Rainfed Lowland Research Articles

Rice Yield and Grain Quality under Fluctuating Soil Moisture Stress

In rainfed lowlands and water-saving cultivation systems, rice plants are often exposed to soil moisture fluctuation (SMF). Improving yield as well as grain quality is the main target for breeding under water-stressed environments. This study investigated the effects of different water treatment on yield, growth parameters, and grain quality under field conditions in Japan for 2 years. Two rice genotypes, Nipponbare (japonica) and G3-3 (derived from Nipponbare and KDML105, indica), were grown under continuous waterlogging (CWL) and SMF conditions. As the grain quality characteristics, grain appearance, dimension, and taste parameters were evaluated as well as yield and yield components. SMF reduced the yield, and G3-3 showed a higher yield than Nipponbare under SMF, which was attributed to the higher number of spikelets per panicle. G3-3 showed a better taste score (mark) with lower protein and amylose contents compared to Nipponbare. However, G3-3 had a higher percentage of broken grains, indicating a trade-off in grain quality traits. Non-structural carbohydrate dynamics may be involved as one of the grain quality characteristics. G3-3 demonstrated a superior yield under SMF conditions and have potential to show superior grain quality, indicating that the introgressed segments of G3-3 may be responsible for the grain quality traits associated with root plasticity.

Nutrient Assessment of Rain-Fed Lowland and Upland Rice Production Systems in Okigwe, South-Eastern Nigeria

Nutrient Assessment of Rain-Fed Lowland and Upland Rice Production Systems in Okigwe, South-Eastern Nigeria

Old Foe, New Host: Epidemiology, Genetic Diversity, and Pathogenic Characterization of Maize Streak Virus in Rice Fields from Burkina Faso

Rice is of critical significance regarding food security worldwide, including in Africa. Only two viruses impacting rice production in Africa have been deeply investigated for decades: the rice yellow mottle virus ( Solemoviridae) and the rice stripe necrosis virus ( Benyviridae). Using viral metagenomics, we aimed at broadening knowledge on interacting communities associated with plants in rice landscapes and exploring the diversity and epidemiological status of viruses circulating in rice fields from Burkina Faso. We performed an epidemiological survey in this country between 2016 and 2019 involving 57 small farmers’ rice fields under two production systems: rainfed lowlands and irrigated areas. More than 2,700 rice samples were collected without regard to disease symptoms following a regular scheme. Wild and cultivated Poaceae (maize and sugarcane) growing in nearby rice fields were also collected. Unexpectedly, metagenomics detected maize streak virus (MSV) ( Geminiviridae) in analyzed rice samples. Further molecular analyses using rolling circle amplification-polymerase chain reaction showed that MSV was widely distributed and highly prevalent in both rainfed lowlands and irrigated rice areas. MSV-A and MSV-G strains were identified. MSV-G, exclusively identified thus far in wild grasses, was the most prevalent strain, whereas MSV-A, known to cause severe symptoms in maize, was sporadically identified. Using infectious clones in experimental conditions, we confirmed the pathogenicity of both MSV strains in rice. Thus, in addition to contributing to the epidemiological surveillance of rice production in Africa, our results illuminate new epidemiological and pathogenic aspects of one of the most studied plant viruses with significant economic consequences in Africa. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

On-Farm Assessment of the System of Rice Intensification (SRI) Under Rainfed Lowland Fields of Southern Cambodia

On-Farm Assessment of the System of Rice Intensification (SRI) Under Rainfed Lowland Fields of Southern Cambodia

Actinomycete inoculant improves the growth and yield of rainfed lowland and upland rice under field conditions

This study aimed to assess the effectiveness of actinomycete inoculant in enhancing the growth and yield of rainfed lowland and upland rice across wet and dry seasons in real field conditions. This field assessment took place at four sites, comprising two rainfed lowland and two rainfed upland ecosystems, over two cropping seasons (dry and wet seasons). The experiments involved testing both soil-based and carbonized rice hull (CRH) inoculants. Actinomycetes were found to be effectively carried by CRH and soil, and evidence from field studies in rainfed lowland and upland conditions showed that the actinomycete inoculant significantly improved rice production even under stressful environmental conditions. Regarding plant height, root depth, and tiller number, the inoculated treatments outperformed both the control and the full fertilization rates. Rice yield significantly increased with the application of actinomycete inoculum in both lowland and upland experiments. Inoculation alone led to substantial improvements, with yield increases of up to 48% in Lowland Site 1, 50% in Lowland Site 2, 78% in Upland Site 1, and 43% in Upland Site 2. Similarly, growth was enhanced by inoculation alone, reaching up to 50% in Lowland Site 1, 75% in Lowland Site 2, 24% in Upland Site 1, and 26% in Upland Site 2. When added to the full rate of fertilization, the inoculant significantly boosted yield by up to 16% in Lowland Site 1, 82% in Upland Site 1, and 40% in Upland Site 2. Additionally, growth substantially improved with inoculation in conjunction with the full rate of fertilization, reaching as much as 50% in lowland site 1, and 24% in upland site 1. Actinomycete inoculant proves to be a valuable alternative and addition to agricultural fertilizer management, as it was found to significantly increase growth and yield even in adverse weather conditions.

Specialty Rice (Oryza sativa L.) with High and Stable Grain Yield under Rainfed Lowland Conditions

This study aimed to identify superior genotypes of specialty rice (SR) with comparable or higher grain yield than the drought-tolerant check variety under rainfed and controlled-drought conditions. A total of 17 SR varieties (six aromatic, six pigmented, five glutinous) and a drought-tolerant check variety with ordinary grain quality were evaluated under rainfed lowland and controlled-drought conditions from 2019 to 2021 at Central Luzon State University in the Philippines. Among the SR varieties, aromatic NSIC Rc344, pigmented Black rice, and glutinous NSIC Rc15 had comparable or higher grain yield than the drought-tolerant check variety under both rainfed and controlled-drought conditions. These selected genotypes were classified as the highest yielding, with a more stable yield than the drought-tolerant check variety across the hydrological conditions based on the BLUPs productivity and stability test and drought tolerance indices. The selected SR varieties had a greater panicle number (NSIC Rc344), more grains per panicle (NSIC Rc15), and a higher 1000-grain weight and harvest index (Black rice). In comparison to a higher yield but with a higher market price due to the superior grain quality of the identified SR than the drought-tolerant check variety, the net income in rainfed lowland conditions significantly increased by 69–108%. These results suggest that planting good-performing SR in rainfed lowlands can increase profitability in this ecosystem due to the higher market price compared to ordinary drought-tolerant varieties.

Seasonal Changes in Zooplankton Population in Rainfed Rice-fish System

Integration of aquaculture in vast rainfed waterlogged lowlands can be an acceptable option for improvement of farm productivity and income in the country, particularly in the easter India. An adaptable technology on rice-fish, prawn, vegetable, fruits and other crops diversified farming system called Rice-fish System· has been developed at Central Rice Research Institute, Cuttack for waterlogged rainfed lowlands (Sinhababu and Venkateswarlu, 1995). Studies on the food and feeding habit of fish in this system is an important aspect for optimizing the fish productivity. Some information is available on the plankton profile of the irrigated rice field mainly (Saha and Ramakrishna, 1962; Li and Pan, 1992) and deep water ecology (Das et al., 1991) and also in shallow rainfed rice-fish seed system (Sinhababu et al., 1992), but not in the rice-fish system. We studied the seasonal changes in the zooplankton population in the system.

Dynamics ofthe rice yellow mottle disease inwestern Burkina Faso: Epidemic monitoring, spatio-temporal variation ofviral diversity, andpathogenicity ina disease hotspot.

The rice yellow mottle virus (RYMV) is a model in plant virus molecular epidemiology, with the reconstruction of historical introduction routes at the scale of the African continent. However, information on patterns of viral prevalence and viral diversity over multiple years at a local scale remains scarce, in spite of potential implications for crop protection. Here, we describe a 5-year (2015-9) monitoring of RYMV prevalence in six sites from western Burkina Faso (geographic areas of Bama, Banzon, and Karfiguela). It confirmed one irrigated site as a disease hotspot and also found one rainfed lowland (RL) site with occasional high prevalence levels. Within the studied fields, a pattern of disease aggregation was evidenced at a 5-m distance, as expected for a mechanically transmitted virus. Next, we monitored RYMV genetic diversity in the irrigated disease hotspot site, revealing a high viral diversity, with the current coexistence of various distinct genetic groups at the site scale (ca. 520 ha) and also within various specific fields (25 m side). One genetic lineage, named S1bzn, is the most recently emerged group and increased in frequency over the studied period (from 20 per cent or less in 2015-6 to more than 65 per cent in 2019). Its genome results from a recombination between two other lineages (S1wa and S1ca). Finally, experimental work revealed that three rice varieties commonly cultivated in Burkina Faso were not different in terms of resistance level, and we also found no significant effect of RYMV genetic groups on symptom expression and viral load. We found, however, that infection outcome depended on the specific RYMV isolate, with two isolates from the lineage S1bzn accumulating at the highest level at early infections. Overall, this study documents a case of high viral prevalence, high viral diversity, and co-occurrence of divergent genetic lineages at a small geographic scale. A recently emerged lineage, which comprises viral isolates inducing severe symptoms and high accumulation under controlled conditions, could be recently rising through natural selection. Following up the monitoring of RYMV diversity is required to confirm this trend and further understand the factors driving the local maintenance of viral diversity.

Performance of Six Generations on Two Rice Crosses under Submergence Stress and Non-stress Conditions

Submergence tolerance has long been regarded as an important breeding objective for rain-fed lowland and deep water rice area. Despite this recognition, there has been limited success in developing rice with improved submergence tolerance in Africa. The present research was aimed at assessing performance of crosses under submergence stressed and non-stressed conditions in Nigeria. Six generations of the crosses were evaluated under optimum and submerged conditions in a complete randomized block design with three replications. Submergence screening was performed in controlled conditions that allowed flooding at a water depth of 1.0 meter for a period of 14 days. The results revealed that significant difference among the generations of the two crosses evaluated. The observed survival rate (%) in Cross I of the generations ranged between 0.00% - 100% while in Cross II, it ranged between 0.00% and 95.24%. The Phenotypic Coefficients of Variation (PCV) and the Genotypic Coefficient of Variation (GCV) for 100 grain weight were moderate to high under the two conditions. Low to moderate PCV and GCV coefficients of variation were observed for the grain width and grain length under both conditions in the two crosses. High heritability (0.96% respectively) and high genetic advance as percentage of mean were recorded for the grain yield and grain weight in the two crosses. The variability observed among the generations was optimum however, advancement of the segregating generations coupled with adequate selection criteria could lead to identification of superior and stable genotypes for farmers’ use.

Effects of Sowing Methods on Paddy Rice Yields and Milled Rice Quality in Rainfed Lowland Rice in Wet Savannah, Togo

Identifying the socio-economic constraints of seeding technologies uptake and analyzing the yields, milled quality and growers’ income under various seeding methods are a strategy for sustainable rainfed lowland rice. A survey and an on-farm experiment were carried out at five locations with a random sample of 50 farmers grouped in five of the fourteen partner cooperatives of ESOP-Pagouda. The survey focused on socio-economic data collection. The experiment, replicated at five locations, involved three treatments: broadcast seeding, direct seeding, and transplanting. The paddy rice yields and milled rice quality were analyzed using R software version 4.1.3, and arithmetic means discriminated at the 5% by the Duncan test. The profitability indicators, such as the Gross Margin (GM) and the Benefit/Cost Ratio (BCR), were calculated. The results showed that 14% of farmers adopted rice transplanting method. The transplanting method increased rice yield (3.3 t/ha) compared to direct seeding (2.8 t/ha) and broadcast seeding (2.2 t/ha). The milled long grain rate (56%) was significantly higher than those under both seeding methods. Additionally, the transplanting method improved the gross margin (1,146 $USD/ha) compared to 663 $USD/ha and 431 $USD/ha for direct and broadcast seeding, respectively. The benefit/cost ratio 1.5 for transplanting was almost double from that of both seeding methods. Despite its high demand for labor and agricultural inputs, the transplanting method provided the highest paddy rice yields and milled rice quality to improve farmers’ income.

Opportunities beyond CO2 for climate mitigation

Opportunities beyond CO2 for climate mitigation

Agronomic Evaluation of Alternative Lowland Rice Varieties for Farmers in Uganda; A Case of Aromatic Rice

Rice has recently become an important crop for tackling food insecurity and poverty in Uganda. Over three-quarters of the country's local rice production occurs in irrigated and rain-fed lowlands in eastern and northern Uganda. However, breeding programs and seed systems have only partially met farmers' expectations for new lowland rice varieties and seeds recently, so farmers are sticking with old varieties. However, a new high-yielding, early-maturing, and most importantly, aromatic variety, NARORICE-1, released in 2019, seems to offer a new ray of hope for lowland rice farmers. This study compared the agronomic performance of NARORICE-1 and two promising KAFACI lines to a popular farmer's variety, WITA-9, in central, eastern, and northern Uganda. These varieties were evaluated for growth and yield response to higher seedling counts per hill when transplanted. Doho was the most productive location with an average rice yield of 6.1 t ha–1, significantly higher than NaCRRI and Olweny with 3.9 and 3.7 t ha–1, respectively. The yield performance of NARORICE-1 was comparable to that of the popular farmer's variety WITA-9. Increasing the number of seedlings per hill from three to seven during transplanting had no clear effect on the paddy yield of NARORICE-1. Besides higher yield potential, NARORICE-1's other additional beneficial traits such as aroma, shorter growing time, and higher milling efficiency have made it one of the growers' favorites.

Seizing opportunity towards sustainable rice cultivation in sub-Saharan Africa

Increasing rice production on a sustainable basis is a major challenge to research for development in sub-Saharan Africa. However, apart from yield, little efforts have been made to benchmark related performance indicators (PIs) including net profit, labor productivity, and nitrogen and phosphorus use efficiencies (NUE and PUE). The objectives of this study are to (i) assess these PIs and their determinants, and (ii) identify areas needed to improve them. Data were collected from 2,060 farmers in irrigated lowland (IL), rainfed lowland (RL), and rainfed upland (RU) rice production systems across two agroecological zones (semi-arid and subhumid) in the 2018/19 wet season at 18 sites in Burkina Faso, Ghana, Nigeria, Senegal, and Tanzania. Average yields were 4,952, 2,988, and 1,816 kg ha −1 in IL, RL, and RU. Higher yield was associated with higher profit. Labor productivity was 55 kg day −1 in IL, 75 kg day −1 in RL, and 49 kg day −1 in RU. Labor productivity was generally low because of limited use of agricultural equipment. NUE and PUE differed across production systems: 17%, 42%, and 49% of farmers had below desirable NUE (<40 kg grain kg −1 N) in IL, RL, and RU. Meanwhile, 62%, 44%, and 34% of farmers had above desirable PUE (100–250 kg grain kg P −1 ) in IL, RL, and RU, indicating a need to increase P application to avoid soil P mining. Cluster analysis of PIs identified four groups across 24 site–production system combinations. The low-performing group had larger field size, lower values for five PIs, and poorer crop management practices. These results suggest opportunities for improving rice productivity in low-performing groups through introduction of integrated crop management options, including improved crop and nutrient management together with labor-saving technologies such as mechanization.

Closing rice yield gaps in Africa requires integration of good agricultural practices

Despite decades of international research and development efforts focusing on increased rice production in Africa, there is large yield gap, and the local production still needs to be complemented by rice imports to meet consumption demands. This paper aims to provide an overview of published research findings on rice yield gaps and the effects of ‘good agricultural practices’ (GAPs) on rice yield and nutrient use efficiency. The majority of previous studies were from irrigated lowlands, and quantified rice yield gaps as farmer-based (difference between ‘actual yield’ and ‘best farmers’ yield’) and model-based yield gaps (difference between ‘actual yield’ and ‘potential yield for irrigated and water-limited potential yield for rainfed rice’). The mean farmer- and model-based yield gaps were 3.1 and 5.0 t ha–1 for irrigated lowland (IL); 3.1 and 7.7 t ha–1 for rainfed lowland (RL); 2.0 and 6.0 t ha–1 for rainfed upland (RU), respectively in Africa. An analysis of studies from literature on GAPs in Africa revealed that most studies (64 %) were from IL and a wide range of yield increases following individual components of GAPs across environments. A median yield increase of 1.0 t ha–1 was achieved with improved water conservation practices in IL, whereas improved weed management increased yields by 0.7 t ha–1, mainly in IL compared to farmers’ practices. Application of inorganic fertilizers and/or organic amendments increased the yield by 0.8–1.2 t ha–1 across the environments. Integration of GAPs increased the median yield by 2.1 and 1.5 t ha–1 in IL and RL, respectively. The calculated agronomic efficiency of N, P and K from fertilizer experiments were within the desirable levels mainly in the IL and RL environments and comparable to the values from similar environments in Asia. For instance, the agronomic efficiency of N was 21, 13 and 12 kg kg–1, respectively for IL, RL and RU in Africa. Although rice yield gaps in Africa can be substantially reduced by introduction of integrated GAPs to farmers, there is large difference between model-based yield gaps and yield gain obtained by integrated GAPs. Further efforts are needed to identify factors causing this difference. We recommend a research and development focus on rainfed lowland rice systems, which have the largest model-based yield gaps by partially converting them to irrigated systems, and on improving nutrient use efficiencies and closing nutrient cycles.

Competition between Rice and Weedy Rice under Different Water Regimes

The rainfed lowland (RFL) rice ecosystem is prone to drought stress and high weed infestation, including weedy rice (WR), which often negatively affects the yield. This study examined the competitive ability of rice and WR under mixed culture and drought stress. Two rice genotypes (drought-susceptible IR64 and drought-tolerant INL73) and a WR were grown in root boxes with soil under mono (rice or WR only) or mixed (rice/WR) cultures and subjected to either continuously waterlogged (CWL) or progressive drought (PDR) conditions during the early vegetative stage. Under PDR, SDW in all planting cultures was reduced relative to their CWL counterparts. The WR in mixed culture had higher SDW than its monoculture counterpart, regardless of water treatments. SDW in mixed cultures under PDR was not affected in IR64, reduced in INL73, and increased in WR relative to their monocultures. Under PDR, water use (WU) was higher in INL73/ WR than in IR64/WR mixed culture. Between two mixed cultures, WR mixed with INL73 had higher SDW than when mixed with IR64. The differences in stomatal conductance between INL73 and WR under mixed culture were attributed to the greater increase in total lateral root length of the latter than the former genotype under PDR. Overall, the results showed that WR had greater competitive ability than rice under mixed cultures, especially with a drought-tolerant rice variety. This calls for careful planning of cultivar adoption in rainfed systems where WR is a problem.

Scenario on Environmental Management to Reduce Green House Gas Emission Due To Low Land Rice Cultivation under Paddy Soils

As an important staple food crop rice production needs to be increased by 40% by the end of the 2030s to meet the increasing demand for food due to the expanding population. In this regard countries like Ethiopia having reasonable potential of rice production in various areas, mainly in rainfed lowland, upland and irrigated ecosystems are the major targets. But such Agricultural activities contribute to approximately 18.4% of to the present concentrations of GHGs emission followed by energy sector that are considered as one of the major sources of emissions however, this warming potential is a cumulative effect of 100 years horizon. CH 4 gas is produced under flooded or anaerobic soil conditions by the process of methanogenesis while N 2 O gas is produced through nitrification and denitrification processes. Consequently predicting the dynamic changes in emission of GHGs and rice yield in paddy fields and keeping the possible solution should be considered. From the scenarios of rice and green house gas emissions water managements on paddy soils as well as organic and inorganic fertilizations under plenty mass production of rice on paddy soils are top most considerable’s. Therefore conducting researches to fills the gap by determining the effect of nutrient and water management on rice yield and greenhouse gas emission should be developed and in lined with the mass production for the future. Keywords : Paddy Soils; Fertilization; Water Management; Green house gases DOI: 10.7176/JEES/12-4-01 Publication date: April 30 th 2022

Assessment of critical period for weeding and yield loss in direct seeded rice (Oryza sativa)

A field experiment was conducted at research farm of Regional Rainfed Lowland Rice Research Station, ICARNational Rice Research Institute, Gerua, Assam during two consecutive boro seasons of 2014–15 and 2015–16 to assess yield losses in direct seeded rice (DSR) under weeding times. There were two DSR establishment techniques (dry and sprouted seeding) in main plots and four weeding times (15, 30, 45 and 60 DAS) in sub plots. It was found that Scirpus juncoides, Echinochloa colona, Cyperus difformis, Cyperus iria, Monochoria vaginalis and Ludwigia octovalvis were the dominant weed species in shallow lowlands. DSR establishment techniques had non-significant effect on weed characteristics as well as growth, yield attributes and productivity of rice. Weed density of individual weed group and dry matter were significantly influenced by weeding times. Weeding at 15 DAS resulted in significantly low weed density and biomass as compared to weeding at 45 and 60 DAS. Growth and yield attributes, viz. plant height, panicles/m2, filled grains/panicle and fertility percentage were significantly higher and subsequently resulted in higher grain and straw yield under early weeding at 15 DAS. The highest grain yield losses due to weeds were calculated with weeding at 60 DAS (20.4%) followed by 45 DAS (15.8%) in DSR. Thus, early weeding in DSR plays an important role to obtain higher productivity of rice and minimise yield loss due to weeds.

Effect of Seed Rate and Row Spacing on Yield and Yield Component of Rainfed Lowland Rice Variety (Ediget) at Assosa, Western Ethiopia

Rice is one the newly introduced crop in western Ethiopia (Assosa). However, the yield is far below its genetic potential. Lack of proper management practice on seed rates and row spacing are one of the problems limiting. Field experiment was conducted to investigate the effect of seed rate and row spacing on yield and its traits of lowland rice The treatment consisted of seven levels of seed rate (40, 60, 80, 100, 120, 140, and 160 kg ha^-1) and four levels of row spacing (15, 20, 25, 30cm). The experiment was laid out as a Randomized Complete Block Design in a factorial arrangement and replicated three times. From the analysis of variance, all the parameters except filled grain were not significantly affected by seed rate and row spacing. The maximum plant height (90.38cm) was observed at seed rate of 40 kg ha^-1 and the lowest was observed at seed rate of 160 kg ha^-1. The highest panicle length (16.77cm), tiller per plant (3.37) and filled grain (86.93) was observed at seed rate of 40 kg ha^-1. Filled grain was highly significant and the highest filled grain was observed at 40 kg ha^-1 (86.93) and at 15cm spacing (70.07). The highest grain yield (3.93 t ha^-1) was obtained at a seed rate of 60 kg ha^-1 and 20cm row spacing. The economic analysis indicated that a seed rate of 60 kg ha^-1 and row spacing of 20cm is the most profitable treatment with mean net benefit of 86,110 Birrha^-1. Therefore it can be concluded that a seed rate of 60 kg/ha and row spacing of 20cm is preferable and recommended for rain fed lowland rice production areas in the study areas.

Spatiotemporal Survey of Multiple Rice Diseases in Irrigated Areas Compared to Rainfed Lowlands in the Western Burkina Faso.

Multiple constraints affect rice yields in West Africa. Among these constraints are viral, bacterial, and fungal pathogens. We aimed to describe the spatiotemporal patterns of occurrence and incidence of multiple rice diseases in farmers' fields in contrasting rice growing systems in the western Burkina Faso. For this purpose, we selected a set of three pairs of sites, each comprising an irrigated area and a neighboring rainfed lowland, and studied them over four consecutive years. We first performed interviews with the rice farmers to better characterize the management practices at the different sites. This study revealed that the transplanting of rice and the possibility of growing rice twice a year are restricted to irrigated areas, while other practices, such as the use of registered rice cultivars, fertilization, and pesticides, are not specific but differ between the two rice growing systems. Then, we performed symptom observations at these study sites to monitor the following four diseases: yellow mottle disease, Bacterial Leaf Streak (BLS), rice leaf blast, and brown spot. The infection rates were found to be higher in irrigated areas than in rainfed lowlands, both when analyzing all observed symptoms together (any of the four diseases) and when specifically considering each of the two diseases: BLS and rice leaf blast. Brown spot was particularly prevalent in all six study sites, while yellow mottle disease was particularly structured geographically. Various diseases were frequently found together in the same field (co-occurrence) or even on the same plant (coinfection), especially in irrigated areas.

Agro-morphological and Genotypic Diversity among Rice Germplasms under Rainfed Lowland Condition

The present study was performed in a randomized complete block design with three replications to identify higher yielding genotypes and putative traits for grain yield improvement under a rainfed environment. Genotypes recorded highly significant variation for most of the observed agro- morphological traits except the number of effective tillers/m2. IR102774-31-21-2-4-7 (5.40 t/ha) followed by IR99739: 2-1-1-2-1 (5.22 t/ha), and IR103587-23-2-1-B (5.05 t/ha) respectively were the higher grain yielders. These high yielders were among the sets of early flowering (85-96 days) and maturing (120-130 days) genotypes. Plant height (PHT- 86.62% and 25.69%), harvest index (HI-87.17% and 44.66%), and thousand-grain weight (TGW- 71.06% and 30.05%) recorded high heritability values coupled with higher genetic advance as a percentage of the mean (GAM). IR102774-31-21-2-4-7 produced superior agro-morphological character for several traits like grain yield, thousand-grain weight, biological yield, plant height, and days to flowering and maturity. Plant height, biological yield, harvest index, days to flowering, and maturity were highly associated with grain yield and had medium to high heritability and GAM values. Therefore, these traits might be of importance for selection in grain yield improvement of rice under rainfed lowland conditions.