Epochs of leaf tissue sampling for evaluation of primary macronutrients content in Fertigated tomato at coarse sand

The study aimed to evaluate the magnitude of correlation between tomato yield and primary macronutrients content at leaf tissue sampled in different epochs. It was used the hybrid Paronset, cultivated in greenhouse in the fall/winter season, in a fertigation system in pots with coarse sand. Electrical conductivities of 0.8; 1.6; 2.4 and 3.2 d Sm-1 were used in a randomized block design with ten replications to induce variation of contents of primary macronutrients in the leaves and tomato fruit yield. It was collected the index leaf in three different epochs of the cycle, at 60, 85 and 110 days after transplantation (DAT), respectively above the first, second and third cluster emitted (chronological order) in the main stem, determining the N, P and K contents (g kg-1). It was evaluated the fruit absolute yield (kg plant-1) and relative yield (%), correlating the last one with the nutrients contents by the Spearman coefficient. It was observed higher and more significant correlation, for all nutrients evaluated, with the leaf collected above the second cluster, at 85 DAT, demonstrating to be the one, in these conditions, that most reflects the plant nutritional status regarding to N, P and K.