Abstract
Field experiments were conducted at the Rivers State University Teaching and Research Farm Nkpolu, Port Harcourt, during the 2019 planting season under rainfed condition and complimented by irrigation in two different planting dates to access the genetic variability and heritability in yield and yield components of twenty-five rice varieties. The experiments were laid out in a randomized complete block design with three replications. Data were collected on eleven yield and yield components. Results from the analysis of variance indicated significant differences (P < 0.01 < 0.05) among the varieties for all parameters except plant height and tiller number in planting date one. Combined analysis of variance across planting dates showed that there was significant variation (P < 0.01) among the rice varieties for all parameters evaluated. The varietal mean performance for phenological parameters showed significant differences (P < 0.05) for all parameters except tiller number in planting date one. Variability evaluation of varieties for yield parameters showed significant differences (P < 0.05) for all parameters evaluated except for 100-grain weight in planting date two. The pooled mean values of the varieties differed significantly (P < 0.05) for all yield parameters evaluated. The highest grain yield per stand was recorded in UPIA 2 with 7.41 g/stand, and was significantly different from FARO 67 with the least (1.70 g/stand). The estimate of variance components showed that phenotypic variance (Vp) and phenotypic coefficient of variation (PVC) were higher than their corresponding genotypic variance (Vg) and genotypic coefficient of variation (GCV) for all the parameters studied. Heritability estimates in broad sense were found to be moderate for majority of the parameters, except leaf area (68.12%), panicle number (63.41%), spikelet fertility (50.23%) and grain yield per stand (55.87%) that had high heritability estimates and tiller number (15.93%) which had a low estimate. However, only leaf area, panicle number and grain yield per stand had high heritability estimates which were accompanied by high genetic advance. There was considerable variation among the 25 rice varieties evaluated. UPIA 2 and FARO 44 had the best agronomic performance. However, UPN 324, UPN 228, FARO 61 and 66 could be selected for onward improvement programme. Keynote: Grain yield, heritability, Oryza sativa , variation, yield components DOI: 10.7176/ALST/86-04 Publication date: March 31 st 2021
Highlights
Rice belongs to the genus Oryzae which contains about 20 diverse species including O. glaberrima, O. sativa, O. perennis, O.nivara, etc. (Efisue et al, 2008)
Evaluation of variability and yield and yield components The mean squares obtained from the analysis of variance revealed that genotypic effect was significant (P ≤ 0.01) and (P ≤ 0.05) for all parameters evaluated in the two different planting dates except plant height and tiller number in planting date 1
Significant planting date effect was observed for leaf area, days to 50% flowering, tiller number, panicle number, panicle length, spikelet fertility, number of grains per panicle and grain yield per stand
Summary
Rice belongs to the genus Oryzae which contains about 20 diverse species including O. glaberrima, O. sativa, O. perennis, O.nivara, etc. (Efisue et al, 2008). Rice varietal improvement has come a long way in Nigeria over the past decades with evidences of success in the development of early maturing varieties having higher grain yield, better grain quality, high milling recovery and nutrient content much more than what was obtained in the local unimproved varieties, as is evident in the improved FARO lines (Oluwaseyi et al, 2016). These improvement programs are always targeted towards an area of need in a particular environment or to tackle a prevailing problem in a crop of interest. In as much as we have a lot of improved varieties, there is the need to evaluate the landraces and select for those traits that made them survivors in our environment and to collate germplasm suitable for peculiar agroecological zone for onward breeding programme because the improved varieties are not holistic in terms of all-important traits
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