and to determine the impact of sheath blight disease development on rice yield and quality. Sheath blight epidemics in field plots were initiated by inoculation at the panicle differentiation growth stage in 2006 and 2007. Azoxystrobin at 0.17 kg a.i. ha⁻¹ was applied at mid-boot. Inoculation significantly increased sheath blight severity and incidence and caused yield losses of 8% in moderately resistant cv. Jupiter to 40% in very susceptible cv. Trenasse. Milling yields were affected to a lesser extent. Fungicide treatments reduced sheath blight incidence and severity, regardless of cultivar except in Jupiter. Single azoxystrobin applications were effective in minimizing yield loss due to sheath blight in all cultivars.     

耕作培肥对冬小麦产量构成及叶片生理特性的影响

为了明确豫中麦区合理的耕作培肥模式,研究了该麦区不同耕作深度(耕深30 cm、20 cm)、施无机肥(小麦专用肥,以下称"专用肥")、无机肥混有机肥(鸡粪和饼肥)对冬小麦产量构成和生理特性的影响.结果表明,各处理间单位面积穗数差异不显著,穗粒数差异显著.千粒重浅耕下专用肥配施鸡粪最高,深耕下专用肥配施鸡粪最低,差异极显著;理论产量处理间存在显著差异,深耕下专用肥配施饼肥最高,浅耕下施专用肥最低,耕作施肥对理论产量有显著影响(F=2.946*),施肥对理论产量影响显著(F=5.146*).灌浆中期不同耕作施肥处理对总叶绿素含量影响极显著(F=5.474**)、对NR活性影响极显著(F=7.46**)、对可溶性糖含量影响显著(F=6.168*),总叶绿素含量与NR活性和可溶性糖含量成负相关,与成熟期千粒重成正相关;NR活性与可溶性糖含量成正相关,与成熟期千粒重成负相关;可溶性糖含量与成熟期千粒重成正相关.本研究表明,深耕下专用肥配施饼肥是豫中麦区最好的耕作培肥方式.     

Relationship between F4 Individuals and F5 Lines in Cooking Quality of Rice

Abstract

The response of microarthropod populations to different combinations of conservations! agricultural practices was investigated in two field experiments. In the first experiment, cropping systems with combinations of tillage (conventional or reduced), biocide application (conventional or reduced), and fertilization (chemical or cattle manure compost) were compared. In the second experiment, five treatments including four fallow managements that received different levels of tillage, biocide, and organic matter input from vegetation were compared. The springtail (Collembola) population was higher with less tillage, less biocide application, and more organic matter input in both experiments, and these effects were additive; there was no specific combination of practices that has an interacting effect. The mite (Acari) population was also higher under most conservations! treatments, and a significant interaction effect between tillage and organic matter application was found. A large increase in the Acari population under the combination of reduced tillage and higher organic matter input suggested that beneficial effects of these practices on the Acari community could be increased by integrating these practices. There was no significant correlation between the microarthropod populations and plant cover or soil chemical/physical properties measured. Slight changes in soil environments caused by agricultural practices may affect microarthropod communities substantially even before the changes in soil properties become detectable.