Macronutrients in caribean pine II: corresponding sufficiency and defficiency internal levels

Abstract

A pot experiment was conducted in a green house in Piracicaba, Brazil, in order to determine, the effects of omission in growth, the corresponding internal levels and the efficiency of macronutrients use for young plants of P. oaribaea var. hondurensis, P. oaribaea var. bahamensis and P. caribaea var. caribaea. The following treatments were employed: complete, without nitrogen, without phosphorus, without potassium, without calcium, without magnesium, and without sulphur. Washed sand was used as a substrate, being the plants watered twice a day with the corresponding nutrient solution. After the deficiency symptoms establishment, the plants were cut and separated in upper needles, lower nedles, branches and roots, dried at 60-70°C, weighed, ground and analysed for N, P, K, Ca, Mg and S concentrations . The internal levels in needles under complete and deficient treatments are: N% 1.33 and 0.54, P% 0.03 and 0.02, K% 1.76 and 0.34, Ca% 0.23 and 0.04, Mg% 0.22 and 0.04, S% 0.24 and P0.09 for P. caribaea var. hondurensis; N% 1.30 and 0.51, P% 0.02 and 0.02, K% 1.51 and 0.35, Ca% 0.14 and 0.05, Mg% 0.15 and 0.08, S% 0.16 and 0.06 for P. caribaea var. bahamensis and; N% 1.18 and 0.43, P% 0.01 and 0.02, K% 1.51 and 0.34, Ca% 0.15 and 0,04, Mg% 0,13 and 0.08, S% 0.11 and 0.06 for P. caribaea var. caribaea. P. caribaea var. hondurensis is less effective in macronutrient absorption.