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Allelopathy of weeds on vegetables

Allelopathy of weeds on the growth of vegetables
Ines Rezendes1, Ediane Roncaglio Baseggio1, Leandro Galon1, Daiani Brandler1, César Tiago Forte1, Ignacio Aspiazú2, Milena Barretta Franceschetti1 and Alexandre Ferreira da Silva3
1 Federal University of Fronteira Sul, Erechim, RS, Brazil.
2 State University of Montes Claros, Janaúba, MG, Brazil.
3 Embrapa Milho e Sorgo, Sete Lagoas, MG, Brazil.

The use of allelopathy emerges as an alternative method for weed management in crops, especially in small vegetable producing properties. Thus, the objective of this work was to identify possible allelopathic effects of aqueous extracts of the weeds Cyperus difformis L. (small-flowered nutsedge), Commelina benghalensis L. (benghal dayflower) and Galinsoga parviflora Cav. (gallant soldier) on seed germination and seedling growth of Lactuca sativa L. (lettuce) and Lycopersicum esculentum L. (tomato). Two experiments were carried out in a completely randomized design with five replications, the first with lettuce seeds and the second with tomato seeds submitted to germination in five concentrations of weeds aqueous extracts (0, 25, 50, 75 and 100%). All treatments with aqueous extracts of the three species, at different concentrations, caused a reduction in lettuce and tomato root length. There was a reduction in most of the evaluated variables, and seed germination of the crops had the lowest influence of the extracts. The weeds benghal dayflower, small-flowered nutsedge and gallant soldier showed allelopathic potential on lettuce and tomato crops. This potential allelopathic effect is directly related to the concentration and type of extract from the plant species. In general, it can be noted that the greatest allelopathic effect occurred with the use of small-flowered nutsedge extract, followed by gallant soldier and benghal dayflower.

Highlighted Conclusions
1. Weeds C. benghalensis, C. difformis and G. parviflora show allelopathic potential on the growth of L. sativa and L. esculentum.
2. Highest allelopathic effect is caused by the extract of C. difformis, followed by G. parviflora and C. benghalensis.
3. The potential allelopathic effect of weeds is directly related to the plant species used, as well as to the concentration of the aqueous extract present in the environment. (more…)

Agronomic performance and chemical traits in oat

Associations between agronomic performance and grain chemical traits in oat
Solange Ferreira da Silveira Silveira, Danyela de Cassia Silva Oliveira, Latoia Eduarda Maltzhan, Tiago Corazza, Victoria Freitas de Oliveira, Cristiano Stulp, Henrique Pasqueti Carbonari, Vianei Rother, Maraisa Crestani Haverroth, Luis Carlos Gutkoski, Luciano Carlos da Maia and Antonio Costa de Oliveira
Federal University of Pelotas, Pelotas, RS, Brazil

Great progress has already been achieved in breeding white oats (Avena sativa L.). However, breeders of this species need to make available to the market higher yielding and higher grain quality cultivars. Therefore, it is necessary to optimize the strategies of selection of superior genotypes. The present work aimed to estimate the correlation between traits related to agronomic performance and traits related to chemical composition of white oat grains, seeking to add understanding for the selection of higher yielding genotypes with high nutritional quality. Thirty families from the cross between the cultivars Albasul and UPF 15 were used, and 31 families from the cross between the cultivars IAC 7 and UFRGS 19. Six traits related to agronomic performance and five traits corresponding to the chemical composition of the grains were evaluated. To assess the relationship between the different traits evaluated, simple correlation and canonical correlation analyzes were performed. The results demonstrate the existence of simple correlations between grain chemical constituents and traits related to agronomic performance. The pair-by-pair relationship between traits of these two groups was also observed, but the environmental action strongly interfered with these correlations. The canonical correlation analysis allowed the verification of dependence between the evaluated trait groups where genotypes with higher number of grains per panicle, high mass of one thousand grains, with lower stature and lower number of spikelets, will have lower lipid and total fiber content, but with higher protein contents.

Highlighted Conclusions
1. There is a relationship of dependence between the agronomic performance trait group and the oat grain chemical constituent group.
2. Indirect selection of grains with higher nutritional quality and high agronomic performance will be feasible providing there is a strict control of environmental conditions.
3. Selections that seek superiority in all traits studied will not be possible, given the presence of negative correlations. (more…)

Water hyacinth control

Communications in Plant Sciences, vol 9, p. 129-132, 2019 (2019021)

Control of water hyacinth: a short review

Wilson Roberto Cerveira Junior and Leonardo Bianco de Carvalho*
*Correspondence to:

Abstract: Water hyacinth (Eichhornia crassipes) is an aquatic weed native from South America that invades waterbodies of tropical and sub-tropical sites worldwide. Mechanical, chemical and biological efforts are been used to control water hyacinth. Each method of control shows advantages and disadvantages. There are no water‐use restrictions associated with mechanical control and it does not require much technical expertise, especially when plants are removed from the waterbody. However, changes in dissolved oxygen and trophic structure can accelerates eutrophication when plants are cut, leading to a subsequent increase in water hyacinth blooms. Chemical control is less labor intensive and expensive than mechanical control, especially at large scales. However, herbicides can kill non‐target algae and non‐target macrophytes, resulting in far reaching ecological impacts. Biological control is an alternative to mechanical and chemical control. It is not labor or equipment intensive, and has the potential to be self‐sustaining. However, host specificity is critical to the success of biological control and the and long-term results can discourage one to use this method. Probably, biological control is the most efficient and safety method for water hyacinth management, especially for long-term results. Mechanical and chemical control are effective for short-term results, but they can seriously impact on ecological conditions of waterbodies.

Highlighted Conclusion
1. Mechanical, chemical and biological methods are efficient to control water hyacinth.
2. Biological control is very efficient and safety for long-term control of water hyacinth.

Keywords: Eichhornia crassipes, Aquatic weed, Macrophyte, Weed control. (more…)

Irrigation management of rice on Meloidogyne graminicola

Communications in Plant Sciences, vol 9, p. 124-128, 2019 (2019020)

Reaction of rice cultivars to Meloidogyne graminicola as a function of irrigation management

Cristiano Bellé*, Rodrigo Ferraz Ramos, Ricardo Rubin Balardin, Tiago Edu Kaspary and Andressa Lima De Brida
*Correspondence to:

Abstract: The objective of this study was to evaluate the reproduction of Meloidogyne graminicola in 22 cultivars of rice used in the southern region of Brazil according to the irrigation management. The design was completely randomized in a factorial scheme, being the factor A: rice cultivars and factor B: irrigation management (dry and flooded). The rice cultivars were kept individually in pot with sterilized substrate and inoculated with 5,000 eggs and juveniles (second stage – J2) of the nematode. Plants to rice cultivate BRS IRGA 410 was inoculated with M. graminicola and were used as controls. At 60 days after inoculation, the root system of each plant was evaluated number of galls (NG), number of nematodes per gram root (NNGR) and the reproduction factor (RF). The results demonstrate that M. graminicola can parasitize and develop in different rice cultivars that are commonly used in commercial crops in the Southern region of Brazil, and all cultivars evaluated were classified as susceptible to this nematode (FR> 1.00). The cultivation system under flood conditions showed significantly lower values for the NG, NNGR and RF.

Highlighted Conclusions
1. The cultivars BRS Firmeza, IRGA 421, IRGA 423, IRGA 424, IRGA 436, IRGA 428 CL, IRGA 429, Inov CL, Avaxi CL, BRS Catiana and SCS121 CL showed the lowest RF in the flooded crop.
2. The use of cultivars with lower nematode RF in early flood cropping systems is a strategy indicated to reduce the population and the potential for damage caused by M. graminicola in areas with rice crop.

Keywords: Root-knot nematodes, Reproduction, Susceptibility, Oryza sativa. (more…)

Azospirillum brasilense and macronutrients in brachiaria

Communications in Plant Sciences, vol 9, p. 115-123, 2019 (2019019)

Azospirillum brasilense and macronutrients in the initial establishment of brachiaria

Tauane Santos Brito*, Tatiane Eberling, Leila Alves Netto, Giovana Ritter, Renan Pan, Daniele Cristina Schons Eckhardt and Vandeir Francisco Guimarães
*Correspondence to:

Abstract: Pasture production needs sustainable technologies, associating correct fertilization techniques that allow its maintenance aiming at productivity for quality animal feed production. The objective was to evaluate the initial responses of the inoculation with Azospirillum brasilense associated to macronutrients in Brachiaria brizantha cv. ‘Xaraés’. In pots filled with Oxisoil, with combinations of macronutrients as formulates (10-10-10; 20-10-10; 10-20-10; and 10-10-20) associated or not to inoculation with growth promoting bacteria A. brasilense, the experiment was conducted in a randomized blocks design, with four replicates. At 10, 20 and 30 days after emergence the plants were evaluated for number of leaves, length of the biggest leaf, aerial length, number of tillers and chlorophyll relative content. At 30 days after emergence, plants were evaluated for dry mass of roots and aerial part, root length, leaves content of nitrogen, phosphorus and potassium. The use of the formula 10-20-10, in the absence or presence of inoculation with A. brasilense, increased the leaves initial development of plants of B. brizantha cv. ‘Xaraés’. The formula 10-10-10, in the absence and presence of bacterial inoculation, resulted in plants with lower foliar development up to 30 days after emergence.

Highlighted Conclusion
The nutritional availability influences in the initial development of seedlings of B. brizantha cv. ‘Xaraés’.

Keywords: Nitrogen, Phosphorus, Potassium, Pastures, Growth promotion. (more…)

Phenology and phytomass of Crotalaria incana

Communications in Plant Sciences, vol 9, p. 108-114, 2019 (2019018)

Phenology and phytomass of Crotalaria incana L. in the Eastern Amazon, Brazil

Renata Thaysa da Silva Santos*, Mailson Freire de Oliveira, Vandeilson Belfort Moura, Yanna Karoline Santos da Costa and Rafael Gomes Viana
*Correspondence to:

Abstract: Crotalaria incana presents alkaloids that, when ingested by ruminants, culminates in the death of the animals. Given the problems surrounding the presence of the plant in pasture areas, the objective of this research was to determine the phenology and development of C. incana plants under controlled conditions in the Eastern Amazon. The experimental design was completely randomized with four replications and eight treatments. The treatments consisted of plant collection times, from 20 to 160 days after plant emergence. The following parameters were evaluated: number of leaves, leaf length, plant height, number of flowers, number of pods, number of seeds per pod, total number of nodules and nodule viability, in addition to dry weight of shoots, roots, flowers and pods. Data were undergoing regression analysis and simple linear Pearson correlation. The vegetative and reproductive phase lasted until 60 and 140 after emergence, respectively. Plant management should be performed within 80 days of emergence.

Highlighted Conclusions
1. The vegetative state lasts up to 60 days after emergence; at this interval, the species can be incorporated into the soil without risk of increasing the emergence flow of the plant.
2. Control of the species on pasture should be performed before 80 days after emergence.

Keywords: Green manure, Control, Shakeshake, Pasture. (more…)

Sources of N and K affecting wheat diseases

Communications in Plant Sciences, vol 9, p. 100-107, 2019 (2019017)

Nitrogen and potassium sources of fertilizers may affect wheat blast and Fusarium head blight under favorable weather conditions

Sérgio Ricardo Silva*, Adriano Augusto de Paiva Custódio, José Salvador Simonetto Foloni and Manoel Carlos Bassoi
*Correspondence to:

Abstract: Wheat blast (WB) and Fusarium head blight (FHB) are important wheat spike diseases in South America. There is evidence that the severity of these diseases is influenced by soil fertilization. The effects of nitrogen (N) and potassium (K) sources of fertilizers and phenological stages for topdressing fertilization on these spike diseases were evaluated during the 2015 and 2016 winter seasons in an endemic area for these diseases in Brazil. Two distinct field experiments were carried out, one focusing on N sources and the other on K sources. The experimental design was a complete randomized blocks, with four replicates, and the treatments were disposed in a 2 x 3 x 3 factorial: two wheat genotypes (BRS Gaivota and BRS Gralha-Azul), three sources of N or K, and three phenological stages for fertilization. The WB and FHB severities in BRS Gralha-Azul were higher than that in BRS Gaivota. FHB severity was lower when N was applied in the booting stage than in flowering. The sources of K influenced FHB severity, which was higher when K chloride was applied, compared with K nitrate. The weather condition was the determining factor in the wheat expression to WB and FHB diseases, followed by genotype resistance.

Highlighted Conclusions
1. Nitrogen and K sources of fertilizers and the phenological stages for N and K fertilizations do not play a significant role on wheat expression to WB and FHB.
2. Weather condition is the determining factor in the wheat expression to WB and FHB, followed by genotype resistance.

Keywords: Triticum aestivumMagnaporthe oryzae Triticum pathotypeFusarium graminearum, Wheat spike diseases, Nutrient-plant disease interaction. (more…)

Soybean responses to soil micronutrient fertilization

Communications in Plant Sciences, vol 9, p. 93-99, 2019 (2019016)

Nutritional and morphophysiological responses of soybean to micronutrient fertilization in soil

Rubens Ribeiro da Silva*, Larissa Urzêdo Rodrigues, Rodrigo Ribeiro Fidélis, Álvaro José Gomes de Faria and Vitor L. Nascimento
*Correspondence to:

Abstract: Micronutrient fertilization is essential to meet the nutritional deficiency of plants, providing the full development of crops. The aim of this work was to evaluate the effects of fertilization with micronutrients applied in the soil on the nutrition and morphology of soybean plants. The experimental design was completely randomized, with four replications. The treatments consisted of fertilization with micronutrients applied to soil to reach three levels of availability of B: low (<0.15 mg dm-3 – control), good (0.61 mg dm-3) and high (> 0.90 mg dm-3). For this, the following values were applied: 0.00 (control), 56.67 and 211.11 kg ha-1 of the fertilizer containing 1.8% B, 0.85% Cu, 2% Mn and 9% Zn. Fertilization with the good and high treatments did not affect the uptake of B, but increased the Cu and Mn content, and reduced the Zn content in the plants. Higher plants with greater leaf expansion were observed in the high treatment, however, this did not influence the soybean grain yield. In the control, the physiological activity revealed smaller A, whereas gs and Ci were more effective; reverse effect was observed with high treatment. Fertilization with micronutrients in the soil affects the nutritional status and the photosynthetic activity of the plants due to the imbalance in the concentrations of B, Cu, Mn and Zn supplied with the fertilizer, reflecting in the absence of gains in the production of soybean grains.

Highlighted Conclusions
1. Fertilization with micronutrients in the soil using as criterion the reach of three levels of availability of B does not increase the production of biomass and grains, despite ensuring foliar contents of B (Ȳ= 40.40) and Cu (Ȳ= 23.06) suitable for soybean cultivation in the Cerrado.
2. The inequity in the concentrations of B, Cu, Mn and Zn supplied with fertilizer affects the physiological performance of soybean plants.

Keywords: Glycine max L., Low solubility fertilizer, Plant nutrition, Photosynthesis. (more…)

Association of fungicides on Puccinia triticina and wheat

Communications in Plant Sciences, vol 9, p. 88-92, 2019 (2019015)

Association of multisite and site-specific fungicides in the control of Puccinia triticina and its effects on wheat yield

Deivid Sacon, Aline Netto, Alessandra Gallina, Eduardo Silvestrini Tonello and Paola Mendes Milanesi
*Correspondence to:

Abstract: The wheat (Triticum aestivum L.) crop has great importance in the national context, the diseases are one of the main factors of losses, which emphasizes the importance of the pest system Triticum aestivum L. x Puccinia triticina Eriks. The aim of this study was to evaluate the efficiency of the combination of site-specific and multisite fungicides in the control of wheat leaf rust and its effects on crop yield. The evaluated treatments were: Control (absence of fungicide application); T + P (trifloxystrobin + prothioconazole); P + F (pyraclostrobin + fluxapyroxad); T + P + Mb (trifloxystrobin + prothioconazole + mancozeb); P + F + Mb (pyraclostrobin + fluxapyroxad + mancozeb) and Mb (mancozeb). Greater control of the disease was observed with the association of fungicides, there is a correlation between control and crop productivity, especially in harvest with greater severity of the disease.

Highlighted Conclusions
1. At low severity the wheat leaf rust does not present damage on crop productivity.
2. The association of multisite and site-specific fungicides increases the disease control effect.
3. The application fungicide program with the association of different a.i. maintains the crop yield potential.
4. The disease control has a positive effect on the yield components, on the other hand, the AUDPC presents a negative correlation.

Keywords: Leaf rust, Mancozeb, Chemical control. (more…)

Crop and soil management on soil resistance

Communications in Plant Sciences, vol 9, p. 84-87, 2019 (2019014)

Crop rotation and soil scarification: impacts in the soil penetration resistance

Alexandra da Silva Martinez*, Edleusa Pereira Seidel, Renan Pan, Tauane Santos Brito, Wesler Meiners Caciano and Leticia Gabriela Ertel
*Correspondence to:

Abstract: TThe objective of the present study was to evaluate the soil penetration resistance of an Oxisoil under a crop rotation system with mechanical and/or biological scarification. A randomized block design, with four replicates, was used, with the following treatments: sowing of a mix of forage radish and black oat followed by mechanical scarification right after it was sowed; sowing of a mix of forage radish and black oat without mechanical scarification; sowing of maize second crop and scarification right after its harvest; sowing of maize second crop with sowing of buckwheat right after its harvest; sowing of maize second crop (control). All treatments were followed by the sowing of soybean in October 2018. It was evaluated, in five spots per plot, the soil penetration resistance in the 0-40 cm depth, with the digital penetrometer Falker® PLG 1020. All treatments presented a reduction in the soil penetration resistance, with values inferior to 2.00 MPa, which is the critical limit for most crops. In all treatments tested, the penetration resistance tended to equality in the depth of 40 cm.

Highlighted Conclusion
The mechanical scarification can be used to increase the soil water infiltration since results in improvements in the soil physical properties if performed right after the mix of forage radish and black oat was sowed or right after the maize harvest.

Keywords: Winter cover crops, Soil decompression, Soil and water management, Soil and water conservation. (more…)