Mossoró, RN, Brazil, is considered one of the fruit growing centers of the Northeast region. This municipality has a persistent water deficit, with the need to develop irrigated agriculture with efficient water use and rational management of irrigation. The objective of this study was to evaluate estimation methods of reference evapotranspiration (ETo) for different climate conditions of Mossoró, comparing them with the standard Penman-Monteith-FAO 56 method. A daily data series of two distinct years, a rainy (2011) and a dry year (2012), was used. The data were obtained from the weather station of the Federal Rural University of the Semi-Arid Region (UFERSA). An analysis was performed to identify methods that best fit those of Penman-Monteith-FAO 56, and for this, ten methods were evaluated using statistical indices. The Penman-Original, Radiation-Temperature, and Hargreaves-Original methods stood out and satisfactorily met ETo estimation for the rainy season, while the Jensen-Haise, Radiation-Temperature, and Hargreaves-Original methods achieved satisfactory performance for the dry season. The Hargreaves-Samani method did not demonstrate viability in the use of ETo estimation, as it was the worst method in both studied periods and is not recommended for irrigation management.

-Brazil is one of the world's largest producers of melon (Cucumis melo L.), and Rio Grande do Norte and Ceará are the largest producers states of the country (99% of exports). This crop had great socioeconomic importance in the Brazilian Northeast, however, it is affected by insect pests and consequently, large amounts of pesticides are applied to it, which greatly affect beneficial organisms, such as Chrysopidae. This bioassay evaluated the toxicity of nine insecticides used in commercial crops of muskmelon, applied to firstinstar larvae of Chrysoperla genanigra of up to 24-hour-old, from mass rearing cultures. Sublethal effects were evaluated, classifying the insecticides into the toxicity classes recommended by the IOBC. A completely randomized design was used, consisting of ten treatments (clothianidin, pymetrozine, lambda-cyhalothrin, chlorantraniliprole, indoxacarb, pyriproxyfen, beta-cyfluthrin+imidacloprid, imidacloprid, beta-cypermethrin and a control consisted of distilled water). The treatments consisted of exposure of thirty larvae to dry residues of each product in Petri dishes, assessing their mortality, duration of instars, sex ratio, fecundity and viability of eggs from adults of the insects evaluated. The products were classified in toxicity classes as harmful (Class 4) (clothianidin, pymetrozine, indoxacarb, lambda-cyhalothrin, beta-cyfluthrin+imidacloprid, imidacloprid, betacypermethrin and pyriproxyfen) and innocuous (Class 1) (chlorantraniliprole) to first-instar larvae of C. genanigra, by calculate their total effect. Based on this work, chlorantraniliprole is the only recommended insecticide for use in integrated pest management (IPM) programs in muskmelon crops.Keywords: Green lacewings. Predator. Cucurbitaceae, MIP. TOXICIDADE DE INSETICIDAS UTILIZADOS NO MELOEIRO SOBRE PRIMEIRO INSTAR DEChrysoperla genanigra FREITAS (NEUROPTERA: CHRYSOPIDAE) RESUMO -O Brasil é um dos maiores produtores de melão (Cucumis melo L.), tendo os estados do Rio Grande do Norte e Ceará os maiores representantes (99% das exportações), com enorme relevância do ponto de vista socioeconômico para a região nordeste. No entanto, a cultura é acometida por insetos-praga, razão pela qual grandes quantidades de agrotóxicos são necessárias os quais afetam sobremaneira organismos benéficos como os crisopídeos. O bioensaio avaliou a toxicidade de nove inseticidas utilizados comercialmente na cultura do meloeiro, aplicados sobre primeiro instar larval de Chrysoperla genanigra, avaliando, inclusive, efeitos subletais, categorizando os inseticidas em classes de toxicidade preconizadas pela IOBC. Foram utilizadas larvas com até 24h de idade, oriundas de criação massal. Utilizou-se o delineamento inteiramente casualizado, composto por dez tratamentos: clotianidina, pimetrozina, lambda-cialotrina, clorantraniliprole, indoxacarbe, piriproxifem, beta-ciflutrina + imidaclopride, imidaclopride, beta-cipermetrina e a testemunha constituída de água destilada. Cada tratamento consistiu na exposição de trinta larvas aos resíduos ...

RESPOSTA DO ALGODOEIRO À SUPRESSÃO HÍDRICA EM DIFERENTES FASES FENOLÓGICAS NO SEMIÁRIDO BRASILEIRO     RUDAH MARQUES MANIÇOBA1; JOSÉ ESPÍNOLA SOBRINHO 2; JOÃO HENRIQUE ZONTA3; EDMILSON GOMES CAVALCANTE JUNIOR4; ANNA KÉZIA SOARES DE OLIVEIRA5 E ISAAC ALVES DA SILVA FREITAS6   1 Universidade Federal Rural do Semi-Árido, UFERSA, Avenida Francisco Mota, 572, Bairro Costa e Silva, RN, Brasil. E-mail: rudahmanicoba@gmail.com 2 Centro de Engenharias, Universidade Federal Rural do Semiárido,  UFERSA, Avenida Francisco Mota, 572, Bairro Costa e Silva,  Mossoró,  RN, Brasil. E-mail: jespinola@ufersa.edu.br 3 Embrapa Algodão, Rua Oswaldo Cruz, 1143, Bairro Centenário, Campina Grande, PB, Brasil, E-mail: joao-henrique.zonta@embrapa.br 4 Unidade Acadêmica de Engenharia Civil, Universidade Federal de Campina Grande, UFCG, Rua Aprígio Veloso, 882 -Universitário, Campina Grande, PB, Brasil. E-mail: edmilson.gomes@ufcg.edu.br 5 Universidade Federal Rural do Semi-Árido, UFERSA, Avenida Francisco Mota, 572, Bairro Costa e Silva, RN, Brasil. E-mail: annakezia@outlook.com 6 Universidade Federal Rural do Semi-Árido, UFERSA, Avenida Francisco Mota, 572, Bairro Costa e Silva, RN, Brasil. E-mail: isaacntn@outlook.com     1 RESUMO   O Semiárido do Nordeste brasileiro tem como característica climática a irregularidade temporal e espacial do seu regime de chuvas. Portanto, objetivou-se com o presente trabalho avaliar o efeito da supressão hídrica, aplicada em diferentes fases fenológicas, sobre os componentes de produção de cultivares de algodoeiro herbáceo. O trabalho foi realizado na cidade de Apodi-RN. O delineamento experimental adotado foi em blocos casualizados em parcelas subdivididas e com quatro repetições. Os tratamentos consistiram de quatro períodos de supressão hídrica nos seguintes estágios fenológicos: primeiros botões florais, início do florescimento, pico do florescimento e abertura dos capulhos, além do tratamento controle (sem supressão hídrica) e quatro cultivares de algodoeiro herbáceo: BRS 368 RF, BRS 336, BRS 432 B2RF e BRS 430 B2RF. A supressão hídrica durante as fases de início da abertura das flores e no pico do florescimento foram as mais prejudiciais e as cultivares BRS 432 B2RF e BRS 368RF apresentaram os melhores resultados. Nas condições desse estudo, a irrigação até 90 dias após a emergência foi suficiente para conseguir altas produtividades. Dessa forma, a decisão em irrigar o algodoeiro com ou sem supressão hídrica é válida, e dependerá dos custos da irrigação e do valor de mercado do produto.   Palavras-chave: manejo de irrigação, Gossypium hirsutum L. r. latifolium H., estresse hídrico, produtividade.     MANIÇOBA, R. M; ESPÍNOLA SOBRINHO, J.; ZONTA, J. H.; CAVALCANTE JUNIOR, E. G.; OLIVEIRA, A. K. S. de; FREITAS, I. A. da S. COTTON RESPONSE TO WATER STRESS AT DIFFERENT PHENOLOGICAL STAGES IN THE BRAZILIAN SEMIARID     2 ABSTRACT   The semiarid of Brazilian northeast has as its climatic characteristic the temporal and spatial irregularity of its rainfall regime. Thus, this work aimed to evaluate the effect of water suppression, applied at different phenological stages, in the production components of herbaceous cotton cultivars. The study was conducted in the city of Apodi-RN. The experimental design was randomized blocks in a split-plot design with four replications. The treatments consist of four periods od water suppression in the following phenological stages: the first square, first flower, peak bloom, and first open boll, besides the control treatment (without water suppression), and four herbaceous cotton cultivars: BRS 368 RF, BRS 336, BRS 432 B2RF and BRS 430 B2RF. Water suppression causes greater losses in cotton yield during the first flower and peak bloom phenological stages, because of the high water demand in these phases. The cultivars BRS 432 B2RF and BRS 368RF had higher yield components. Under this study conditions, irrigation up to 90 days after emergence was sufficient to achieve high yields. Therefore, the decision to irrigate cotton with or without water suppression is valid, and will depend on the costs of irrigation and the market value of the product.   Keywords: irrigation management, Gossypium hirsutum L. r. latifolium H, water stress, productivity.

The large variation in the response of sunflower to nitrogen fertilization indicates the need for studies to better adjust the optimum levels of this nutrient for production conditions. Our objectives were to analyze the agronomic yield of sunflower cultivars as a function of nitrogen fertilization; indicate the cultivar with high nitrogen use efficiency; and measure the adequate N dose for sunflower through nutritional efficiency. The completely randomized block design with split plots was used to conduct the experiments. The treatments included five nitrogen rates being allocated in the plots and the four sunflower cultivars. To estimate the nutrient use efficiency in the sunflower, we measured agronomic efficiency (AE), physiological efficiency (PE), agrophysiological efficiency (APE), apparent recovery efficiency (ARE), and utilization efficiency (UE). The results indicate that all cultivars had a reduction in AE due to the increase in N doses in the first crop. For PE, the highest values were observed for Altis 99 during the 2016 harvest. In that same harvest, Altis 99 had the highest APE. The dose of 30 kg ha−1 provided greater ARE for all cultivars in both crops, with greater emphasis on BRS 122 and Altis 99. The cultivation of cultivars Altis 99 and Multissol at a dose of 30 kg ha−1 in is recommended semiarid regions.

The determination of leaf area is fundamental for studies related to plant growth and physiology. Thus, non-destructive methods allow an accurate estimate of the leaf area through linear dimensions of the leaves. The research objective was to construct allometric equations to estimate the leaflet area of peanut cultivars. Then, 2,605 leaflets were collected from six peanut cultivars (IAC Caiapó, IAC 8112, Runner IAC 886, BRS Havana, BRS 151 L7, and IAC Tatuí), with more than 400 leaflets sampled for each cultivar. We measured the length, width, product between length and width, and leaflet area. Linear and non-linear models (linear, linear without intercept, power, and exponential) were built, and the best equation was chosen using the statistical criteria: highest coefficient of determination (R 2 ), Pearson's linear correlation coefficient (r), Willmott's agreement index (d), lowest Akaike information criterion (AIC), and root mean square of the error (RMSE). It was found that the models that used the product between length and width were the most suitable for estimating the leaflet area of peanut cultivars. Given the little intraspecific morphological variability, it was possible to group the cultivars, and model ̂= 0.875 * LW 0.929 was indicated to estimate the peanut leaflet area accurately, regardless of the cultivar.