Estudos sôbre a Alimentação Mineral do Abacaxí (Ananas sativus) Sch

Pineapple plants when grown in the greenhouse by the sand culture technique in order to study the effects of deficiencies of macronutrients in growth, yield, leaf and fruit composition, the main results were the following. As a result of the several treatments, yield decreased in the order: Complete Minus Mg Minus S Minus Ca Minus K; nitrogen and phosphorus deficiente plants did not bear fruit.  Leaf analyses (see Table 5-1) showed that the ommission of given element from the nutrient solution always caused a decrease in its level in the green tissue.  As seen in Table 5-2 the lack of macronutrients had certain effects on fruit composition: acidity increased in all cases excet in the minus Mg fruits; ash usually decreased reaching its lowest valued in fruits from the minus K plants; when compared to fruits picked in the "normal" plants, those lacking K showed a marked decrease both in brix and in total sugars as well; sulfur deficiency also brought a net reduction in the sugar content. Table 5-1. Levels of macronutrients found in pinapple leaves. Elements                                 Treatment                         Percent of dry matter Nitrogen (N)                             Complete                                         1.29          Minus N                0.78    Phosphorus (P)                         Complete                                         0.12        Minus P                                            .05         Potassium (K)                           Complete                                         2.28                                                      Minus K                                          0.16         Calcium (Ca)                            Complete                                         1.19                                                      Minus Ca                                        1.10         Magnesium (Mg)                       Complete                                         0.41                                                      Minus Mg                                         .29         Sulfur (S)                                Complete                                         1.00                                                       Minus S                                            .65        Table 5-2. Effects of macronutrients deficiency in yield and fruit characteristics. Treatment      Ave. weight of      Acidity         As per       Brix           Total sugars                      fruits (gm)         per cent         cent                          per cent    Complete          1.031                1.16             0.40       14.7                10.8        Minus N       no                fruit            was                produced                    Minus P       no                fruit            was                produced                   Minus K               246                1.44            0.26        11.9                 8.3   Minus Ca             513                1.40            0.35        17.8                14.3   Minus Mg             957             0.97            0.38        15.4                13.0   Minus S               576                1.42            0.46        17.1                 6.5