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Cultivos protegidos são alternativas diante da sazonalidade e adversidades climáticas. Estudos que avaliem diferentes ambientes de cultivo são importantes para compreender os processos adaptativos das espécies. O trabalho teve como objetivo determinar variações na radiação solar e na temperatura do ar ocasionadas pelo uso de cobertura plástica em cultivo de videira ‘Niágara rosada’. O experimento foi realizado numa propriedade familiar, por duas safras, em um ambiente com cobertura plástica impermeável e em outro ambiente sem cobertura, cultivados com videira no sistema de condução latada. Na safra 2014/15, com baixa nebulosidade, a radiação solar global média foi de 22,4 MJ m-2 dia-1, no ambiente sem cobertura, e de 14,4 MJ m-2 dia-1, no ambiente com cobertura plástica. Na safra 2015/16, com grande nebulosidade, a radiação solar global foi de 12,9 e de 8,9 MJ m-2 dia-1, nos ambientes sem e com cobertura plástica, respectivamente. As temperaturas mínimas do ar não foram afetadas pela cobertura plástica e as temperaturas médias e máximas foram maiores no ambiente coberto. Acima do dossel, as temperaturas médias do ar foram acrescidas em mais de 2,0 °C e as temperaturas máximas em mais de 8,6 °C. Palavras-chave: Microclima; plasticultura; uva de mesa; elementos meteorológicos.

Grafting can be an ally in the vegetable’s soilless cultivation, being the objective of this work evaluate the growth and production, as well as to define the thermal sum and trophic limit of grafted and non-grafted tomato plants cultivated in substrate. The experiments were conducted in a protected environment in the city of Jaguari-RS, in two growing seasons in the years 2019 and 2020. Italian and Gaucho tomato cultivars were used, the rootstock was chosen for giving vigor and longevity to the plants. Yield data were obtained through weekly fruit harvesting, growth data through periodic collections of whole plants and the total biomass obtained at the end of the experiments. Grafted plants show greater vegetative growth regardless of the crop season; however, non-grafted plants are more productive in a growing cycle with restricted light and low temperatures. Grafted plants require a greater thermal sum to complete their phenological stages. The trophic limit for grafted and non-grafted plants of Italian and Gaucho tomato cultivars is 4.8 MJ/m2/day.

The occurrence of water deficit is intensified in lowland soils. Generating information with regard to its risk of occurrence is essential to avoid seed yield losses. The objective of this study was to determine the probability of water deficit in soybean cultivated in lowlands of the Vacacaí and Piratini River basins in the southern portion of Rio Grande do Sul in Brazil as a function of the sowing date. Soybean development was simulated considering three sets of cultivars of relative maturity groups (RMG) delimited by 5.9–6.8, 6.9–7.3, and 7.4–8.0, with a 10-day interval between the sowing dates making up the period between 21 September and 31 December. Daily meteorological data were used from 1971 to 2017 obtained from the Pelotas meteorological station and from 1968 to 2017 from the Santa Maria meteorological station. Water deficit (mm) in the subperiods and soybean development cycle was obtained from the calculation of evapotranspiration and daily sequential crop water balance. Data of water deficit were subjected to a probability distribution analysis, in which the exponential, gamma, lognormal, normal, and Weibull probability density function (pdf) adjustments were tested using chi-square and Kolmogorov–Smirnov adhesion tests, with a 10% significance level. The water deficit is lower in the Pelotas region than in Santa Maria. Sowings performed from 11 and 1 November present the lowest risk of occurrence of water deficit throughout the soybean cycle in Santa Maria and Pelotas, respectively. Risk of water deficit decreases for the beginning of flowering–beginning of seed (R1–R5) subperiod when soybean sowing occurs from the beginning of November.

ADJUSTMENT OF PROBABILITY FUNCTIONS TO WATER EXCESS AND DEFICIT IN SOYBEANS CULTIVATED IN LOWLAND SOILS MATEUS POSSEBON BORTOLUZZI¹; ARNO BERNARDO HELDWEIN²; ROBERTO TRENTIN³; ASTOR HENRIQUE NIED²; JOCÉLIA ROSA DA SILVA4 E LEIDIANA DA ROCHA4 1 Faculdade de Agronomia e Medicina Veterinária, Universidade de Passo Fundo, BR 285, São José, 99052-900, Passo Fundo, RS, Brasil. mateusbortoluzzi@upf.br 2 Departamento de Fitotecnia, Universidade Federal de Santa Maria, Avenida Roraima, n° 1000, Camobi, 97010-900, Santa Maria, RS, Brasil. heldweinab@smail.ufsm.br; astor.nied@ufsm.br 3Departmento de Fitotecnia, UFPel, Campus Universitário, s/n, 96010-610, Capão do Leão, RS, Brasil. roberto.trentin@ufpel.edu.br 4 Programa de Pós-graduação em Agronomia, Universidade Federal de Santa Maria, Avenida Roraima, n° 1000, Camobi, 97010-900, Santa Maria, RS, Brasil. joceliarosa.s@gmail.com; leidi-r1@hotmail.com 1 ABSTRACT The objective of this study was to verify the fit of exponential, gamma, lognormal, normal and weibull probability density functions (pdf) to water deficit and excess accumulated data during soybean subperiods and development cycle. Historical series of meteorological data obtained from Pelotas and Santa Maria meteorological stations (RS) were utilized. The soybean development simulation was performed for cultivars from the relative maturity group (RMG) between 5.9-6.8, 6.9-7.3 and 7.4-8.0 on eleven sowing dates from September 21 to December 31. Daily sequential water balance was calculated with water excess (days) and water deficit (mm) data to adjust each pdf to the observed data. The better adjustment frequency for water excess data in the soybean cycle was obtained with normal pdf in Santa Maria and weibull and gamma in Pelotas. Regardless of the location, the lognormal pdf presented the best fit for the water deficit data in the soybean cycle. In both locations, normal and weibull pdf demonstrated the best performance for water excess in the subperiods gamma, lognormal and exponential pdf for the water deficit. Keywords: Glycine max, risk analysis, sowing date, historical series. BORTOLUZZI, M. P.; HELDWEIN, A. B.; TRENTIN, R.; NIED, A. H.; DA SILVA, J. R.; DA ROCHA, L. AJUSTE DE FUNÇÕES DE PROBABILIDADE AO EXCESSO E DÉFICIT HÍDRICO NA SOJA EM TERRAS BAIXAS 2 RESUMO O objetivo deste trabalho foi verificar o ajuste das funções densidade de probabilidade (fdp) exponencial, gama, lognormal, normal e weibull aos dados de déficit e excesso hídrico, acumulados durante subperíodos e ciclo de desenvolvimento da soja. Foram utilizadas séries históricas de dados meteorológicos obtidos das estações meteorológicas de Pelotas e de Santa Maria, RS. Foi simulado o desenvolvimento da soja, para cultivares de grupo de maturidade relativa (GMR) entre 5.9–6.8, 6.9–7.3 e 7.4–8.0 em onze datas de semeadura compreendidas entre 21 de setembro e 31 de dezembro. Calculou-se o balanço hídrico sequencial diário, sendo obtidos os dados de excesso hídrico (dias) e déficit hídrico (mm) para ajustar cada fdp aos dados observados. A maior frequência de ajuste para os dados de excesso hídrico no ciclo da soja foi obtida para a fdp normal em Santa Maria e fdp weibull e gama para Pelotas. A fdp lognormal foi a que melhor se ajustou aos dados de déficit hídrico no ciclo da soja, independentemente do local. Em ambos os locais, a fdp normal e a weibull apresentaram o melhor desempenho para o excesso hídrico nos subperíodos e as fdps gama, lognormal e exponencial para o déficit hídrico. Palavras-chave: Glycine max, análise de risco, data de semeadura, séries históricas.

The value 8.46 MJ m−2 d−1 is generally indicated as the radiation threshold for vegetable crops in tropical and subtropical climates. However, several studies indicate that mini tomato plants can be cultivated in greenhouse under lower solar radiation conditions. Therefore, the establishment of the actual radiation threshold for this group of tomatoes is necessary. The objective of this study was to define the relative influence of solar radiation and temperature on plant growth, and determine the lowest value of incoming global solar radiation inside the greenhouse by which there is a significant plant dry matter accumulation in the mild autumn/winter of southern Brazil. Mini tomato plants of hybrids Cherry Wanda® and Grape Dolcetto® were grown in NFT hydroponic system. Nineteen plant samples were collected periodically to obtain plant dry matter, leaf area, number of leaves, plant height and absolute and relative growth rates. The variables were related to the data of incoming global solar radiation and temperature inside the greenhouse. The results were submitted to analyses of variance, regression and clustering test. Cherry and Grape plants presented similar responses to the variation of solar radiation and temperature. However, Cherry plants presented greater leaf area and growth under these conditions. Temperature had an indirect influence on plant growth, while incoming solar radiation presented a direct influence on all evaluated variables. The solar radiation threshold for both cultivars of mini tomato was 3.63 MJ m−2 d−1.

The aim of this study was to derive a methodology for calculating a sequential water balance that accurately estimates the occurrence of excess water in soybeans cultivated in lowlands. We tested four calculation strategies of water balance associated with the simulation of soybean development, which differed on the calculation of rainfall and time of water drainage from the soil macropores. Data of volumetric moisture monitored in three soil layers throughout the soybean cycle in the 2014/15 agricultural year were used as a reference. Microporosity was used as a lower limit for the occurrence of excess water in the area. Excess water was considered to be whenever the daily volumetric soil moisture in the 0-100 mm layer was greater than 0.39 mm3 mm-3. Over the 111 days of measurement, soil moisture indicated the presence of excess water in 38 days. The traditional calculation strategy of water balance underestimated the occurrence of excess water, as well as the other strategies that considered effective precipitation in their formulas. The calculation strategy that considers that all the rainfall infiltrates in the soil and that the water from macropores is removed only by crop evapotranspiration exhibited good performance and indicated 35 days of excess water, being the most appropriate and recommended for determining excess water in lowland soybeans.

O objetivo deste trabalho foi avaliar os efeitos da luz e da temperatura sobre a germinação das sementes e o comprimento e produção de massa seca das plântulas de calêndula (Calendula officinalis L.). As sementes foram colocadas para germinar a temperaturas constantes de 15; 20; 25; 30 e 35ºC, na presença e na ausência de luz. O delineamento experimental utilizado foi inteiramente casualizado com quatro repetições. Constatou-se que a percentagem de germinação das sementes é maior à temperatura de 20ºC, e que temperaturas de 30 e 35ºC são prejudiciais à germinação, e afetam significativamente o comprimento das plântulas e a sua produção de massa seca. The effects of light and temperature were evaluated on seed germination and on the length and dry matter of marigold seedlings (Calendula officinalis L.). The seeds were placed to germinate at constant temperatures of 15; 20; 25; 30 and 35ºC, in the presence and absence of light. The experimental design used was of complete randomized plots with four replications. The percentage of seed germination was higher at 20ºC, and temperatures of 30 and 35ºC were harmful to germination and affected significantly the length of seedlings and their dry matter production.

The control potato late blight needs a great number of fungicide sprayings. These increase the costs of cropping and cause undesirable environmental impacts. The use of forecast systems to predict disease has the potential of reducing fungicide applications without reducing yield. The objective of this study was to evaluate the performance of Blitecast and Prophy systems as a reference model for predicting late blight potato and support decision of spray fungicides. Experiments were carried out during Spring 2004 and Autumn 2005, in Santa Maria, RS, Brazil. Meteorological data were measured in the center of the experimental area at 0.10 and 1.50 m above soil surface. Different accumulated severity values (VS) were calculated with 'Blitecast' (VS = 18, 24, 30, 36 and 42) and 'Prophy' (VS = 15, 20, 25, 30 and 35) forecast systems. These values were used to perform. Two additional treatments were the weekly sprays and without fungicides. The experimental design was a completely randomized, with four replications. Each plot had four rows plants with 5 m length. Late blight severity was evaluated in each three to five days. The fungicide spraying schedule based on Blitecast system with 18 accumulated severity values increased tuber yield at least 42.6 % compared to the control without fungicides treatment. It also reduced the number of sprayings by 25% during wet periods and 70% during dry periods compared to weekly sprayings. The efficiency of controlling late blight was similar to the weekly sprayings treatment in the treatments Bli18 e Pro15. The Prophy model predicted higher number of fungicide sprayings than the Blitecast system and did not improve disease control.

O objetivo deste trabalho foi estimar o filocrono em plantas de calêndula (Calendula officinalis L.) cultivadas em diferentes épocas de semeaduras. Realizaram-se três épocas de semeaduras: 06/04/2005, 23/06/2005 e 03/10/2006, no interior de uma estufa plástica com área de 240m2, instalada no campus da Universidade Federal de Santa Maria, UFSM. A semeadura foi realizada em vasos plásticos com capacidade volumétrica para cinco litros. O delineamento experimental foi inteiramente casualizado com 320 vasos em cada época, sendo distribuído em quatro fileiras de 80 vasos cada. Em uma planta de oito vasos de cada quatro fileiras, fez-se a contagem, semanalmente, do número de folhas emergidas da haste principal e na primeira haste lateral. Os dados do número de folhas foram correlacionados com a soma térmica diária acumulada, considerando-se uma temperatura base de 8°C. Constatou-se que o filocrono variou com a época de semeadura, sendo o menor valor igual 15,9°C dia folha-1, obtido na 2ª época de semeadura e o maior, igual a 24,5°C dia folha-1, na 1ª época na haste principal e 48,9°C dia folha-1 na semeadura de outubro na primeira haste lateral. The objective of this study was to estimate the phyllochron in calendula (Calendula officinalis L.) grown in different sowing dates. Three sowing dates (06/04/2005, 23/06/2005 and 03/10/2006) were performed inside a 240m2 plastic greenhouse at the Campus of the Federal University of Santa Maria, RS, Brazil. Sowing was in five liter plastic pots. The experimental design was a completely randomized with 320 pots on each sowing date and rows with 80 pots. The number of leaves in the main stem and oi the first lateral branch was counted on a weekly basis in one plant of eight pots. The number of leaves data was regressed against accumulated thermal time, assuming a base temperature of 8oC. The main stem phyllochron varied with sowing date, with the lowest value (15.9°C day leaf -1) obtained on the second sowing date, and the greatest value (24.5°C day leaf -1) obtained on the first sowing date. The greatest phyllochron on the first order lateral branch was 48.9°C day leaf -1 in the October sowing date.