Genetic diversity assessment of black pepper (Piper nigrum L.) cultivars of Western Ghats

The Western Ghats of Kerala, the centre of origin of black pepper (Piper nigrum L.), hold a rich repository of landraces and local cultivars, that farmers have maintained over centuries. A survey conducted in these regions identified 21 genotypes with superior yields and distinct characteristics, reflecting the diverse genetic makeup of black pepper across agroclimatic conditions in the state. Moderate variability was observed among these genotypes in qualitative morphological traits, but it was still significant enough to differentiate them. Using the Unweighted Pair Group Method with Arithmetic Mean (UPGMA), the genotypes were grouped into 15 clusters at 73 % genetic similarity, indicating shared characteristics and unique differences. Biochemical evaluation revealed variations in their piperine (3.0–5.6 %), essential oil (3.0–5.6 %) and oleoresin (6.3–13.2 %), which could have implications for flavour, aroma and medicinal properties. Principal Component Analysis (PCA) identified 9 main and independent components explaining 86.59 % of the total variance, with yield-related and physiological traits contributing significantly to the overall diversity. Genotypes G16, G15, G21, G1, G5 and G4 exhibited considerable genetic divergence and desirable qualities. This highlights the potential for leveraging these genotypes to develop improved black pepper varieties with enhanced traits such as yield, quality and resilience to various environmental conditions. The study provides insights into the genetic and biochemical diversity of black pepper germplasm in the Western Ghats of Kerala, offering a foundation for future breeding efforts to enhance the productivity and sustainability of black pepper cultivation.