Within variety flowering time variation leads to yield variation in Sri Lankan traditional rice “Sudu wee”

Abstract

Sri Lankan traditional rice is an important breeding resource for development of rice for ecological adaptation during the era of climate change. There are around 2000 accessions belonging to more than 500 varieties comprised of one to several accessions in each with wider morphological differences, flowering times and yield variations. Genetic identity of Sri Lankan traditional rice accessions belonging to each rice variety is not established at molecular level. Variety Sudu wee comprises of around 30 accessions at PGRC. Sudu wee could be useful in re-introduction programmes of traditional rice due to relatively shorter crop duration. The objective of the present study was to evaluate the diversity of 29 Sudu wee accessions from PGRC, based on days to flowering, (DF), 12 morphological and 2 physiological characters during non-inductive photoperiod season. DF varied from 62 to 106 days while accession 4193 did not flower during the experimental period of nearly 7 months. Leaf temperature at heading (LeT) and Leaf temperature difference at heading (LeTD), vegetative morphological characters and yield components varied among Sudu wee accessions. Seventy nine percent of total observed variation among accessions was explained through Principal Component Analysis. In the dendogram of accessions, 10 clusters were formed at the rescale distance of 5. Seed morphology indicated the genetic similarity among accessions while significantly different DF could be an indication of flowering time gene variation among similar genotypes. Increased DF reduced the grain yield increasing the vegetative growth among accessions of Sudu wee. Our results would be useful in future breeding for manipulating flowering time and yield within similar genetic backgrounds.

Morphological diversity of Sri Lankan traditional rice varieties “Pachchaperumal” and “Suduru samba”

“…Delayed flowering time increased the vegetative growth and reduced the grain size (Table 5). Similar observations were reported for Sulai, Sudu wee and Hondarawala varieties, where there were positive relationships between DF and vegetative growth characteristics, while negative relationships existed between DF and yield components (Rathnathunga et al 2013;Rathnathunga et al 2015;Rathnathunga et al 2016b;Rathnathunga et al 2016c). In contrast, relationship between DF and yield components of photoperiod responsive 43 Ma wee accessions of Sri Lankan traditional rice was positive under inductive short day season (Pushpakumari et al 2017).…”

“…Comparatively similar PCs were identified in studies of Sulai, Sudu wee and Hondarawala varieties, which suggested the fact that same character standards applied in all genetic diversity studies of Sir Lankan rice (Rathnathunga et al 2015;Rathnathunga et al 2016b;Rathnathunga et al 2016c) (Table 2). Pachchaperumal accessions of 8827, 3408, 3752, 5548, 5550, 5547 and 9047 of cluster one, 5546, 3946, 6834 and 5549 of cluster two, accession of 5383 of cluster three were grouped into…”

“…We have observed a wide flowering time variation among traditional rice Sulai (57-179 days), Sudu wee (62 to 200 days+) and Hondarawala (57 to 200 days+) accessions during late short day season in Sri Lanka in contrast to Pachchaperumal (60 -72 days) and Suduru samba (79 -99 days) (Rathnathunga et al 2015;Rathnathunga et al 2016b;Rathnathunga et al 2016c). The two varieties could be distinguishable due to variation in quantitative characters of DF, vegetative growth parameters and grain size, and qualitative character of pericarp colour.…”