Doses of sulfur at topdressing and organic compost supply at planting in the production, quality and content of macronutrients in lettuce seeds

The purpose of this study was to evaluate doses of sulfur applied at topdressing, with and without organic compost supply at planting, in the production, physiological quality and content of macronutrients in lettuce seeds. Ten treatments were evaluated in a 5x2 factorial scheme (five sulfur doses at topdressing x with and without application of organic compost at planting). The experimental design was a randomized block design, with four replicates. The sulfur doses applied at topdressing fertilization were 50, 100, 150 and 200 kg ha-1 of S, in addition to the control treatment (dose zero). Regarding the treatments with organic compost, the dose of 70 t ha-1 of compost (wet basis) was supplied at planting. The following characteristics were evaluated: seed production (mass and number of seeds per plant), seed quality (mass of one thousand seeds, first count of the standard germination test, germination percentage, and germination speed index) and content of macronutrients and mineral accumulation. The organic compost supply at planting increased seed production by 43% compared to the treatment without the application of organic compost, while the doses of sulfur did not affect the production of lettuce seeds. The supply of organic compost increased the accumulation of a great part of the macronutrients, except for the accumulation of calcium. The lettuce seeds quality was not affected by both the main treatments, the sulfur doses at topdressing and the organic compost supply at planting. The descending order of nutrients accumulated in the lettuce seeds was nitrogen> potassium> phosphorus> magnesium> calcium> sulfur.

Maturation and Resting of Sweet Pepper Fruits on Physiological Quality and Biochemical Response of Seeds

Abstract The post-harvest resting of the fruits can improve seed physiological quality ,once it allows the seed to complete the maturation process, so it has been a common practice in vegetable seed companies, however, there are a few studies of this technique in sweet pepper. The objective of this research was to evaluate physiological quality, and biochemical response of sweet's peppers in regarding on the stage of maturation and the post-harvest rest of the fruits. The experimental was conducted in a 4x2 factorial, being the first factor comprised four maturation stages (35, 50, 65 and 80 days after anthesis) and, the second the post-harvest management of fruits, with and without a temporary storage of seven days. Seeds were evaluated for water content, weight of thousand seeds, germination, vigor, superoxide dismutase, catalase and peroxidase activities, lipid peroxidation and hydrogen peroxide content. Fruit harvest time indicated is 80 days after anthesis (fruits 100% yellow) when seeds showed maximum germination and vigor. The post-harvest resting of the fruits was beneficial to seed physiological quality, weight of one thousand seeds and to reduce hydrogen peroxide content. Seeds of higher physiological quality showed lower superoxide dismutase and catalase enzyme activity, so they can be used as a marker of physiological quality in sweet pepper seeds.