Fábio Luiz de Oliveira

Organic cultivation of okra with ground cover of perennial herbaceous legumes

The management of green manure with perennial herbaceous legumes has emerged as an interesting practice for vegetable production, improving the cultivation environment and increasing crop yields. In the present study we evaluated the organic okra cultivation in soil covered with perennial herbaceous legumes. The treatments consisted of okra grown in bare soil (control) or covered with tropical kudzo (Pueraria phaseoloides), perennial soybean (Glycine wightii), calopogonium (Calopogonium muconoides), Pinto peanut (Arachis pintoi) and Stylosanthes capitata and Stylosanthes macrocephala. A randomized block design with four replications was used. The weeding of legumes was realized before the okra was sown and this allowed the addition of quantities of dry matter, highlighting the potential of tropical kudzo (3.74 t ha-1), perennial soybean (1.55 t ha-1) and peanut (1.30 t ha-1). Okra cropped in soil covered with tropical kudzo and perennial soybean had the weed lowest dry matter accumulation until 150 days after sowing the okra. At 150 days after sowing the okra, only the areas covered with peanut and calopogonium had higher volumes of water in the soil compared to the control. Throughout the harvest, the okra plants grown in soil covered with perennial soybean and tropical kudzo showed the greatest heights. The maximum okra fruit yield (16.23 t ha-1) was obtained by growing okra in soil covered with perennial soybean.

Mulches for yacon cultivation

In Brazil, studies on commercial exploitation of yacon are still scarce. A growing interest in this vegetable has demanded some researches on this crop cultivation management, though. Considering that yacon has a long cycle, which exposes the soil, studies on mulch management will be of great value. We used a randomized complete block design, with five replicates, under different soil mulches for yacon cultivation: two plastic film covers (black and double-sided), four mulches (corn husk, coffee husk in three levels), and the control (bare soil). Plastic mulch can be used for yacon cultivation, considering that the double sided plastic provides greater production of total roots; however, the same yield of the most valued roots was obtained using black plastic. The second highest total productivity and the highest commercial yield in the most valued root classes were obtained using 50 L m-2 of coffee husk as mulch, representing a good alternative for farmers.

LEGUMINOSAS COMO PLANTAS DE COBERTURAS NO CULTIVO DE BANANEIRA EM REGIÃO SEMIÁRIDA

High temperatures and low rainfall characterize the Brazilian semiarid regions. This regional climate demands the adoption of practices that increase the efficiency and sustainability of local farming. This study aimed to assess the ability of two perennial herbaceous leguminous species, calopo and tropical kudzu, to provide permanent soil cover in banana plantations in Jequitinhonha Valley, northeast Minas Gerais state, Brazil. To this end, we evaluated the differences of calopo and tropical kudzu in soil cover capacity and the amount of senescent phytomass deposited on the soil surface, nutrient content in senescent phytomass, as well as their effects on temperature and soil moisture, compared with bare soil in two experimental sites. The results showed that, compared with tropical kudzu, calopo had a higher soil cover capacity and was more effective at increasing organic material and nutrients in the soil owing to the relatively higher amount of senescent phytomass deposited on the soil surface. However, both calopo and tropical kudzu reduced soil temperature and increase soil moisture compared with bare soil. Overall, we concluded that these species can deposit high levels of senescence in the soil, providing several benefits to the cultivation system of banana plants in the semiarid regions.

Genetic diversity of yacon accessions using ISSR markers

Yacon cultivation has been intensified and the investigations of this crop have increased at the scientific, agricultural, and social levels because the roots of yacon show beneficial properties for human health, such as reducing cholesterol and glucose blood levels. Since the investigations involving yacon are very recent, there is little information available in terms of the genetic characterization of the cultivated genotypes. In view of the lack of information on the accessions cultivated in the State of Espírito Santo, Brazil, this pioneering study aimed to characterize 60 accessions cultivated in the state using ISSR yacon markers with emphasis on identifying the genetic diversity among the materials. The 20 ISSR primers used produced a total of 82 fragments, 39.6% of which presented polymorphism. The number of fragments per primer ranged from 1 to 10. The dissimilarity values ranged from 0 to 0.54 according to the Jaccard coefficient. A dendrogram was generated in which the accessions were divided into 3 groups; group 1 contained 58 individuals and groups 2 and 3 had only one individual in each group. The clustering of 58 accessions in a single group shows the low diversity in the materials examined. This low diversity indicates that new genotypes must be introduced in order to promote increased variability, which would minimize the adverse effects caused by biotic and abiotic factors.

Models for estimating yacon leaf area

A exploracao recente de yacon gera demanda de informacoes cientificas que impulsionem o desenvolvimento de tecnologias especificas de manejo e conducao da lavoura. Neste escopo, visando contribuir nos campos fitotecnico e fisiologico, o presente trabalho objetivou ajustar um modelo de estimacao de area foliar em batata yacon, usando medidas nao destrutivas do comprimento (C) e/ou largura (L) de suas folhas. Para tal, 64 plantas representativas da cultura foram coletadas ao acaso, em um campo experimental em pleno crescimento vegetativo. Dessas plantas, 1000 folhas de diversos tamanhos foram tomadas para a construcao e posterior validacao do modelo construido. O modelo logaritmico foi o que apresentou melhor ajuste considerando como variavel independente o produto do comprimento pela largura da folha. Desta forma, encontrou-se que a area foliar em batata yacon, independente do tamanho da folha, pode ser determinada com altas precisoes e acuracia, atraves do estimador AFCL = (-27,7418 + (3,9812CL / ln CL ) .

Occurrence of insects causing injuries to the yacon crop

This research aimed to catalog insects that cause injury to the yacon (Smallanthus sonchifolius, familia Asteraceae) crop, in order to identify those who may cause damage. The study was carried out in Alegre, Espirito Santo State, Brazil. Cultivation began in May 2013 and the harvest was done 180 days later. Three species from the Coleoptera order: Lagria villosa (Coleoptera: Lagriidae); Cerotoma arcuata and Diabrotica speciosa (Coleoptera: Chrysomelidae) and two species from the Lepidoptera order: Spodoptera eridania (Lepidoptera: Noctuidae) and Chlosyne lacinia saundersii (Lepidoptera: Nymphalidae) were observed causing damage to the yacon crop. The caterpillar C. lacinia saundersii, known as sunflower caterpillar, was the most important species, being observed throughout the yacon cycle.