Intensity of angular leaf spot and anthracnose on pods of common beans cultivated in three cropping systems

Abstract

With the purpose to evaluate the intensity of angular leaf spot (ALS) and anthracnose (ANT) on pods, nine genotypes of common bean were planted in three cropping systems: monocrop (MC), monocrop grown on trellises (MCT), and intercrop with maize (ICM). In MC, beans were planted 0.5 m apart. Trelisses were set up with 1.8 m high bamboos and beans were sown 0.65 m apart. In ICM, beans were planted simultaneously with maize and in its rows. This cereal was sown 1.0 m apart with four plants per meter. Each cropping system was an independent trial installed close to each other. Climbing genotypes of beans most susceptible to ALS had less diseased pods in ICM than in both MC and MCT, but the less susceptible genotypes, regardless of their growth type, as well as the susceptible bush and semiclimbing genotypes, were similarly attacked by ALS in the three systems. ANT on pods of the susceptible bean cv. Pérola was less intense in MCT than in MC, and less intense in ICM than in MCT. ANT seed transmission was 11 %, 9.1 %, and 4.4 % when seeds come from MC, MCT, and ICM, respectively. Index terms: Phaeoisariopsis griseola, Colletotrichum lindemuthianum, Phaseolus vulgaris, seed transmission. RESUMOCom o objetivo de avaliar a intensidade da mancha-angular (MA) e da antracnose (ANT) em vagens, nove genótipos de feijão foram plantados em três sistemas de plantio: monocultivo (MC), monocultivo com tutoragem artificial (MCT) e consórcio com milho (CCM). No MC, o feijão foi semeado no espaçamento entre fileiras de 0,50 m. Para o MCT, utilizaram-se varas de bambu formando "Vs" invertidos com 1,8 m de altura, nos quais foi mantido o espaçamento entre fileiras de 0,65 m na base. No CCM, o feijão foi plantado simultaneamente ao milho e em suas fileiras. Esse cereal foi semeado no espaçamento de 1,0 m, com quatro plantas por metro. Cada sistema de cultivo foi um ensaio independente, todos instalados na mesma área. Os genótipos trepadores mais suscetíveis à MA apresentaram menos vagens doentes no CCM que no MC e MCT, mas os genótipos menos atacados pela MA, independentemente do tipo de crescimento, como também os outros genótipos suscetíveis de porte anão e semitrepador, foram infectados de forma semelhante nos três sistemas de plantio. A ANT nas vagens do cv. Pérola foi menos intensa no MCT que no MC, e menos intensa no CCM que no MCT. A transmissão da ANT pela semente foi de 11 %, 9,1 % e 4,4 % quando as sementes foram colhidas no MC, MCT e CCM, respectivamente. Termos para indexação:Phaeoisariopsis griseola, Colletotrichum lindemuthianum, Phaseolus vulgaris, transmissão por semente.

Severity Evaluation Methods in Common Bean Recurrent Selection Programme for Resistance to Angular Leaf Spot

“…The number of studies that involve evaluation of ALS on pods are few in the literature, in spite of the symptoms of ALS being observed mainly on leaves and pods of common bean (Vieira et al. ; Borel et al. ).…”

“…The number of studies that involve evaluation of ALS on pods are few in the literature, in spite of the symptoms of ALS being observed mainly on leaves and pods of common bean (Vieira et al 2009;Borel et al 2011). Borel et al (2011 observed that the reactions to ALS on leaves and pods are controlled by different genes.…”

Potential and Advantages of Maize-Legume Intercropping System

“…The intercropping system has also an impact against disease management, because in mixture of crops functional diversity is created that checks population increase of pathogen. Some diseases of legume crops like angular leaf spot (Phaeoisariopsis griseola) of beans and ascochyta blight (Mycosphaerella pinodes) were observed with less severity when these were intercropped with maize [46,47] than pure stand of legumes. Reduction of pest-disease incidence not only saves the crop loss and better yield but also assures less use of chemicals for plant protection and thus minimizes the chance of pollution in crop ecology.…”

Intercropping enhances the farmland ecosystem services

“…25% -40% [8] 。 图 1摇 农业生态系统的服务功能涵义 [19] Fig. 1摇 Values of agro鄄ecosystem services [19] 以往的研究主要通过土地当量比,对间套种植提高资源利用效率,提升生产服务功能进行评价 [20鄄 23] 。 土 地当量比可以表示为 [10] : [22] 。 已有 报道,间套种植由于作物对光照的竞争而形成适宜其光截获的冠层结构 [25鄄 26] ;由于对地下水分和营养的竞 争,导致两作物根系的分布呈明显的" 偏态冶 不均衡分布 [27] ,共生物种根系的差异性分布从而形成了适宜吸 的引入能够降低土壤容重和通透阻力,促进间套作系统根系的生长发育 [28] 。 2) 改善土壤化学性质 [44] ,提高 微生物 活 性 和 土 壤 有 效 氮 含 量 [45] , 改 变 农 田 生 态 系 统 土 壤 的 N、 P 等 营 养 元 素 在 土 壤 中 的 转 化 和 转 移 [43, 46鄄 47] ,从而提高肥料的吸收和利用效率。 3) 豆类植物根系分泌物还可以酸化根际土壤,促进难溶性土壤 磷的活化及玉米对磷的吸收利用 [8] 。 4) 间套作农田土壤氮素的淋溶和挥发等流失会适当的降低 [43,48] ,这也 能够使土壤系统内更多的氮素被有效利用。 5) 豆科植物与固氮微生物形成根瘤共生体进行固氮作用也能够 有效提高系统内的氮素含量 [45] 。 表 1摇 不同间套作种植土地当量比 [10, 22, 30鄄 42] Table 1摇 Land Equivalent Ratio in different intercropping systems [10, 22, 30鄄 42] 作物类型 [4] 。 有研究表明,间套作农田 里具有数量较高的害虫天敌,能够有效的控制害虫的数量及其对作物的危害,从而减少杀虫剂的使用 [9] 。 如 Risch 对已发表的 150 篇大田实验结果进行总结发现,所涉及到的 198 种作物害虫丰富度在间套作系统的表 现为:其中的 53% 下降,18% 呈上升趋势,9% 无显著变化,20% 表现为不确定 [49] 。 间套作对害虫的控制机制 主要表现在两个方面( 图 2) :首先,间套作改变了寄主植物的邻居和小气候环境,如间套作系统内部温度降 低、湿度增大、光照下降将直接影响到害虫的生长发育 [50] 。 再者,间套作增加了害虫的天敌数量,如大豆、豌 豆和豇豆等豆类与玉米间作套种能够显著降低花蓟马、黑蚜、白蚁等害虫的密度及其对豆类及玉米的危害,这 主要就是由间套作增加了害虫的天敌数量所引起 [51] 。 间套作对农田生态系统病害的发生和传播的控制也有较多的报道 [16,52] 。 Zhu 等的研究表明,易发病水 稻品种与抗病性品种间作套种,则易发病水稻枯萎病发病率可下降 94% ,作物产量提高 89% [16] 。 小麦与天 蓝苜蓿混间作能够降低全蚀病对小麦的影响;黑麦与小麦间作或大麦与燕麦混间作都能够降低叶片真菌病菌 的发生 [53] 。 与单一栽培相比,豆类和玉米混种或行间作均能够有效的降低白叶枯病和锈病的发生,两种间套 作分别能够降低白叶枯病 23% 和 5% ,锈病 51% 和 25% [54] 。 Vieira 等对菜豆与玉米间套种的研究也发现,间 套种可以减轻叶斑病和炭疽病的发生 [52] [55] ;甘薯与玉米间套作,施肥能够显著的提高作物的叶面积指数、光截获量和营养元素的吸收量,从而抑 制了杂草的生长 [56] ;Saucke 和 Ackermann 对豌豆和亚麻间套作的研究也表明,混间作与单作相比农田杂草盖 度降低了 52% -63% [17] ;单行或双行高粱、大豆间套作能够有效的降低香附子密度(79% -96% ) 和生物量…”