Effect of foliar application of nitrogen, phosphorus and potassium in cotton (Gossipium hirsutum, L. var. I.A.C. 12) as evaluated by yield and foliar analysis

Abstract

This work was carried out on latosolic soil type, called "terra roxa estruturada", Luiz de Queiroz serie. It was installed in November 1968 and was finished in May 1969, using the I.C.A. 12 (G. hirsutum L.) variety. The objectives of this work were: 1 - Evaluate the effect of foliar spraying in the yield increase. 2 - Evaluate the effect of foliar spraying by foliar diagnosis, and determine correlations between the yield and nitrogen, phosphorus and potassium concentrations in the petioles of leaves of productive and unproductive branches. 3 - The experimental design consisted of complete randomized blocks with 3 replications with part of the treatments in a 4 x 3 factorial arrangement; 4 representing the number of levels and 3 the number of fertilizers. Apart from these, 12 treatments were included: N0P0K0 , N1P3K3 , N3P1K3 , N3P3K1 and N3P3K3 Each block consisted of 21 plots because the N0P0K0 and N3P3K3 treatments were replicates 3 times within each block, in order to increase the accuracy of the respective mean values. The levels of these elements were as follows. In the soil and foliar fertilization the fertizer used as a source of nitrogen was urea (46% N), as a source of phosphorus concentred superphosphate (45% P2O5) and as a source of potassium, potassium chloride (60% K2O). The results obtained show that: 1 - No statistical differences were found in the production of branch cotton. Then mean value reached 3,366.09 kg/Ha. it should be pointed out, however, that in the relative percentage with respect to the check tratment there were increases of 17,15%, 20,50% and 23,01%. These were obtained with the N3P3 + K2 *, N3K3 + P3* and P3K3 + N2* treatments respectively. 2 - The mean percentage concentrations of nitrogen, phosphorus and potassium which were found in the petioles were the following: No statistical differences were found, for each sampling, in the concentrations of these three nutrients in the petiole of the respective branch. The first sampling was carried out 86 days after germination and the second 116 days after germination. 3 - Total significant correlations were found in the percentages of potassium with yield in the first sampling for petioles of leaves of productive branches and in the second sampling for petioles of both productive and unproductive branches : Total correlations were also obtained between the phosphorus percentages and yield in the first sampling for petioles of both types of branches and in the second sampling just for petioles of productive branches: No statistical difference was found, in relation to the type of sampling, between the correlations of the petioles of leaves of both types branches.