Effect of nutrient omission in the development of sunflower BRS-122 in greenhouse conditions

Sunflower ( Helianthus annuus L.) is responsible for 13% of all vegetable oil produced in the world. These plants’ development depends on the mineral elements that have essential and specific functions in their metabolism. In this sense, visual diagnosis consists of comparing the appearance of a plant that has received all the necessary nutrients with one that has suffered the omission of one or more nutrients. Therefore, this study aimed to evaluate the absence effects of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S) and iron (Fe) elements on the growth of sunflower, BRS-122 cultivar, in order to identify and describe the visual symptoms caused by the absence of such nutrients. The experiment was carried out in a greenhouse and consisted in a completely randomized design with three replications and eight treatments using a diagnostic subtraction technique. The symptoms of the deficiencies were observed and evaluated through biometric parameters (plant height, stem diameter, number of leaves, and leaf area) as well as by visual aspects. The absence of N, P, K, Ca and Fe in the nutrient solution severely affected the sunflower plants, preventing their vegetative growth and consequently their development. The negative interference of the Mg omission in sunflower growth was slower than the observed for nitrogen, phosphorus, potassium, and calcium giving more significant results from 40 days after sowing (DAS). The absence of nutrients gave clear evidence of the distinct effects that the omission of each element can cause on the visual aspects of sunflower plants.