Rodrigo dos Santos Godoi

Growth and yield of lettuce plants under salinity

Plantas de alface, cv. Vera, foram cultivadas em cinco niveis de salinidade em um dispositivo experimental composto por uma camada de areia de 0,15 m de profundidade. Foi empregada uma solucao nutritiva padrao, com a seguinte composicao, em mmol/L: 16,9 de NO3-; 2,0 de H2PO4-; 1,0 de SO4-; 4,0 de Ca++; 10,9 de K+ e 1,0 de Mg++, e, em mg L 1, 0,42 de Mn; 0,26 de Zn; 0,05 de Cu; 0,50 de B; 0,04 de Mo, e 4,82 de Fe quelatizado. Os cinco niveis de salinidade foram obtidos por variacoes na concentracao da solucao nutritiva padrao, atingindo valores medios de condutividade eletrica (CE) de 0,80; 1,93; 2,81; 3,73 e 4,72 para T1, T2, T3, T4 e T5, respectivamente. A solucao nutritiva em cada nivel de salinidade foi fornecida a partir de um reservatorio atraves de uma bomba submersa, durante 15 min, em intervalos diurnos de 90 min e noturnos de 420 min. Um dispositivo experimental inteiramente casualizado foi empregado, com quatro repeticoes e 20 plantas por parcela. Quatro plantas de cada tratamento foram coletadas aos 32 dias apos o plantio para determinar a massa seca da parte aerea e das raizes, a massa fresca da parte aerea, a area foliar e o numero de folhas. O numero de folhas por planta foi igual a 18, sem diferenca significativa entre os tratamentos. A massa seca de folhas aumentou 24,4% de T1 para T3. A massa seca do caule foi reduzida nos niveis salinos mais elevados, porem nao foi observada relacao dos tratamentos com a massa seca do caule e das raizes. Foi observado efeito positivo na massa fresca da parte aerea, a qual aumentou 28,5% de T1 para T2, decrescendo 16,5% de T2 para T5. O valor maximo estimado do indice de area foliar foi de 4,3 m2 m-2 para uma EC de 2,6 dS m 1. Concluiu-se que niveis salinos acima de 2,0 e 2,6 dS m 1 reduzem o crescimento e a massa fresca das plantas, respectivamente.

Cultivo sem solo do morangueiro

Strawberry is a very important crop in Europe and USA due to its nutritional and sensorial characteristics and its profitability. Nowadays, the traditional soil based crop production is being replaced by soilless growing systems, leading to higher yield and quality all over the year. Open systems with different kind of substrates in plastic bags or pots are mainly used, at plant densities from 8 to 12plants m-2. Fruit yield is in the range from 5 to 10kg m-2. In general, plants are grown at 0.8-1m height above the soil surface, to isolate them from the soil and to facilitate the crop management. There are variations in the composition of the nutrient solution, reflecting differences in the conditions of crop production. Plug plants are produced in containers with substrate. They are obtained from runner tips of in vitro propagated mother plants. In Brazil, the strawberry soilless culture is in its first steps. Production and economical results are rather unsatisfactory, and researches about more appropriated cropping systems for local conditions are needed. Therefore, it is necessary to search for sustainable soilless growing systems, mainly of the closed type, to maximize yield under high water and nutrient use efficiency. Plant propagation, facilities and nutrient solutions used in different countries are described. Finally, guidelines for soilless crop systems appropriated for this crop in Brazilian conditions are presented.

Produção e qualidade do morangueiro em sistemas fechados de cultivo sem solo com emprego de substratos

The objective of the research was to determine fruit production and quality of strawberry plants grown in three different closed soilless systems and two substrates. The experiment was conducted in a screenhouse at Department of Fitotecnia, UFSM, from April to November, 2006. The soilless growing systems were plastic bags, plastic troughs and growing beds, and the substrates were sand and the organic substrate Plantmax PXT®. A 3 x 2 factorial experimental design was used, with four replications. Drip fertigation was used in the plastic bags and sub-irrigation in the other two systems. A standard complete nutrient solution was used without any disposal of it during the experiment. Ripe fruits were harvested and production, firmness, acidity and soluble solids were determined. A significant interaction among substrates and systems was observed. In sand, a mean fruit production of 1017,4g plants-1 was obtained in plastic troughs, which was 8.13% e 8.33% higher than in plastic bags and growing beds, respectively. In the organic substrate, the higher fruit production was 1196,5g plants-1 in growing beds. It was 10.9% and 29.33% higher than that in plastic bags and plastic troughs, respectively. It was concluded that strawberry soilless production might be done without any disposal of nutrient solution during the cropping period. Fruit production was affected by both the growing system and the substrate, without any effect on fruit quality.

Crescimento e desenvolvimento do tomateiro cultivado em substrato com reutilização da solução nutritiva drenada

Two experiments were carried out in a plastic greenhouse in autumn and spring 2001. Sowing dates were February 17th and July 3rd, respectively. At 41 (1st experiment) and 36 days (2nd experiment) after sowing, plantlets were transplanted to 5.5 dm3 bags placed inside gullies, using a commercial substrate, in a plant density of 3.3 plants m-2. Treatments consisted of three nutrient solutions. In T1 treatment, fertilizer concentrations were, in mol. L-1: KNO3, 0.04: Ca(NO3)2, 0.027; MgSO4, 0.012. Phosphorus (P) was added by 1.5 g L-1 of superphosphate (20% P2O5), and micronutrients by a commercial mixture. For T1 plants, 1 L of the above nutrient solution was supplied once a week, containing 14.9 g L-1 of macronutrients. For T2 and T3 treatments the amounts of nutrients from T1 were applied in duplicate and triplicate, resulting in a total of macronutrient of 29.8 and 44.7 g L-1, respectively, supplied once a week. Drained volumes from each irrigation were collected and re-used in the next fertigations, after correcting nutrient concentrations in order to reach the original threshold level previously fixed for each treatment. Average electrical conductivity (EC) values of drained nutrient solution were 3.7; 6.8 and 8,9 dS m-1 at the first and 3.3; 5.2 and 7.4 dS m-1 at the second experiment, respectively for T1, T2 and T3. From 40 to 82 days after planting date (DAP) in autumn and 37 to 79 DAP in spring. Plants were periodically harvested to determine growth and development. In spring, ripe fruits on remaining plants were harvested and weighed to determine fruit yield. No significant differences were found for the number of fruits among treatments. In autumn, total and vegetative dry mass were lower on T3 plants, whereas fruit dry mass was higher. In spring, means of total and vegetative dry mass were lower on T3 plants, but fruit dry mass did not differs among treatments. Fruit yield decreased by effect of increasing values of EC. Based upon these results we concluded that it is possible to re-use drained nutrient solutions, when growing the tomato crop in substrates, and negative effects of salinity on fruit yield are observed only for EC values up to 4.9 dS m-1.

Closed soilless growing system for producing strawberry bare root transplants and runner tips

The objective of this work was to test a closed soilless growing system for producing bare root transplants and runner tips of two strawberry clones, using two categories of substrates. The system used corrugated roofing panels of fiber‑cement, over which a substrate layer was used as a growing bed. The nutrient solution was pumped from a reservoir toward the upper end of the roofing panels and drained back to a reservoir. Plant growth and development were determined for two advanced strawberry clones, grown in sand or in Plantmax organic substrate. Growth of the stock plants and the number and dry mass of bare root transplants were similar in the substrates, but bare roots differed in their crown diameters by substrate. For number of runner tips, no significant differences were found in total, small, and medium categories in the substrates. A mean production of about 590 runner tips per square meter and 145 bare root transplants per square meter was obtained. For both clones, a large number of bare root transplants and runner tips of adequate size were produced in the closed soilless growing system using sand or organic substrate.

Cultivo hidropônico da alface empregando substratos: uma alternativa a NFT?

Foi desenvolvido um dispositivo experimental para o cultivo da alface em sistema hidroponico fechado empregando substratos. As bancadas foram constituidas por telhas de cimento amianto, cujos canais foram preenchidos com brita basaltica. Sobre a brita foram dispostos os substratos, formando uma camada de 0,05 m de altura, com a superficie revestida com filme de polietileno opaco branco. As mudas foram produzidas em bandejas de poliestireno e plantadas em orificios feitos sobre a superficie do filme de polietileno. Uma solucao nutritiva completa foi fornecida diariamente, por meio de tubos gotejadores localizados na superficie da camada de substrato e abaixo do filme de polietileno. A solucao drenada foi recolhida por gravidade para dentro do reservatorio principal. Foram conduzidos dois experimentos, no periodo entre 16 de maio e 24 de junho e 1o e 28 de outubro de 2003, empregando as cultivares Regina e Mimosa e os substratos areia media e substrato orgânico Plantmax® Folhosas HA. No decorrer dos experimentos, houve diminuicao dos valores de pH da solucao nutritiva, tendo sido feita apenas uma correcao em cada um dos experimentos. No dia mais quente do experimento de primavera, a temperatura foi mais elevada na areia, sem diferenca significativa do substrato orgânico, cuja media situou-se 5,4oC acima da temperatura da solucao nutritiva e 0,4oC acima daquela do ar. As medias mais elevadas das variaveis de crescimento e desenvolvimento foram observadas no substrato orgânico no outono, enquanto, na primavera, foram constatadas nos tratamentos tendo areia como substrato. O emprego dos substratos permitiu uma reducao em torno de 92,4% no tempo de funcionamento da motobomba e simplificou tanto o manejo da fertirrigacao como os controles da solucao nutritiva.

Relação potássio-nitrogênio para o diagnóstico e manejo nutricional da cultura da batata

The objective of this work was to determine the maximum K dilution curve and the relationship with the N dilution curve, during growth and development of the potato crop, for nutritional diagnosis and fertilization purposes. Treatments consisted of nutrient solutions with K concentrations of 3.5, 5.5, 6.5, 8, and 9.5 mmol L-1. The completely randomized experimental design was adopted with four replications. Four plants were harvested, at weekly intervals, to quantify plant growth and to determine N and K tissue concentrations. The maximum K dilution curve was adjusted, and the maximum K uptake was determined, during crop growth and development. It was observed that maximum K concentrations might be estimated from critical N concentrations. Quantities of K fertilizers to be supplied to achieve a pre-fixed crop yield can be estimated from tissue N concentration.