Assessment of genetic diversity based on morphological, biochemical and physiological traits of black pepper (Piper nigrum L.) cultivars from Kerala

Abstract

Black pepper landraces and local cultivars maintained by farmers over centuries in different agroclimatic conditions in Kerala are useful for utilizing valuable allelic diversity in breeding programs. A survey conducted in the black pepper growing regions of Kerala identified 21 genotypes with superior yield and distinct characters. Observation of qualitative morphological traits revealed moderate variability among the black pepper genotypes. The dendrogram constructed using the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) method grouped 21 genotypes into 15 clusters at 73% genetic similarity and the similarity coefficient ranged between 0.47 and 0.81. Biochemical evaluation revealed considerable variations in their piperine (3.0–5.6%), essential oil (3.0–5.6%) and oleoresin (6.3–13.2%) contents. The principal component analysis could describe the evaluated traits as nine main and independent components, which were able to justify 86.59% of the total variance. Eigenvalues indicated that a majority of yield-related traits, viz., leaf petiole length, leaf length, leaf width, fresh spike yield, fresh berry yield and dry yield and physiological traits such as leaf thickness, relative water content and epicuticular wax, contributed to the total diversity of the black pepper germplasms. Based on the present investigation, genotypes such as G16, G15, G21, G1, G5 and G4 with considerable genetic divergence and desired qualities can be employed as good candidates in breeding programs.