'The Relationship between Nutrient Content of Leaf Segments, Rates of Potassium, Yield and Quality of Pineapple (Ananas Comosus) Merr L. Var. Smooth Cayenne in the Coastal Savannah Zone of Ghana

Abstract

Plant nutrition holds the key to increased and sustained yields and the production of good quality pineapple fruit. Potassium plays a vital role in obtaining higher yields and good quality fruit. A good knowledge about the nutrient status of the plant is important for the correction of nutrient deficiencies and/or imbalances which tend to influence yield and quality of the fruit. This study was initiated to determine the appropriate leaf segment; viz. the nonchlorophyllous, chlorophyllous or the whole D-leaf to use for leaf analysis, and the effect of K on nutrient composition, growth, yield, and quality of pineapple. Field trials were conducted at three locations (i.e. Agricultural Research Station, Pokuase, Silwood and Parrico Farms in the Aburi/Nsawam areas) in the Coastal Savannah Zone of Ghana. The main export variety of pineapple, the Smooth Cayenne was used. Four rates of K, viz: 200, 300, 400 and 500 kg K/ha were used as main treatments. Leaf samples were taken at 8 months to study the growth of pineapple. A second sampling was carried out at 10 months to determine in addition to the above D-leaf N, P, K, Ca and Mg content. Mean fruit weight, titrable acidity and total soluble solids (T.S.S) of harvested fruits were also determined. The contents of N, P, K, Ca and Mg ranged between 1.0 - 1.7 % for N, 0.1 - 0.3 % for P, 2.2 - 4.6 % for K, 0.3 - 0.8 % for Ca and 0.5 - 1.2 % for Mg. The values obtained reflected adequate amounts. Results of soil analyses showed similar adequate levels. Nutrient contents differed significantly in the various segments of the D-leaf.

For N it was in the order whole D-leaf > chlorophyllous > non Chlorophyllous segment. For P, K, Ca, and Mg however, the non-chlorophyllous segment generally showed higher contents than the chlorophyllous or whole D-leaf. The non- chlorophyllous and whole D-leaf showed superiority over the chlorophyllous segment in the determination of nutrient content. Increasing K application influenced the leaf content of the other nutrient elements N, P, Ca and Mg. For N an increasing trend was observed whereas a decreasing trend was noted for P, Ca, and Mg. Potassium application significantly influenced dry matter content, mean fruit weight and acidity. The application of 500 kg K/ha caused significant yield increases over the 200 kg K/ha rate. No such yield differences were observed between 200, 300, and 400 kg/ha K rates. The application of between 200 - 300 kg K/ha was adequate for smooth cayenne fruit weighing between 1.6 - 1. 8 kg (which satisfies the (European) export market) for the Pokuase and Silwood farms area. Significant correlations were observed between either leaf N, K or Mg with dry matter content, yield and acidity. These correlations were better in some segments than in others. N was better correlated with yield and acidity in the non-chlorophyllous segment whilst P correlated better in the whole leaf segment of the D-leaf. Potassium correlated equally with acidity in both the whole D-leaf and the non-chlorophyllous segment.