Aliny Heloísa Alcântara Rodrigues

Lettuce cultivation is an activity of great economic importance; therefore, the use of techniques for better use of space and better-growing conditions should be evaluated. The objective of this study was to evaluate the development and yield of garden lettuce grown under different soil coverings and plant spacing. The study was conducted in an experimental area located at the School of Agronomy of the Federal University of Goiás, in the city of Goiânia, Goiás. The experiment was conducted in a randomized block design with subdivided plots in four replications. The plots consisted of three soil coverings (soil without cover, straw, and plastic cover) and the subplots in three planting spacing (PS1 = 25 x 20; PS2 = 25 x 25; PS3 = 25 x 30 cm), totaling nine treatments. The evaluations occurred when the plants presented their complete development, being evaluated: plant diameter, fresh head mass, stem mass, number of leaves, stem height; stem diameter; relative chlorophyll index; yield; and utilization, corresponding to the percentage of fresh marketable mass. It was found that the use of soil cover can favor the densification of lettuce cultivation. For cultivation on soil without cover or with the use of plastic as a cover, the cultivation spacing must be greater.

Vitamin application can optimize plant growth and grain yield of rice crop due to its beneficial effect on many plant physiological characteristics. The present study was conducted to evaluate the effects of niacin and thiamin applied as seed soaking or foliar spray on the morphological and productive characteristics of upland rice crop (Oryza sativa L., cv. Primavera), grown under greenhouse conditions. The experiment was arranged in a randomized block design in a 4 x 2 factorial scheme, with four replicates. The treatments consisted of the application of vitamins (control; 200 mg L-1 thiamin; 200 mg L-1 niacin; and 100 mg L-1 thiamin + 100 mg L-1 niacin) and two application methods (seed soaking and foliar spraying). Morphological and productive characteristics of the rice plants were evaluated. The exogenous application of thiamin and niacin, regardless of the application method, has a beneficial effect on the growth of upland rice plants, but does not increase the grain yield of the crop.

Rice is an important source of energy for a large part of the world’s population. The development and application of technologies that contribute to the improvement of production forthis grain have great importance. The objective of this study was to evaluate the influence of rice seed immersion in a niacin solution on plant development, physiology and production. Thetreatments were defined by a combination of two immersion times for the seeds (12 h and 24 h) in four niacin concentrations (0.00, 100, 200 and 300 mg L-1) distributed in five replicates. Characteristics relating to seedling emergence, plant vegetativedevelopment, relative indices of chlorophyll and grain yield were evaluated. We verified that the immersion of the seeds for 12 h gave higher relative indices of chlorophyll, whereas immersion for 24 h increased the speed of emergence and the number of tillers and panicles. The doses of niacin positively affected the relative chlorophyll indices and the production characteristics, up to a maximum concentration of 172.57 mg L-1. We concluded that the immersion of rice seeds for 24 h increased the speed of seedling emergence, leaf number, and panicles per area. However, the relative indices of chlorophyll in leaves decreased. The use of niacin promoted the numbers of spikelets per panicle, fertility of the spikelets and the weight of 1000 grains, besides increasing the relative index of chlorophyll in the leaves of rice plants.

A cultura do melão é responsiva ao ambiente de cultivo e às técnicas de produção utilizadas, sendo estes fatores cruciais para a obtenção de frutos de maior qualidade. Desta forma, objetivou-se estudar, o crescimento vegetativo, o potencial produtivo e a qualidade de frutos de meloeiro Cantaloupe em função da redução do espaçamento em dois ambientes de cultivo. Em delineamento experimental de blocos ao acaso, plantas de meloeiro, cultivar Trinity, foram cultivadas em campo aberto e ambiente protegido, sob cinco espaçamentos entre plantas (15, 25, 35, 45 e 55 cm). Observou-se que a taxa de crescimento de plantas, a taxa de emissão foliar, bem como a espessura de casca e polpa, o teor de sólidos solúveis, e o ratio foram superiores sob cultivo protegido. Em relação aos espaçamentos, verificou-se que seu aumento influenciou, de forma linear e positiva, as características de massa seca de plantas, massa fresca de frutos e espessura da polpa. No entanto, o aumento da densidade de plantas aumentou a produtividade. Para velocidade de crescimento, velocidade de emissão foliar e comprimento e circunferência de fruto constataram-se pontos de máximos de 47,50; 53,75; 49,95 e 47,51 cm, respectivamente. Em vista dos resultados, para regiões com condições semelhantes à do presente estudo, o cultivo do meloeiro Cantaloupe é favorecido em condições de cultivo protegido e espaçamentos entre 45 e 55 cm na linha de plantio.