Evaluation, Characterization, and Utilization of Weed-Suppressive Sweetpotato Cultivars for Sustainable Weed Management

Sweetpotato (Ipomoea batatas L.) is a low-technology, subsistence crop that enhances food and nutrition security particularly in developing nations. Weed interference with the crop can reduce sweetpotato storage root yields and product quality. Current weed management practices in sweetpotato include PRE or POST herbicides application, cultivation, mowing, or handweeding. Unlike row crops, herbicide options for sweetpotato are few; therefore, alternative weed control practices are needed. The overall objective of this research was to determine the weed suppressive ability of several sweetpotato cultivars. This research also provides information about cover crop use for weed suppression in sweetpotato production in Arkansas. Field experiments were conducted in Fayetteville and Kibler to assess the weed suppressive ability with or without full-season interference of broadleaf spp., grass spp., or sedges spp.. Data collected included leaf area index (LAI), vine length, canopy height, weed biomass, and sweetpotato yield by grade. Four sweetpotato cultivars were selected from this study and integrated with winter cover crops in a second set of field experiments conducted in Kibler and Augusta, AR. A mixed combination of cereal rye (Secale cereale L.) + crimson clover (Trifolium incarnatum L.), and winter wheat (Triticum aestivum L.) + crimson clover was compared to a fallow ground control. Data collected were vine length, canopy height, weed biomass, cover crop biomass, and sweetpotato yield by grade. ‘Heartogold’, ‘Centennial’, and ‘Stokes Purple’ were found to have allelopathic activity in greenhouse setting. These results were confirmed in the field experiments. ‘Heartogold’ was strongly weed suppressive for both grass spp. and broadleaf spp., and yellow nutsedge (Cyperus esculentus L.). ‘Hatteras’ and ‘Centennial’ significantly reduced yellow nutsedge growth. These three cultivars have short vines and upright growth. Cultivars with long vines were generally less competitive with weeds. Canopy height and LAI were not correlated with weed suppression, indicating the contribution of another factor toward weed suppression. The most weed-suppressive cultivars were not always the highest yielding. ‘Beauregard-14’ and ‘Bayou Belle-6’ performed better in fields with broadleaf or grass weeds. ‘Bayou Belle-2’, ‘Bayou Belle-6’, ‘Hatteras’, and ‘Centennial’ yielded more in fields infested with yellow nutsedge. Vine length and LAI were positively correlated with jumbo, no.1, and total sweetpotato yield. A mix of cereal rye + clover is a suitable choice for a reduced-till, organic sweetpotato system. This cover crop mixture provided a higher weed suppression compared to that of winter wheat + crimson clover and resulted in numerically higher sweetpotato yields. Altogether, this research showed that there are commercially acceptable, weed-suppressive sweetpotato cultivars and these types of cultivars should be utilized to breed cultivars for commercial production. Weed-suppressive cultivars should be used as a tool for integrated weed management to reduce weed infestation levels, which leads to better performance of herbicides in conventional production and reduced handweeding cost in either conventional or organic sweetpotato production. Furthermore, planting weed-suppressive cultivars will complement the efficacy of cover crops in reducing early-season weed infestation, providing extended weed suppression after the activity of allelochemicals from the cover crop had dissipated and the sweetpotato has established

Estudo do efeito ansiolítico e antidepressivo da vitamina D em camundongos

TCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências da Saúde. Farmácia.A depressão e ansiedade são transtornos psiquiátricos que acometem milhões de pessoas no mundo, acarretando sintomas negativos que reduzem a qualidade de vida dos indivíduos afetados. A etiologia destes transtornos ainda não está totalmente elucidada, mas evidências crescentes suportam que há envolvimento do sistema serotonérgico. Existe um amplo arsenal terapêutico para tratamento destes transtornos e muitos dos fármacos atuam sobre o sistema serotonérgico, porém, a demora na remissão dos sintomas e os efeitos adversos consideráveis causados por estes fármacos diminuem a adesão dos pacientes ao tratamento. Assim, a busca por compostos com atividade antidepressiva/ansiolítica e o desenvolvimento de novas terapias clinicamente eficazes é de extrema importância. Neste contexto, a vitamina D tem se mostrado promissora, parecendo possuir atividades relacionadas a melhora nos quadros de depressão e ansiedade, porém, ainda existem poucos estudos explorando esta vitamina. Através do presente trabalho, pretende-se caracterizar os efeitos ansiolíticos e antidepressivos da vitamina D3, além de investigar a participação do sistema serotonérgico nestes efeitos. Aqui, observamos efeito tipo-antidepressivo no teste de suspensão pela cauda decorrente do tratamento repetido por 7 dias com vitamina D (100 UI/Kg) por via oral em camundongos Swiss fêmeas. Ainda, fornecemos evidência de que este efeito envolve o sistema serotonérgico, uma vez que o tratamento dos camundongos com o inibidor da síntese de serotonina pclorofenilalanina metil éster (PCPA; 100 mg/Kg por 4 dias) aboliu o efeito do tipoantidepressivo da vitamina D (100 UI/Kg). Por outro lado, o tratamento com diferentes doses desta vitamina (100 UI/Kg, 300 UI/Kg e 1000 UI/Kg, p.o., por 7 dias) não produziu efeito tipoansiolítico nos camundongos submetidos ao teste do labirinto em cruz elevado. Estudos futuros serão necessários para melhor compreender o efeito da vitamina D nestes transtornos psiquiátricos.Depression and anxiety are psychiatric disorders that affect millions of people around the world, causing negative symptoms that reduce the quality of life of those affected. The etiology of these disorders is not yet fully elucidated, but growing evidence supports the involvement of the serotonergic system. There is a broad therapeutic arsenal for the treatment of these disorders and many of the drugs act on the serotonergic system, but the delay in the remission of symptoms and the considerable adverse effects caused by these drugs decrease the adherence of patients to treatment. Thus, the search for compounds with antidepressant/anxiety activity and the development of new clinically effective therapies is of extreme importance. In this context, Vitamin D has shown to be a promising compound, since it has activities related to the improvement of depression and anxiety, but there are still few studies exploring this nutraceutical. In this study we aim to characterize the anxiolytic and antidepressant effects of Vitamin D3, in addition to investigate the participation of the serotonergic system in these effects. In the present study, we observed an antidepressant-like effect in the tail-suspension test following repeated 7-day treatment with oral Vitamin D (100 IU/Kg) in female Swiss mice. We further provide evidence that this effect involves the serotonergic system, since treatment of the mice with the serotonin synthesis inhibitor p-chlorophenylalanine methyl ester (PCPA; 100 mg/Kg for 4 days) abolished the antidepressant-like effect of vitamin D (100 IU/Kg). On the other hand, treatment with different doses of this vitamin (100 UI/Kg, 300 UI/Kg and 1000 UI/Kg, p.o., for 7 days) did not produce an anxiolytic-like effect in mice subjected to the elevated plus-maze test. Future studies will be needed to better understand the effect of Vitamin D on these psychiatric disorders

Ocorrência de brusone e qualidade de grãos em arroz irrigado adubado com nitrogênio e silicatos

The objective of this work was to evaluate the effects of fertilization with nitrogen topdressing and silicates, as well as of the use of fungicides, on the occurrence of panicle blast, milling yield, and whole grains, vitreous grains, and chalky kernels in an irrigated rice cultivar sensitive to the disease. Two experiments were conducted in a randomized complete block design, in a 4×4×2 factorial arrangement, with four replicates: in experiment 1, four doses of nitrogen × four doses of calcium and magnesium silicate on soil × with and without fungicides; and, in experiment 2, four doses of nitrogen × four doses of potassium silicate applied on leaves x with and without fungicides. At the doses above 60 kg ha-1 nitrogen without fungicides, there was an increase in panicle blast severity, a decrease in the percentage of whole and vitreous grains, and an increase in chalky kernels and chalky area. The greatest effects of silicates occurred without fungicides. Fungicide use reduced the severity of blast in the panicles. Milling yield ranged from 60 to 70% in both experiments. The control of blast with fungicides maintains high rice grain quality, milling yield, and percentages of whole and vitreous grains.O objetivo deste trabalho foi avaliar os efeitos da adubação com nitrogênio em cobertura e silicatos, bem como da utilização de fungicidas, sobre a ocorrência de brusone nas panículas, a renda do benefício e os grãos inteiros, vítreos e gessados, em cultivar de arroz irrigado sensível à doença. Foram conduzidos dois experimentos em delineamento de blocos ao acaso, em arranjo fatorial 4×4×2, com quatro repetições: no experimento 1, quatro doses de nitrogênio × quatro doses de silicato de cálcio e magnésio via solo × com e sem uso de fungicidas; e, no experimento 2, quatro doses de nitrogênio × quatro doses de silicato de potássio via foliar × com e sem fungicidas. Nas doses acima de 60 kg ha-1 de nitrogênio sem fungicidas, houve aumento da severidade de brusone nas panículas, redução do percentual de grãos inteiros e vítreos, e aumento de grãos gessados e área gessada. Os maiores efeitos dos silicatos ocorreram sem aplicações de fungicidas. O uso de fungicidas reduziu a severidade de brusone nas panículas. A renda do benefício oscilou entre 60 e 70%, em ambos os experimentos. O controle da brusone com fungicidas mantém elevadas a qualidade de grãos do arroz, a renda do benefício e as percentagens de grãos inteiros e vítreos

Identification of Weed-Suppressive Tomato Cultivars for Weed Management

Weed-suppressive crop cultivars are a potentially attractive option in weed management strategies (IWM). A greenhouse study was conducted at the R. R. Foil Plant Science Research Center, Starkville, MS, to assess the potential weed-suppressive ability of 17 tomato cultivars against Palmer amaranth (Amaranthus palmeri S. Wats), yellow nutsedge (Cyperus esculentus L.), and large crabgrass (Digitaria sanguinalis L.). The experiment was a completely randomized design, with four replications, and was repeated twice. The height, chlorophyll, and dry weight biomass of the weeds were measured 28 days after sowing. Weed suppression varied greatly among tomato cultivars. The most significant effect of tomato interference was recorded on Palmer amaranth, and the least reduction was observed with yellow nutsedge plants. Cultivars 15 and 41 reduced Palmer amaranth height and biomass by about 45 and 80%, respectively, while cultivar 38 reduced 60% of the chlorophyll percentage. Large crabgrass plants were 35% shorter in the presence of cultivar 38 and had a biomass reduction of 35% in the presence of cultivar 38. Under tomato interference, a minimal effect was observed in chlorophyll, height, and biomass of yellow nutsedge seedlings. Factoring all parameters evaluated, cultivars 38 and 33 were most suppressive against Palmer amaranth and large crabgrass

Weed phytosociological in irrigated rice under different cultivation systems and crop rotation intensity

ABSTRACT: This research aimed to evaluate the phytosociology of weeds in irrigated rice in different soil management systems and crop rotation intensity. Therefore, two field studies were carried out. Study 1 was conducted in an area that has been cultivated since 1994 with three cultivation systems: direct, pre-germinated and conventional ones. Study 2 was carried out in an experimental area in five Integrated Farming Systems, with crop rotation. Phytosociological evaluations were conducted when rice was fully blooming, in the first study, and when grain filling was ending, in the second study. Pre-germinated system of rice cultivation has predominance of aquatic weeds. Conventional system when compared with direct sowing has lower weed densities. Integrated Agricultural Production Systems with higher intensity of crop rotation have been higher infested of perennial species

High Resistance to Quinclorac in Multiple-Resistant <i>Echinochloa colona</i> Associated with Elevated Stress Tolerance Gene Expression and Enriched Xenobiotic Detoxification Pathway

Echinochloa colona and other species in this genus are a threat to global rice production and food security. Quinclorac, an auxin mimic, is a common herbicide for grass weed control in rice, and Echinochloa spp. have evolved resistance to it. The complete mode of quinclorac action and subsequent evolution of resistance is not fully understood. We analyzed the de novo transcriptome of multiple-herbicide-resistant (ECO-R) and herbicide-susceptible genotypes in response to quinclorac. Several biological processes were constitutively upregulated in ECO-R, including carbon metabolism, photosynthesis, and ureide metabolism, indicating improved metabolic efficiency. The transcriptional change in ECO-R following quinclorac treatment indicates an efficient response, with upregulation of trehalose biosynthesis, which is also known for abiotic stress mitigation. Detoxification-related genes were induced in ECO-R, mainly the UDP-glycosyltransferase (UGT) family, most likely enhancing quinclorac metabolism. The transcriptome data also revealed that many antioxidant defense elements were uniquely elevated in ECO-R to protect against the auxin-mediated oxidative stress. We propose that upon quinclorac treatment, ECO-R detoxifies quinclorac utilizing UGT genes, which modify quinclorac using the sufficient supply of UDP-glucose from the elevated trehalose pathway. Thus, we present the first report of upregulation of trehalose synthesis and its association with the herbicide detoxification pathway as an adaptive mechanism to herbicide stress in Echinochloa, resulting in high resistance