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 \u003c 0.01 \u003c 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 \u003c 0.01) among the rice varieties for all parameters evaluated. The varietal mean performance for phenological parameters showed significant differences (P \u003c 0.05) for all parameters except tiller number in planting date one. Variability evaluation of varieties for yield parameters showed significant differences (P \u003c 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 \u003c 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

The objective of this study was to explore the heterosis of partial interspecific hybrids between African rice (Oryza glaberrima Steud.) and Asian rice (Oryza sativa L.) and its correlation with genetic distance. Sixty-nine rice accessions including 57 introgression lines (ILs) were tested for population structure and genetic distance. Forty-nine crosses between ILs and a test variety, Shengtai1 (ST1), were evaluated for midparent heterosis of nine agronomic traits. Population structure, genetic distance, and the proportion of O. glaberrima genome (PGG) of ILs and heterosis of the test crosses were estimated and analyzed. The PGG of the ILs ranged from 1.22 to 49.71%, with an average of 15.29%. The genetic distance between parents of the tested crosses was positively correlated to the PGG of ILs (r = .95, P < .01). Positive heterosis was scored on plant height (12.23%), panicles per plant (19.97%), panicle length (10.37%), spikelets per panicle (24.06%), thousand-grain weight (14.00%), length/width ratio of grain (0.03%), and grain yield per plant (60.77%) of the partial interspecific hybrids. Although the introgression of more African genomic genes could effectively increase the genetic distance between ILs and the test variety that lead to positive heterosis for most agronomic traits, it could also increase the possibility of the occurrence of interspecific sterility that might decrease the seed setting rate and result in negative heterosis (-2.57%). These data indicated that the introgression of African rice genes into the genome of Asian rice could effectively broaden the genetic diversity, and the deployment of ILs as parents could be a potential way for exploiting interspecific heterosis in rice.

Rice is a stable food crop in Nigeria and greater percentage of the world.Rice is an important cereal crop of the world and nutritionally potential food crop.Iron plays a vital role in human life.Such as in production of red blood cells, transportation of oxygen around the body, strong immune system and a component structure of the human haemoglobin.It is also involved in the conversion of blood sugar to energy.The study screened some cultivars of Oryza sativa for their abilities to retain Iron (Fe), their response to Fe biofortification and their adaptabilities and tolerance capacities for Fe biofortification under saline condition.Five (5) cultivars of lowland rice namely; FARO 44, UPIA 3, FARO 52, FARO 57 and IWA 4 were used for this study.One hundred (100µg) of Fe from FeNH4.(SO4).12H2Owas applied through foliar application.The Fe increase available for human body use was comparatively higher in the fortified than unfortified treatment, especially those planted in the non saline treated soil.Under saline condition, the Fe increase in fortified FARO 44 was less than in the unfortified by approximately nine percent (9.29%).UPIA 3 was higher by 20.48%, FARO 52 higher by 14.43%, FARO 57 higher by 22.83% and IWA 4 was higher by 27.08%.In the non saline fortified, FARO 44 was higher than the unfortified by 71.9%, UPIA 3 by 20.26%, FARO 52 by 30.71%,FARO 57 was higher by 217.21% and IWA 4 increased by 6.95%.The study revealed that FARO 57 was more sensitive to salinity in Fe biofortification and UPIA 3 was more suitable for Fe biofortification under saline condition among the cultivars used for the study.UPIA 3 is the best because it was more stable in both saline and non saline, fortified and unfortified conditions, high yielding and was not infected or being susceptible to any disease.The study also showed that FARO 57 in non saline soil had the best ability to retain Fe in iron biofortification.But unfortunately, FARO 57 has lodging mechanism that affected its yield.To eliminate micronutrients malnutrition and improve food security, there should be integration of multidiscipline and biofortification employed as a tool to produce cultivars of high yielding and rich in essential nutrients.

This study was designed to identify level of awareness/knowledge of rice farmers in South-eastern Nigeria about climate-change; identify adverse effects of climate-variability and change on rice production and determine adaptation strategies used by small holder rice farmers within study area. Multistage purposive and stratified sampling technique was used for the sample selection. Information from 360 respondents was got using Rapid Rural Appraisal (RRA), Focus Group Discussions (FGD), and actual survey with questionnaires. Results showed that the rice farmers were aware of weather changes with grave effects on their rice farms. They reported changes in rainfall regime, intense sunshine, high temperature etc. Of special interest among the adaptation strategies by farmers are the use of inorganic fertilizers, improved rice varieties, cultivation of early maturing varieties, and proper preservation of rice seeds. This study recommends urgent measures to improve resilience of smallholder farmers in rural communities to enable them better adapt to climate-change. This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License .

The coastal region of Nigeria has abundant water naturally good for rice production, which is untapped due to oil exploration. The study was conducted to access the relationship between grain yield (GY) and its components of twenty-six segregating lines for the coastal region of Southern Nigeria. The experiment was conducted at the University of Port Harcourt teaching and Research Institution of Faculty of Agriculture and replicated three times in a complete block design. Data was collected on yield components such as number of tillers per plant, leaf area index (LAI), total GY at maturity, and grain weight per panicle at maturity. About 8 lines had more tiller number than the general mean value (30) at maximum tillering stage of the rice crop, while lines with high effective tiller numbers were IRBW-180 (49) and IRBW-147 (48). GY significantly positively correlated with effective tiller number, grain weight per plant, number of grain per panicle and grain weight per panicle. The cluster analysis for genetic diversity revealed three major groupings (A, B and C). The genotypes in Group A posses the character of high grain weight and Group B posses characters for long panicle and high value of flag LAI (FLAI), which indicates broad leaf for light interception thus enhancing photosynthesis. In Group C, genotypes posses varying characters, however, high value of LAI and tall plant, which indicates tendency of good nutrient utilization. Soil in this region is saline and effect crop performance especially rice, these identified indexes will facility the breeding for this region.

Drought stress during the vegetative stage can cause irreversible damage to rice (Oryza sativa L.) plants, resulting in inadequate grain production. Morpho-physiological traits have been used as indirect measures of drought-stress tolerance in rice, but these traits are genotype and environment dependent. This study was therefore conducted to determine which morpho-physiological traits were associated with drought stress tolerance and to examine genotypic stability under different environmental conditions as potential genotype donors for drought tolerance breeding in rice. Sixteen genotypes, including seven Oryza glaberrima Steud, six interspecific (O. sativa x O. glaberrima) inbred genotypes, two improved O. sativa L. subspecies japonica genotypes, and a variety OS6 (drought-tolerant check) were evaluated for drought tolerance at the vegetative stage. Trials were conducted during the dry seasons of 2004 and 2005 at Samanko Research Station in Mali. A fully irrigated trial was included as a control in 2005. After sowing, overhead sprinkler irrigation was applied for 35 days, three times weekly. To induce stress, irrigation was withdrawn in the stressed experiments for 21 and 43 days in 2004 and 2005, respectively. Genotypes reacted differently to drought stress for the characters examined. Most of the genotypes examined under drought stress exhibited drought tolerance and avoidance mechanisms for most of the morpho-physiological characters under study. The GGE biplot revealed RAM163, WAB365-B-1-H1-HB, and WAB375-B-9-H3-2 to be stable genotypes under drought stress, which could be recommended for use as donor lines for the drought-stress improvement program.

We investigated the chemical nutrient composition of 15 selected indigenous and five of the newly introduced hybrid rice varieties in Ebonyi State, Nigeria. The rice cultivars were field-grown, processed, and analyzed for proximate and mineral composition. The results showed that cv. “Canada” had the highest ash content (2.0 %). High percentage carbohydrate was found in all the genotypes (51.5 86.9 %). Cv.“E4212” had the highest crude protein (7.94 %), while “Sipi” had the least (1.58 %). Cv.“E4197” had the least energy value of 262.94 J/Kg, while “Canada” had the highest value of 398.82 J/Kg. “Canada” had the highest fat content (3.5 %), while “Sipi” and “Faro14 (I)” both contained the least fat (0.5 %). “China” and “Mass (II)” similarly had the highest percentage of crude fibre (2.5 %), while “E4334”, “Faro 25 (II)” and “Mass (I)” all had the least value of 1.0 % for crude fibre. Cv.“E4197” had a very high moisture content of 9.6 % as against “E4212” which had the least moisture content of 5.0 %. In relation to mineral content, “Chinyereugo” was highest in calcium (0.13 %), “Faro1(I)” had the highest amount of Magnesium (0.26 %), “E4197” and “E4212” had the highest percentage of phosphorus (0.55 %),“E4197” and “E4212” had the highest concentration of potassium (0.23 %), while “Canada”, “Faro15 (II)” and “Chinyereugo” possessed the highest percentage of sodium (0.17 %). One of the newly introduced hybrid varieties “E4212” had relatively higher protein and mineral contents, but less fat content. “Sipi” variety has no special quality attributes over the other existing local rice varieties apart from the fact that it is among the varieties that contain relatively low fat percentage just as “Faro 14”. The “Faro” varieties showed good proximate and mineral composition values which consumers would desire. The high premium presently placed on “Mass” varieties is uncalled for, since it has got no special characteristics over most other varieties. Consumers and farmers should therefore be better informed on the choice of rice varieties based on their nutritional quality attributes.

The Choice of rice varieties by farmers and the rate at which farmers in Ebonyi state go for new rice varieties at the expense of indigenous varieties have become a source of worry to scientists. We assessed the agronomic characteris- tics of 15 selected indigenous and newly introduced hybrid rice varieties in Ebonyi State, Nigeria. The Rice cultivars were grown under the same conditions and screened for morpho-agronomic traits. Significant variation (P<0.05) was detected among the 20 rice varieties for all the traits evaluated. The results showed that plant height ranged between 144.01 cm in "Mass (I)" and 76.00 cm in "Chinyeugo". Cv. "E4197" had the highest value of 38±0.02 cm for panicle length and "Chin- yereugo" had the highest value of 6.3g ± 0.03 for panicle weight. Leaf area showed the highest value of 63.8cm 2 ± 0.01 in "Mass (I)". Flowering time ranged from 138 ± 0.1days in "Mass (I)" to 68 ± 0.04 days in "Chinyereugo" while "Mass (II)" and "E4077" took the shortest period of 14 days after flowering to mature. Cv. "Co-operative" had high number of seeds per panicle (139 ± 0.19). "Chinyereugo" had the highest value of 25.9g ±1.4 for 1000-grains weight. The grain of "E4314" was the longest (8.00 mm ± 0.89) of the varieties studied. The grains of "Awilo" had a grain width of 2.62mm ± 0.04, while "E4197" had the highest value for grain width of 4.1 mm. Farmers should, therefore, be critical in accepting new varieties that may not be comparably outstanding in a holistic sense, in order to preserve the integrity of the all-cherished indigenous rice varieties .

Drought is one of the major constraints for rice (Oryza sativa L.) production in the rainfed ecologies in Sub-Saharan Africa. The objectives of this study were to investigate the genetic effects of morpho-physiological traits controlling drought-stress tolerance. Five Oryza glaberrima genotypes, four interspecific inbred lines, two interspecific hybrids, and two O. sativa lines and their progenies from a North Carolina II mating design were evaluated at ICRISAT in Mali under drought and fully irrigated conditions in 8 x 8 lattice designs. Data were collected on morpho-physiological traits, such as plant height, leaf rolling and stress recovery ability. General combining ability (GCA) effects for females and males were significant for all traits. Female GCA and specific combining ability (SCA) effects were significant for tiller number, plant height, and specific leaf dry weight. Heritability estimates based on variance ratios ranged from 47% to 67% for plant height, leaf area, specific leaf dry weight, and SPAD (chlorophyll); these were not significant for tiller number, which was controlled by overdominance. Heritability estimates based on regression were significant and ranged from 22% to 72% for drought-tolerance scores and leaf rolling scores. Highly significant positive relationships were observed between F-3 and F-4 generations for drought tolerance and leaf-rolling scores in all the populations examined. Both additive and non-additive genetic affects were important in controlling morpho-physiological traits; hence breeding procedures that exploit both GCA and SCA should be considered to improve drought tolerance in this rice germplasm.

Drought is an important production constraint in rice (Oryza sativa L.) in Africa. A breeding approach is needed to improve traditional rice by introgression of new genes for drought tolerance and high yield at early generation to enhance production. This study was conducted to identify drought-tolerant progenies in early generations and to establish a relationship between drought tolerance and some morphological and physiological traits. Interspecific progenies were generated using North Carolina II mating design and were advanced to F3 and F4 generations. Progenies were evaluated in 8 × 8 and 9 × 9 simple-lattice designs under managed drought stress and fully irrigated conditions, respectively. Overhead sprinkler irrigation was applied till maximum tillering stage (35 d after sowing) and stopped in the stress experiment for 50 d to induce stress and resumed thereafter until maturity. Significant differences were detected among genotypes for drought tolerance, and tillering and flowering dates. Selection indices ranging from –42.74 to 20.70 were therefore used to rank the progenies. Drought stress delayed flowering and was more pronounced in early- than late-flowering progenies. High-tillering progenies had larger reduction in tiller number than low-tillering progenies under stress. Drought tolerance (little leaf drying), taller plants and less leaf rolling were significantly associated with rapid ability to recover at 3 d and 10 d after drought-stress relief. The putative traits identified could be used as indicators of drought stress tolerance in a breeding program.