Lettuce plants, cv. Vera, were grown under five salinity levels in a hydroponical experimental set-up using a 0.15 m deep sand growing bed. A standard nutrient solution was used, with the following composition, in mmol L-1: 16.9 NO3-; 2.0 H2PO4-; 1.0 SO4- 4.0 Ca++; 10.9 K+ e 1.0 Mg++, and, in mg L-1, 0.42 Mn; 0.26 Zn; 0,05 Cu; 0,50 B; 0,04 Mo, and 4.82 chelated Fe. The five salinity levels compared as treatments were obtained by varying the concentration of the standard nutrient solution, reaching average electrical conductivities (EC) of 0.80; 1.93; 2.81; 3.73 and 4.72 dS m-1, for T1, T2, T3, T4 and T5, respectively. The nutrient solution at each salinity level was supplied from a reservoir by means of a flooded-type electrical pump, for 15 minutes, at intervals of 90 minutes during the day and 420 minutes during the night. A completely randomised experimental design was used with four replications and 20 plants per plot. Four plants of each plot were harvested at 32 days after planting, to determine shoot and root dry mass, shoot fresh weight, leaf area and number of leaves per plant. Number of leaves was 18 per plant and was not affected by treatments. Dry mass of leaves increased 24,4% from T1 to T3. No relationships were found on data from stem and root dry mass. A positive effect of EC was recorded on shoot fresh mass, which increased 28.5% from T1 to T2, and decreased 16.5% from T2 to T5. Maximum LAI estimated value was 4.3 m² m-2 for an EC of 2.6 dS m-1. Salinity levels above 2.0 and 2.6 dS m-1 reduce fresh yield and plant growth, respectively.

The experiment was conducted at Universidade Federal de Santa Maria, Rio Grande do Sul State, Brazil, to determine the effect of shading on tomato plants grown in a greenhouse. Sowing was done on July 4th and planting on August 27th, 2000, in a plant density of 3.3 plants m-2, using an organic commercial rooting medium. Water and nutrients were supplied on a daily basis using a nutrient solution. Two polyethylene tunnels (2.20 m height, 5 m width, 15 m length) were used. In the first plastic tunnel, used as control, the transmissivity of global radiation was 83% and plants were conducted as a commercial crop. In the second tunnel, plants were grown under a 52% shading screen. Plant growth and development were measured at 19; 26; 33; 40; 47; 54; 61; 75 and 89 days after beginning of anthesis. Daily average solar radiation in the first tunnel from planting time to the end of the experiment was 12.4 MJ m-2 day-1, whereas in the shaded tunnel it was 5.0 MJ m-2 day-1. Number of fruits per square meter did not differ significantly between the unshaded control and shaded tomato plants. At the last harvest, dry mass from unshaded and shaded plants differed significantly, with values of 974.9 g m-2 and 762.5 g m-2 for total dry mass, 550.1 g m-2 and 419.74 g m-2 for fruits, and 424.75 g m-2 and 342.74 g m-2 for vegetative organs, respectively. Total plant growth was reduced to 21.7% by shading, but plants continued to grow, in spite of the radiation level below the trophic limit of 8.4 MJ m-2 day-1. To establish the climatic suitability of horticultural crops in different regions, it should be advisable to take in account other variables than solar radiation.

RESUMOTrês diferentes materiais foram avaliados quanto ao seu potencial de uso como substrato para o cultivo do tomateiro. Os experimentos foram realizados no Departamento de Fitotecnia da UFSM, em Santa Maria-RS e os materiais avaliados foram: húmus proveniente da minhocultura, casca de arroz e substrato comercial (Plantmax Folhosas). O substrato comercial foi comparado no seu estado original correspondente a primeira utilização e também na sua segunda utilização com a mesma cultura. A casca de arroz foi comparada no seu estado puro e também em mistura com solo da região na proporção de 50% de cada componente. A caracterização física foi efetuada pela determinação da densidade e da massa úmida e pelo cálculo do volume retido e da capacidade máxima de retenção de água. A avaliação qualitativa dos substratos foi realizada por meio de avaliações do crescimento e produção de frutos de dois cultivos de tomateiro, respectivamente no outono-inverno e primavera-verão do ano de 1997. O húmus apresentou características físicas similares ao substrato comercial, enquanto que a casca de arroz reteve volume de água aproximadamente 50% inferior aos outros dois substratos avaliados. Porém, essa diferença diminuiu quando a casca de arroz foi misturada com o solo. O crescimento das plantas na casca de arroz foi inferior e a produção de frutos atingiu apenas 56% daquela obtida nos outros substratos. Tanto a mistura de casca de arroz e solo como os outros substratos avaliados se mostraram apropriados para o cultivo do tomateiro fora do solo. Palavras ABSTRACTEvaluation of substrates for growing tomatoes in soilless culture.Three different organic materials were tested at the UFSM, Santa Maria, Brazil, as substrate for growing tomatoes in soilless culture. Humus originated from the digestion of organic materials by earthworms, rice husk, and a commercial substrate "Plantmax Folhosas" were used. Two successive cycles of tomato plants were evaluated, by replacing old plants with young ones after the first cycle of the crop. Rice husk was compared solely in a homogeneous form and as a mixture with soil in a 50% basis. Substrates were characterized by physical parameters of bulk density, wetness and through calculation of the volumetric water content and maximum capacity of water retention. Quality of substrates was evaluated by measuring growth and yield of two successive tomato crops, in the Autumn and the Spring of 1997. Comparisons between humus and the commercial substrate showed similar physical characteristics, while volumetric water content of rice husk was about 50% lower. This difference was reduced when soil was added to the rice husk. Growth of tomato plants on rice husk was lower and fruit yield achieved a maximum value of 56% of that observed on the two other substrates. Humus, the commercial substrate "Plantmax Folhosas" and the mixture of rice husk with soil may be used successfully for growing tomatoes in soilless culture.

RESUMO O morangueiro é uma cultura importante em vários países, principalmente nos Estados Unidos e na Europa INTRODUÇÃOO interesse comercial pelo morangueiro é grande em muitos países. A coloração, o aroma e o sabor da fruta, assim como suas propriedades nutritivas, fazem do morango um produto muito apreciado pelos consumidores. O maior consumo ocorre in natura, mas pode ser processado em múltiplas formas, tais como em geléias, caldas, sucos e polpa congelada. É consumido também em laticínios, para a I Programa de Pós-graduação em Agronomia

RESUMO O armazenamento adequado dos tubérculos é muito importante para manter o equilíbrio da oferta de batata no mercado e para a obtenção de tubérculos-semente em adequado estádio fisiológico no momento do plantio. O objetivo deste trabalho foi determinar o efeito de diferentes temperaturas de armazenagem no envelhecimento fisiológico de tubérculos de três clones de batata produzidos durante o outono e a primavera. O experimento foi desenvolvido em um fatorial de três clones (Asterix, SMIJ461-1 e SMINIA793101-3) por quatro temperaturas de armazenamento (4, 8, 12 e 25 ºC) e duas épocas de plantio (outono e primavera) no delineamento experimental inteiramente casualizado, com quatro repetições. As avaliações foram em intervalos de 30 dias, do início até os 180 dias de armazenamento. O armazenamento refrigerado prolongou a dormência dos tubérculos, reduzindo o número de brotos e evitando o apodrecimento; as temperaturas de 4 e 8 o C impediram a brotação dos tubérculos produzidos no outono. A perda de massa fresca e a respiração dos tubérculos aumentaram com o tempo e a temperatura de armazenamento. A época de plantio altera o comportamento fisiológico dos tubérculos durante o armazenamento. O armazenamento à baixa temperatura (4 e 8 ºC) é eficaz para retardar o envelhecimento fisiológico.Palavras-chave: Solanum tuberosum L., temperatura de armazenamento, perdas pós-colheita, respiração, batata-semente. ABSTRACT PHYSIOLOGICAL AGING OF POTATO TUBERS PRODUCED DURING FALL AND SPRING GROWING SEASONS AND STORED UNDER DIFFERENT TEMPERATURESAdequate tuber storage is necessary to maintain a good availability of potato tubers in the market and to get seeds with adequate physiological age at planting. The objective of this work was to determine the effect of different storage temperatures on tuber physiological aging of three potato clones produced during fall and spring growing seasons. The experiment was carried out as factorial of three clones (Asterix, SMIJ461-1 and SMINIA793101-3) by four storage temperatures (4, 8, 12 and 25 ºC) and two growing seasons (fall and spring) in a random design with four replications. At 30-day intervals, tubers were evaluated from the beginning to 180 days of storage. Cold storage increased dormancy period, reduced sprout number and kept health tubers. Tubers produced during fall season did not sprout at the storage temperatures of 4 and 8 o C. Tuber fresh weight loss and respiration increased with storage period and temperature. Crop growing season changes tuber physiological aging during storage. Storage in low temperature (4 and 8 ºC) conditions is efficient to slow down tuber aging.