Crotalaria Juncea Research Articles

Calagem, gessagem, culturas de cobertura e adubação nitrogenada em sistema plantio direto: estado nutricional e produtividade do milho

No cerrado, o sistema de plantio direto assume importância devido a não revolver o solo, utilizar culturas de cobertura e preconizar rotação de culturas. Assim, o presente trabalho de longa duração, foi desenvolvido objetivando avaliar nas safras 2015/16, 2016/2017 e 2017/18, o efeito da quantidade de calcário aplicada ao longo do período, culturas de cobertura na entressafra e doses de nitrogênio, sobre os teores foliares de macronutrientes e produtividade de grãos do milho. O trabalho iniciou-se em 2000/01, em área experimental no munícipio de Selvíria, MS, Brazil, em LATOSSOLO VERMELHO distrófico, onde se iniciou o sistema plantio direto. O delineamento foi o de blocos casualizados com três repetições, e os tratamentos dispostos em esquema fatorial 5x2x3, ou seja, 5 combinações residuais de associação de calcário e gesso (6,92 (T1), 11,44 (T2), 7,73 (T3), 10,63 (T4) e 0,81 (T5) t ha-1, onde T3 e T4 receberam em fevereiro/2017, 1,7 t ha-1 de gesso), 2 culturas de cobertura na entressafra (Crotalaria juncea e Pennisetum americanum) e 3 doses de nitrogênio em cobertura no milho (0, 90 e 180 kg ha-1). Os residuais das doses de calagem com ou sem gessagem não alteraram a produtividade de grãos de milho; o incremento das doses de N em cobertura proporcionou aumento na produtividade de grãos nos três anos agrícolas da pesquisa, sendo que a cultura do milho após crotalária apresentou menor demanda de nitrogênio.

Cover Crop Selection by Jointly Optimizing Biomass Productivity, Biological Nitrogen Fixation, and Transpiration Efficiency: Application to Two Crotalaria Species

Crotalaria spectabilis and Crotalaria juncea are cover crops (CC) that are used in many different regions. Among the main attributes of these species are their high potential for biomass production and biological fixation of nitrogen (BNF). Attempting to maximize these attributes, while minimizing water consumption through high transpiration efficiency (TE), is a challenge in the design of sustainable agricultural rotations. In this study, the relationship between biomass productivity, BNF, and TE in C. spectabilis and C. juncea was evaluated. For this purpose, an experiment was carried out under controlled conditions without water limitations and using non-inoculated soil. BNF was determined by the natural abundance of 15N, while TE was estimated by several different methods, such as gravimetric or isotopic method (13C). C. juncea produced 42% less dry matter, fixed 28% less nitrogen from the air, and had 20% less TE than C. spectabilis. TE results in both species were consistent across methodologies. Under simulated environmental conditions of high temperature and non-limiting soil water content, C. spectabilis was a relatively more promising species than C. juncea to be used as CC.

Evapotranspiração e produtividade de milho safrinha consorciado com crotalária

Sistemas de consórcio vem como uma alternativa para redução da evaporação da água do solo e consequentemente maior disponibilidade de águas para as plantas. O objetivo deste trabalho foi verificar a influência do consórcio entre a cultura do milho com a crotalária, determinando a evapotranspiração das culturas e avaliando o efeito da competição hídrica nas características produtivas da cultura do milho. O experimento foi realizado no campo experimental da Universidade do Estado de Mato Grosso (UNEMAT), composto por três tratamentos, sendo: T1 - milho solteiro (Zea mays L.), T2 - crotalária solteira (Crotalaria juncea L.), e T3 - milho cultivado em consórcio com crotalária. A evapotranspiração de referência (ETo) foi estimada pela metodologia proposta por Penman-Monteith FAO-56. A evapotranspiração da cultura (ETc) dos tratamentos foram determinadas diariamente através da variação de massa de lisímetros de pesagem, convertida em mm dia-1. A evaporação do solo foi determinada com a utilização de microlisímetros. Foram determinadas as fases fenológicas das culturas para a determinação da ETc nos diferentes estádios de desenvolvimento conforme recomendado pela FAO-56, sendo: Inicial (I), Desenvolvimento (II), Intermediária (III) e Final (IV). Os componentes da produtividade do milho foram avaliados no final do ciclo da cultura. A evaporação do solo foi reduzida em 43,91 mm (26,78%), e a transpiração reduziu em 19,64 mm (14,85%) quando utilizado o sistema de milho consorciado, em relação ao milho em cultivo solteiro. A ETc acumulada foi de 312,00; 436,16 e 422,38 mm, para o milho, crotalária e o consórcio, respectivamente. A produtividade foi de 6739,26 e 4571,85 kg ha-1, para o milho em cultivo solteiro e consorciado, respectivamente.

Sunn Hemp : a Promising Cover Crop in Florida

SL-306 (formerly SS-AGR-96), a 4-page illustrated fact sheet by Yuncong Li, Qingren Wang, Waldemar Klassen, Edward A. Hanlon, Jr., describes this green manure crop that has been grown for centuries in Southeast Asia — origin and distribution, description, uses, production and harvest, and seed production. Includes references. Updated with title change by the UF Department of Soil and Water Sciences, September 2015. Minor revision October 2018.
 Previous version: 
 Li, Yuncong, Qingren Wang, Waldemar Klassen, and Edward Hanlon. 2009. “Sunn Hemp - A Cover Crop in Florida”. EDIS 2009 (8). https://journals.flvc.org/edis/article/view/118084.

Host suitability of cover crops for Meloidogyne javanica and M. incognita

Summary Management of plant-parasitic nematodes in no-tillage systems relies on knowledge of the species, their abundance and their host range in a certain cropping area. Crop rotation is one of the most efficient techniques in the control of plant-parasitic nematodes; thus, the identification of non-host plant species is essential. Therefore, the aim of this study was to evaluate the host suitability of different cover crops used in crop rotations to control two of the most devastating plant-parasitic nematodes in the Brazilian central region, Meloidogyne javanica and M. incognita. Two experiments were conducted in a completely randomised design under glasshouse conditions. In the M. incognita experiment, seven treatments (cover crops) were evaluated: Crotalaria juncea (sunn hemp; CJ), Stylosanthes humilis (Townsville stylo; TS), Pennisetum glaucum (millet; M), Triticum aestivum (wheat; W), Mucuna aterrima (black mucuna, BM), Glycine max (soybean treated with nematicide (fluensulfona) (SN) and soybean without nematicide (SwN)). In the M. javanica experiment, nine treatments were evaluated: Cajanus cajan (pigeon pea), Brassica napus (canola), B. nigra (mustard), CJ, M, W, BM, SN and SwN. The evaluations were performed 60 days after inoculation, when eggs and juveniles were present in the plant roots and soil, and the nematode reproduction factors (RF) were determined. The results indicated that CJ, M and BM were effective in controlling M. javanica and M. incognita. The SwN and even SN resulted in high RF and were not effective in the control of M. javanica and M. incognita.

Effect of Application of Crotalaria juncea L. Compost on Availability and Uptake of Ca, Mg, S by Sweet Corn (Zea mays saccharata Sturt) on an Entisol of Wajak, Malang

Entisol is a type of soil at the initial development stage and has a texture dominated by sand fraction. This causes a decrease in soil quality and can reduce crop production. This compost of leguminase plants can play a role in improving soil chemical properties. The purpose of this research was to determine the effect of Crotalaria juncea L. compost application on the availability of secondary macro nutrients Ca, Mg, and S, and uptake of Ca, Mg, and S by sweet corn plant in Entisol, Wajak. Treatments tested were C0 (Urea 100%), C1 (Compost Crotalaria juncea L. 100% + Urea 75%), C2 (Compost Crotalaria juncea L. 100% + Urea 75%), C3 (Compost Crotalaria juncea L. 100%), C4 (Compost Crotalaria juncea L. 200%). The five treatments were arranged in a completely randomized design with three replications. The results showed that the application of Crotalaria juncea L. compost (20 t ha -1 ) significantly increased the availability of Ca, Mg and S on 12 weeks by 41.6%, 96.71% and 133.78%, respectively. The application of Crotalaria juncea L. compost (20 t ha -1 ) did not significantly increase uptake of Ca, Mg and S.

Leguminous species effect in agroforestry systems in the Portuguesa state. Venezuela

Six leguminous species Frijol bayo (Vigna unguiculata), Frijol white Var. Orituco, Quinchoncho dwarf (Cajanus cajan (L.) Millsp., cv. Aroita), Kudzú tropical (Pueraria phaseoloides), Crotalaria (Crotalaria juncea), Sesbania (Sesbania grandiflora) were established in an agroforest systems to assess his effect on the chemical property of a Alfisol soil at municipality Ospino Portuguese state, at the farm La Yaguara planted with E. urograndis. In a design in random blocks with 7 processings and 4 repetitions, employing STATIXTIS 9.0 to carry out the ANDEVA and for variables where differences are presented the test was employed of Tukey (5%); obtaining as results that in the soil of the farm The Yaguara alone significant differences were found (P<0,05) for the variables relation C/N, CO, Zn, highly significant and differences (P<0,01)for N; being the Sesbania and quinchoncho the best treatment in relation C/N; for CO the frijol blanco and the treatment control; for Zn the quinchoncho and treatment control, frijol blanco and kudzú tropical; in the N quinchoncho and Sesbania. To confirm the generated profit to the agroforestry system analysis were completed foliate to the eucalyptus, finding highly significant differences for P with Frijol blanco and Kudzú and significant for Zn where is quinchoncho and treatment control.

Seleção de espécies tolerantes para a fitorremediação de solo contaminado com imazapic

O imazapic por apresentar longo efeito residual no solo pode ocasionar intoxicação visual em culturas sensíveis semeadas em rotação, além de representar riscos ecotoxicológicos em ambientes aquáticos. Diante disso, a fitorremediação é uma proposta inovadora como método alternativo para a remoção de poluentes orgânicos, sendo o sucesso da técnica dependente da seleção criteriosa de plantas com características favoráveis. O objetivo do estudo foi de identificar espécies de plantas tolerantes ao imazapic para potencial uso em programas de fitorremediação. Foram conduzidos oito experimentos em casa de vegetação climatizada com as espécies, Panicum maximum, Crotalaria juncea, Stylosanthes spp., Cajanus cajan, Dolichos lablab, Pennisetum glaucum, Mucuna aterrima, Raphanus sativus e cinco doses de imazapic (0; 58,33; 87,5; 175 e 350 g ha-1). Os tratamentos foram delineados em blocos ao acaso com quatro repetições. Aos 30 e 60 dias após a emergência das plantas foram avaliados os sintomas de intoxicação visual, altura e a massa seca das plantas, determinada ao término do experimento. As espécies M. aterrima, C. cajan e D. lablab não apresentaram sintomas visuais de fitointoxicação. M. aterrima foi a que promoveu maior produção de massa seca quando cultivada como testemunha e a exposição ao imazapic pouco afetou essa característica. Nas espécies tolerantes, a redução da altura e massa seca exigiu doses maiores, embora os resultados não tenham sido significativos para D. lablab e C. cajan. Entre essas espécies, M. aterrima se destacou pela alta produção de biomassa, sendo promissora na fitorremediação de sítios com resíduos do imazapic.

Sweet corn in no-tillage system on cover crop residues in the Brazilian Cerrado

In recent years, the growth of the cultivated area with sweet corn in conventional tillage system in Brazil expanded, although crops can be grown on different residues of cover crops, which improve nutrient cycling and crop productivity. The objective of this study was to evaluate the biomass production and to quantify the rate of plant residues decomposition of different cover crops, and correlate the results with the production and grain yield of sweet corn in an area located in the Cerrado biome. The experimental design used was randomized blocks with eight treatments: PM - pearl millet; SH - sunn hemp; SG - signal grass; PM + SH; PM + SG; SH + SG; PM+ SH + SG; FW - fallow (spontaneous vegetation), which preceded the cultivation of sweet corn. Fresh biomass (FB) and dry biomass (DB) of the cover crops were evaluated, as well as the rate of plant residue decomposition. Sweet corn productivity, straw and corncob weight, and grain yield were also determined. Pearl millet presented a better performance in FB production, decomposition rate, residue half-life (T½ life) in soil, yield, corn cob strawweight and yield of sweet corn. Pearl millet, when mixed with other plants, presented reduced rate of residue decomposition and increased residue T½ life. The FW presented the lowest biomass production, with great rate of decomposition and low T½ life. Cover crops grown before sweet corn in soils of good fertility did not affect crop agronomic characteristics. Pearl millet is the best cover crop adapted to Cerrado Brazilian climatic conditions to be used in monoculture or in mixtures with other plants.

<p><strong><em>Crotalaria shrirangiana </em></strong><strong>(Fabaceae): A new rattlepod from the Western Ghats of India</strong></p>

Crotalaria shrirangiana is described and illustrated as a new species in the present communication. The new species is found growing in northern Western Ghats ranges of Maharashtra. It is an erect, profusely branched under-shrub up to 1.5 m in height, with bright yellow flowers. It shows close affinities with Crotalaria juncea but is distinguished by details of its stem indumentum, shape and size of the leaves, inflorescence, bracts and bracteoles, shape and size of the flowers, standard petal, pod size and number of seeds per pod.

Cover Crops Management in the Soybean-Wheat Offseason

More than 2 million hectare of soil at the soybean-wheat offseason remains on fallow in Brazil. Therefore, this research studied a suitable cover crop and its herbicide management to be adopted is this period as well as its influence on wheat yield at the 2017/18 and 2018/19 growing season. Experiment was laid out as a randomized block design in a factorial scheme composed of four cover crops (Fagopyrum esculentum, Crotalaria juncea, Pennisetum glaucum and Urochloa brizantha) and two herbicide management [Anticipated Desiccation (17 days before) and Desiccation at the wheat Sowing day] with four replications. Fallow without cover crops was used as a control. The tradeoff between the additional biomass produced by millet and brachiaria between herbicide desiccation periods does not pay the wheat grain yield reduction, suggesting that its herbicide management should be anticipated. In the other hand, C. juncea showed a linear increase in biomass along the periods without wheat yield effects and its herbicide dissection at the wheat sowing day appears to be the best management. F. esculentum showed the fastest development cycle and can be recommended for shorter offseason periods. P. glaucum showed rapid growth and the highest biomass yield at both years, standing out as the best option for offseason periods from 70 to 80 days, although, anticipated herbicide management before wheat sowing resulted in higher grain yield at the second year of study. Further studies should consider other cover crop benefits as weed suppression, physical and chemical soil traits improvements and erosion reduction.

Arbuscular mycorrhizal fungi and soil aggregation in a no‐tillage system with crop rotation

AbstractCrop rotation adoption in no‐tillage systems (NTS) has been recommended to increase the biological activity and soil aggregation, suppress soil and plant pathogens, and increase the productivity aiming at the sustainability of agricultural areas. In this context, this study aimed to assess the effect of crop rotation on the arbuscular mycorrhizal fungi (AMF) community and soil aggregation in a soil cultivated for nine years under NTS. Treatments consisted of combinations of three summer crop sequences and seven winter crops. Summer crop sequences consisted of corn (Zea mays L.) monoculture, soybean (Glycine max L. Merrill) monoculture, and soybean–corn rotation. Winter crops consisted of corn, sorghum (Sorghum bicolor (L.) Moench), sunflower (Helianthus annuus L.), sunn hemp (Crotalaria juncea L.), pigeon pea (Cajanus cajan (L.) Millsp.), oilseed radish (Raphanus sativus L.), and millet (Pennisetum americanum (L.) Leeke). Soil samples were collected at a depth of 0–0.10 m for analyses of soil chemical, physical, and biological attributes. Spore abundance, total glomalin, and soil aggregate stability index were higher in the soil under corn monoculture. The highest values of aggregate mean weight diameter were observed in the soybean–corn rotation (3.78 mm) and corn monoculture (3.70 mm), both differing from soybean monoculture (3.15 mm), while winter crops showed significant differences only between sorghum (3.96 mm) and pigeon pea (3.25 mm). Two processes were identified in the soil under summer crop sequences. The first process was observed in PC1 (spore abundance, total glomalin, easily extractable glomalin, pH, P, and Mg2+) and was related to AMF; the second process occurred in PC2 (aggregate mean weight diameter, soil aggregate stability index, K+, and organic matter) and was related to soil aggregation. The nine‐year no‐tillage system under the same crop rotation adoption influenced AMF abundance in the soil, especially with corn cultivation in the summer crop sequence, which promoted an increased total external mycelium length and number of spores of AMF. In addition, it favored an increased soil organic matter content, which is directly related to the formation and stability of soil aggregates in these managements.

Plant Selection for the Establishment of Push-Pull Strategies for Zea mays-Spodoptera frugiperda Pathosystem in Morelos, Mexico.

Regulations imposed on the use of chemical insecticides call for the development of environmental-friendly pest management strategies. One of the most effective strategies is the push–pull system, which takes advantage of the behavioral response of the insect to the integration of repellent stimuli; it expels the pest out of the main crop (push), while attracting stimuli (attractants) pull the pest to an alternative crop or trap (pull). The objective of this study was to design a push–pull system to control Spodoptera frugiperda in maize crops (Zea mays) in Morelos, Mexico. Data on reproductive potential, larvae development, food consumption and olfactometry were used to obtain a Trap Plant Selection Index (TRAPS) based on Principal Component Analysis. This TRAPS was used to select the most suitable plants. The degree of repellency of potential plants to be used as the trap crop was studied with four-way olfactometers. S. frugiperda females oviposited more eggs on Brachiaria hybrid cv. Mulato II, Panicum maximum cv. Mombasa and Panicum maximum cv. Tanzania than on Z. mays, regardless of the fact that these plants delayed the development of their offspring. Dysphania ambrosioides, Tagetes erecta and Crotalaria juncea were less attractive to S. frugiperda females. Therefore, the former plants could be used as crop traps, and the latter as intercropped repellent plants in a push–pull system.

Behavioral response of Trichogramma papilionis to host eggs, host plants, and induced volatile plant cues

Egg parasitoids have evolved various searching behaviors to facilitate finding and locating their hosts in nature. Plant volatiles and host cues induced by egg deposition may be used by female wasps to detect host eggs. We studied host seeking behavior in Trichogramma papilionis (Hymenoptera: Trichogrammatidae) to different infochemical cues using Y-tube olfactometry. T. papilionis females preferred odors from Helicoverpa zea (Lepidoptera: Noctuidae) eggs compared to Ephestia kuehniella (Lepidoptera: Pyralidae) eggs. When plants were infested with H. zea eggs, T. papilionis preferred infested sunn hemp, Crotalaria juncea, over maize, Zea mays. No preference was observed in plants not infested with H. zea eggs, suggesting T. papilionis showed a positive response to stimuli from sunn hemp plants that might be induced by H. zea oviposition. The difference in plant volatile organic components with and without oviposition was investigated by head-space analysis. Compounds detected at notably higher concentrations in the egg plus plant material samples were found to be consistent with a number of compounds known to be pheromone-associated. Leaves with eggs oviposited on them produced some compounds that were unique compared to untreated plant material, and some of those compounds have known insect pheromone activity.

Reduction of Nitrogen Fertilizer Requirements and Nitrous Oxide Emissions Using Legume Cover Crops in a No-Tillage Sorghum Production System

Nitrous oxide (N2O) emission from denitrification in agricultural soils often increases with nitrogen (N) fertilizer and soil nitrate (NO3−) concentrations. Our hypothesis is that legume cover crops can improve efficiency of N fertilizer and can decrease N2O emissions compared to non–cover crop systems. The objectives of this study were to (a) evaluate the performance of summer leguminous cover crops in terms of N uptake and carbon (C) accumulation following winter wheat and (b) to quantify the effects of summer leguminous cover crops and N fertilizer rates on N2O emissions and grain yield of the subsequent grain sorghum crop. Field experiments were conducted in the context of a wheat-sorghum rotation for two seasons in Kansas. Treatments consisted of double-cropped leguminous cover crops following winter wheat harvest with no fertilizer applied to the following grain sorghum or no cover crop after wheat harvest and N fertilizer rates applied to the grain sorghum. The cover crops were cowpea (Vigna unguiculata L. Walp.), pigeon pea (Cajanus cajan L. Millsp.), and sunn hemp (Crotalaria juncea L.). The three N treatments (were 0, 90, and 180 kg·N·ha−1). Fallow systems with 90 and 180 kg·N·ha−1 produced significantly greater N2O emissions compared with cropping systems that received no N fertilizer. Emissions of N2O were similar for various cover crops and fallow systems with 0 kg·N·ha−1. Among cover crops, pigeon pea and cowpea had greater C accumulation and N uptake than sunn hemp. Grain yield of sorghum following different cover crops was similar and significantly higher than fallow systems with 0 kg·N·ha−1. Although fallow systems with 90 and 180 kg·N·ha−1 produced maximum sorghum grain yields, N2O emissions per unit of grain yield decreased as the amount of N fertilizer was reduced. We conclude that including leguminous cover crops can decrease N fertilizer requirements for a subsequent sorghum crop, potentially reducing N2O emissions per unit grain yield and providing options for adaptation to and mitigation of climate change.

Nitrogen recovery from fertilizers and cover crops by maize crop under no-tillage system

Crop rotation associated with the use of cover crops promotes the introduction of crop residues to the soil, with direct and indirect effects on the availability of plant nutrients, especially nitrogen (N). The objectives of this study were to estimate the N utilization from 15N-urea and cover crop residues (labelled with 15N) of maize crops grown in succession, and evaluate the effects of the isolated and combined use of cover crops and urea on maize plant height, yield components, and grain yield, grown under a no-tillage system. Field research was conducted in an Oxisol (Rhodic Haplustox), Cerrado (Savannah) phase. The experimental design was a randomized block with 20 treatments and four replications in a 5x4 factorial scheme. The treatments were four cover crops species: sunn hemp (Crotalaria juncea L.), pigeon pea (Cajanus cajan (L.) Millsp), green velvet bean (Mucuna prurens), and millet (Pennisetum glaucum L.) + spontaneous vegetation (fallow in the off-season), combined with four N rates: 0, 30, 90, and 150 kg ha-1, applied at the sowing and topdressing stages. The results showed that legume cover crops provided maize grain yields equivalent to the application of 80-108 kg ha-1 N as urea. The urea N utilization by the maize was at an average of 43.5 % of the applied amount. The results indicate that cover crops, particularly legume cover crops, are an important source of N to non-legume cereals. Legumes used as cover crops can replace nitrogen fertilizers of more than 80 kg ha, which is both environmentally and economically viable for corn production.

Legume Cover Crop Effects on Temperate Sugarcane Yields and Their Decomposition in Soil

Sugarcane is commercially produced on 340,000 ha in the US and is valued at over $1 billion US annually. Cultural practices that improve sugarcane sustainability are needed to maintain yields in fields with degraded soils. Historically, leguminous rotation crops provided organic matter and biologically fixed nitrogen (N) for subsequent sugarcane crops. Currently, sugarcane is usually grown as a monoculture with only a short, 6-month fallow period. The objective of these field studies was to determine how growing cowpea (Vigna unguiculata (L.) Walp.) and sunn hemp (Crotalaria juncea L.) as cover crops during fallow affected the yield of subsequent sugarcane crops. A companion laboratory study investigated the decomposition rate of cover crops in soil at different temperatures. Cowpea and sunn hemp production produced 12.8 t/ha dry matter and 250 kg N/ha. Cowpea generally improved plant cane yields, but the effects of sunn hemp varied. However, neither cowpea nor sunn hemp reduced cane or sucrose yields consistently, and mineral N additions may have a role in mitigating yield gains or losses. Based on laboratory data, the average half-life for cowpea and sunn hemp would be 3 months. Overall, using legume cover crops should be viewed as an important component of sustainable sugarcane practices.

Farklı Azot Dozlarının Krotalarya (Crotalaria juncea L.)’da Verim ve Diğer Bazı Verim Özellikleri Üzerine Etkisi

Bu araştırma, farklı azot dozlarının (0, 3, 6, 9, 12, 15 kg/da) Krotalarya (Crotalaria juncea L.) bitkisinde verim ve bazı verim özellikleri üzerine olan etkisini incelemek amacıyla 2018 yılında Ege Üniversitesi Ziraat Fakültesi Tarla Bitkileri Bölümü’nün Bornova/İzmir’deki deneme alanlarında yürütülmüştür. Araştırmada; bitki materyali olarak yurtdışından temin edilen Tillage Sunn çeşidi kullanılmış ve bitki boyu, sap çapı, dal sayısı, yaprak sayısı, yeşil ve kuru ot verimi, kuru madde oranı ve kuru madde verimi gibi özellikler incelenmiştir. Elde edilen verilere göre; 12 kg/da azot uygulamasında 5221 kg/da ile en yüksek yeşil ot verimi, 1553 kg/da ile en yüksek kuru ot verimi, 216,4 cm ile en yüksek bitki boyu, 13,67 mm ile en yüksek sap çapı, 5,73 adet ile en fazla dal sayısı, 167,9 adet ile en fazla yaprak sayısı elde edilmiş ve Krotalarya yetiştiriciliğinde optimum miktarda azot uygulamasının gerekli olduğu ve Akdeniz iklim koşulları altındaki Bornova ovasında en ideal azot dozunun 12 kg/da olduğu sonucuna varılmıştır.

Scope for non-crop plants to promote conservation biological control of crop pests and serve as sources of botanical insecticides

Besides providing food and shelter to natural enemies of crop pests, plants used in conservation biological control interventions potentially provide additional ecosystem services including providing botanical insecticides. Here we concurrently tested the strength of these two services from six non-crop plants in managing cabbage pests in Ghana over three successive field seasons. Crop margin plantings of Ageratum conyzoides, Tridax procumbens, Crotalaria juncea, Cymbopogon citratus, Lantana camara and Talinum triangulare were compared with a bare earth control in a three-way split plot design such that the crop in each plot was sprayed with either a 10% (w/v) aqueous extract from the border plant species, a negative control (water) and a positive control (emamectin benzoate ‘Attack’ insecticide). Pests were significantly less numerous in all unsprayed treatments with non-crop plant margins and in corresponding sprayed treatments (with botanical or synthetic insecticide positive control) while treatments with bare earth margin or sprayed with water (negative controls) had the highest pest densities. Numbers of predators were significantly depressed by synthetic insecticide but higher in other treatments whether unsprayed or sprayed with botanical insecticide. We conclude that some plant species have utility in both conservation biological control and as source of botanical insecticides that are relatively benign to natural enemies. In this crop system, however, the additional cost associated with using botanical insecticides was not justified by greater levels of pest suppression than achieved from border plants alone.

Residues of sweet sorghum promotes suppression of weeds in sugarcane rotation

Sorghum is an important crop to plant in rotation with sugarcane. This is mainly because both are inputs for the ethanol industry. Crop residues of sweet sorghum promote suppression of weed re-infestation, avoiding weed interference to the sugarcane crop due to the strong allelopathic potential of sorghum. In order to determine the suppressive effects of sorghum crop residues on weeds, a field experiment was carried out. Seven vegetation covers were used as options for crop rotation with sugarcane. The treatments were sweet sorghum, velvet bean, sunflower, soybean, sugar cane, fallow, and an area without cover. The experiment was randomized blocks with four replications of 27 m2 plots. The weed community of each plot was evaluated by phytosociological indexes at 60 and 120 days after the formation of vegetation cover. The composition of soil seed bank was also evaluated. The weeds with the highest indexes of relative importance during the evaluations were Cyperus rotundus, Raphanus raphanistrum and Parthenium hysterophorus. The diversity of the weed community, estimated by relative importance indexes, was lower in the area with velvet bean as soil cover. Sorghum, velvet bean and sunn hemp covers reduced the soil seed bank compared to the fallow treatment and the treatment without vegetation cover. Crop residues of sweet sorghum and velvet bean provide a decrease in weed infestation in field, and the weed suppression period can last up to 120 days during the dry season.