PJB-2018-116
TRENDS IN REGIONAL AND CHRONOLOGICAL DIVERSITY OF MAIZE (ZEA MAYS L.) GERMPLASM IN CREOLIZED INFORMAL SEED SYSTEM OF PAKISTAN
Muhammad Amir Maqbbol
Abstract
Extensive collection of maize germplasm was conducted across the Pakistan to probe the trends in genetic variability at regional levels and chronological periods. Total 290 accessions were collected from 6 different provincial regions. These were comprised of chronological time periods; 1980-1984, 1985-1990, 1991-2000, 2001-2007 and 2008-2016. Data for different agronomic and yield related traits was subjected to statistical analysis. Mean comparison showed that Punjab region has highest mean grain yield followed by Azad Jammu & Kashmir (AJK). Regional differences in genetic diversity of maize germplasm were evident; AJK and Punjab possessed comparatively high genetic differences for various traits. Differences across the region genetic variability showed that various erosion accelerating forces worked differently in different regions. Chronological studies showed that grain yield had been improving in Pakistan since 1980s. Recent chronological period (2008-2016) has highest grain yield relative to earlier periods. Genetic diversity among available maize germplasm did not continuously reduce during last 36 years. In the earlier years diversity showed inclined followed by declining trend. Highest genetic diversity was observed in 1980-1984. Again there was boost in diversity during 1991-2000 followed by continuous decline till 2008-2016. It has been observed that addition of newly developed and better performing genotypes into informal seed system initially increased the diversity followed by substitution of landraces which led to genetic erosion in Pakistan. Genetic erosion in maize at regional and chronological levels in Pakistan is provoking need for conservation of genetic resources to avoid genetic vulnerability and depletion.
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