REPRODUCTIVE PHENOLOGY AND MOLECULAR CHARACTERISATION OF Moringa oleifera LAM. LANDRACES IN RAIN FOREST ZONE OF SOUTHWESTERN NIGERIA

Abstract

Local adaptation of multipurpose tree species such as Moringa oleifera has resulted in the emergence of landraces, which could influence selection for mass propagation. It has been established that knowledge on landraces affects decisions on germplasm collection for propagation of Moringa oleifera. However, critical information on the reproduction and genetic characteristics of different landraces are limited. Therefore, the flowering and fruiting patterns, pod morphology, seedling growth and genetic characteristics of Moringa oleifera in Southwestern Nigeria were investigated. Two Moringa plantations were purposively selected from each of eight locations: Abeokuta, Akure, Erinjiyan, Ijare, Ijari, Ijaye, Omu, and Oyo, based on availability. Five trees were randomly selected from four corners and the centre of a 20m by 20m plot, demarcated at the centre of each plantation. These trees were used to assess phenology: onset and duration of flowering and fruiting (days), pod morphology and maturity index [duration before pod colour change (days)], for 24 months. Pods (300) were collected from each location and measured for length (cm), diameter (mm), seed weight (g) and number of seed/pod (NS). Seeds extracted at each stage of maturity were subjected to germination test using standard procedures. Sixty uniformly growing seedlings were selected per location and monitored for height (cm), collar diameter (mm) and number of leaves for six months. Genetic characteristics of five accessions/plantation (n=80) were determined using five microsatellite markers (MO8, MO15, MO48, MO61, MO64). Number of Alleles (NA), allele frequency, genetic diversity and Polymorphic Information Content (PIC) were determined. Data were analysed using descriptive statistics, Analysis of Molecular Variance (AMOVA), Cluster Analysis and ANOVA at α0.05. Flowering (April-June; August-October) and fruiting (June-September; October-February) occurred twice a year; while duration of flowering (43.5-44.3) and fruiting (154-160) in days were similar across locations. Three stages of pod colour change: green (26.5-28.8), yellow (82.6-92.3) and brown (25.8-31.8) were observed. Abeokuta (40.0±1.7) had the highest pod length, while Erinjiyan (27.6±0.6) had the least. Pods from Akure (16.4±3.2) had the least diameter while Abeokuta (19.5±2.9) had highest. Seed weight was significantly highest (31.4±1.7) at Omu and least (17.2±1.0) at Ijari, while NS ranged from 12.9±3.3 (Erinjiyan) to 17.9±3.3 (Akure). Seed germination was highest (90.7±0.3%) for yellow pods and least (30.7±0.9%) for green. Height was significantly highest (112.7±1.4) for seedlings from Ijari and least (76.9±0.8) for those from Omu. Seedling collar diameter ranged from 21.7±0.6 (Akure) to 37.4±0.9 (Erinjiyan). Ninety-six alleles with an average of 9.6±0.6 alleles/locus in each accession were amplified. Allele frequency and gene diversity ranged from 0.2% to 0.5% and 0.7% to 0.9%, respectively. The highest PIC (0.9) occurred in MO64, while MO48 had the least (0.6). There were significant differences in intra-specific (48%) and inter-specific (52%) genetic diversity of the sampled populations. Five clusters were identified with similarity coefficients that ranged from 0.1 to 0.4. Moringa oleifera population in Southwestern Nigeria exhibited extensive and simultaneous flowering and fruiting patterns. Pod and seed morphology were location dependent and influenced seedling growth. Five landraces of Moringa oleifera were identified and this has implications in germplasm selection for propagation