Water extraction and root traits in Oryza sativa × Oryza glaberrima introgression lines under different soil moisture regimes

2013 ◽  
Vol 40 (1) ◽  
pp. 54 ◽  
Author(s):  
Abubakary A. Kijoji ◽  
Susan Nchimbi-Msolla ◽  
Zakaria L. Kanyeka ◽  
Stephen P. Klassen ◽  
Rachid Serraj ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Drought Stress ◽  
Water Uptake ◽  
Root Traits ◽  
Genetic Differences ◽  
Introgression Lines ◽  
Sub Saharan Africa ◽  
Future Research ◽  
Oryza Glaberrima ◽  
Soil Drying

Drought is a major constraint to rainfed rice production in some parts of sub Saharan Africa (SSA) because of irregular and low rainfall. Improving root water uptake during progressive soil drying could contribute to terminal drought stress resistance. Two lysimeter experiments were conducted using 200 introgression lines (ILs) derived from Oryza sativa L. × Oryza glaberrima Steud. crosses (IR64/RAM54 and IR64/RAM90) to characterise water uptake and root traits under progressive soil drying and to assess genetic differences among these lines in relation to drought stress. The lysimeter facility setup and protocols for simultaneous monitoring of water uptake rates and leaf area are described. Significant genetic variability for water uptake and root traits among the ILs was observed under drought stress. Water uptake in the drought stress treatments was correlated with root length density (RLD) and root dry matter (RDM) at lower soil depths. The highest RLD values at depth were observed among the RAM90 ILs and genetic differences were observed between RAM90 and RAM54 populations, implying that accession RAM90 could be used as a source for improving drought avoidance in lowland rice. The ILs with greater water uptake identified in this study will be used in future research for improving drought resistance of rice in SSA.

Linking root traits and grain yield for rainfed rice in sub-Saharan Africa: Response of Oryza sativa×Oryza glaberrima introgression lines under drought

2014 ◽  
Vol 165 ◽  
pp. 25-35 ◽  
Author(s):  
Abubakary A. Kijoji ◽  
Susan Nchimbi-Msolla ◽  
Zakaria L. Kanyeka ◽  
Rachid Serraj ◽  
Amelia Henry
Keyword(s):  
Oryza Sativa ◽  
Grain Yield ◽  
Root Traits ◽  
Introgression Lines ◽  
Sub Saharan Africa ◽  
Oryza Glaberrima ◽  
Rainfed Rice ◽  
Sub Saharan

scholarly journals Water uptake dynamics under progressive drought stress in diverse accessions of the OryzaSNP panel of rice (Oryza sativa)

2012 ◽  
Vol 39 (5) ◽  
pp. 402 ◽  
Author(s):  
Veeresh R. P. Gowda ◽  
Amelia Henry ◽  
Vincent Vadez ◽  
H. E. Shashidhar ◽  
Rachid Serraj
Keyword(s):  
Oryza Sativa ◽  
Drought Stress ◽  
Root Growth ◽  
Water Uptake ◽  
Root Length Density ◽  
Oryza Sativa L ◽  
Root Water Uptake ◽  
Snp Markers ◽  
Drought Response ◽  
Genotypic Differences

In addition to characterising root architecture, evaluating root water uptake ability is important for understanding drought response. A series of three lysimeter studies were conducted using the OryzaSNP panel, which consists of 20 diverse rice (Oryza sativa L.) genotypes. Large genotypic differences in drought response were observed in this genotype panel in terms of plant growth and water uptake. Total water uptake and daily water uptake rates in the drought-stress treatment were correlated with root length density, especially at depths below 30 cm. Patterns of water uptake among genotypes remained consistent throughout the stress treatments: genotypes that initially extracted more water were the same genotypes that extracted more water at the end of the study. These results suggest that response to drought by deep root growth, rather than a conservative soil water pattern, seems to be important for lowland rice. Genotypes in the O. sativa type aus group showed some of the greatest water uptake and root growth values. Since the OryzaSNP panel has been genotyped in detail with SNP markers, we expect that these results will be useful for understanding the genetics of rice root growth and function for water uptake in response to drought.

scholarly journals Water and Nitrogen (N) Use Efficiency of Upland Rice (Oryza sativa L. × Oryza glaberrima Steud) under Varying N Application Rates

Nitrogen ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 151-166
Author(s):  
Isaac Newton Alou ◽  
Michael van der Laan ◽  
John George Annandale ◽  
Joachim Martin Steyn
Keyword(s):  
Oryza Sativa ◽  
Grain Yield ◽  
Upland Rice ◽  
Oryza Sativa L ◽  
Rice Variety ◽  
N Uptake ◽  
Sub Saharan Africa ◽  
Oryza Glaberrima ◽  
Use Efficiency ◽  
N Rates

Upland rice (Oryza sativa L.) production systems in sub-Saharan Africa are faced with challenges of water stress and nitrogen (N) deficiency, which reduce grain yield, water use efficiency (WUE), and nitrogen use efficiency (NUE). The objective of the study was to determine the response of upland rice to N fertilizer rates under well-watered conditions and to clarify the relationships between WUE and NUE. Upland rice variety Nerica 10 was grown under well-watered conditions and varying N rates in 2014/2015 (Y1) and 2015/2016 (Y2) on the same field at the University of Pretoria’s Hatfield Experimental Farm, South Africa. Yields at harvest increased with increasing N rates, linearly in Y1, and following a quadratic trend in Y2. Mean grain yield was highest (4.5 t ha−1) at 120 kg N ha−1 and lowest (2.4 t ha−1) at 0 kg N ha−1. Agronomic NUE was lowest for 160 kg N ha−1 (11.7 kg kg−1 N), while WUE was highest for the 120 kg N ha−1 (7.58 ± 1.7 kg mm−1) and lowest for 0 kg N ha−1 (4.1 ± 0.9 kg mm−1). Findings revealed that at high N levels, compensative N uptake during tillering can reduce harvest index, WUE, and to a lesser extent, grain N concentration.

Assessment of rice (Oryza sativa L.) genotypes for drought stress tolerance using morpho-physiological indices as a screening technique

2020 ◽  
Vol 53 (1) ◽  
Author(s):  
Asma Asma ◽  
Iqbal Hussain ◽  
Muhammad Yasin Ashraf ◽  
Muhammad Arslan Ashraf ◽  
Rizwan Rasheed ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Drought Stress ◽  
Stress Tolerance ◽  
Oryza Sativa L ◽  
Screening Technique ◽  
Drought Stress Tolerance ◽  
Physiological Indices

scholarly journals Multispectral Remote Sensing of Wetlands in Semi-Arid and Arid Areas: A Review on Applications, Challenges and Possible Future Research Directions

2020 ◽  
Vol 12 (24) ◽  
pp. 4190
Author(s):  
Siyamthanda Gxokwe ◽  
Timothy Dube ◽  
Dominic Mazvimavi
Keyword(s):  
Remote Sensing ◽  
Arid Regions ◽  
Remote Sensing Data ◽  
Sub Saharan Africa ◽  
Future Research ◽  
Multispectral Imagery ◽  
Aquatic Life ◽  
Sensing Data ◽  
Spatial Coverage ◽  
Semi Arid

Wetlands are ranked as very diverse ecosystems, covering about 4–6% of the global land surface. They occupy the transition zones between aquatic and terrestrial environments, and share characteristics of both zones. Wetlands play critical roles in the hydrological cycle, sustaining livelihoods and aquatic life, and biodiversity. Poor management of wetlands results in the loss of critical ecosystems goods and services. Globally, wetlands are degrading at a fast rate due to global environmental change and anthropogenic activities. This requires holistic monitoring, assessment, and management of wetlands to prevent further degradation and losses. Remote-sensing data offer an opportunity to assess changes in the status of wetlands including their spatial coverage. So far, a number of studies have been conducted using remotely sensed data to assess and monitor wetland status in semi-arid and arid regions. A literature search shows a significant increase in the number of papers published during the 2000–2020 period, with most of these studies being in semi-arid regions in Australia and China, and few in the sub-Saharan Africa. This paper reviews progress made in the use of remote sensing in detecting and monitoring of the semi-arid and arid wetlands, and focuses particularly on new insights in detection and monitoring of wetlands using freely available multispectral sensors. The paper firstly describes important characteristics of wetlands in semi-arid and arid regions that require monitoring in order to improve their management. Secondly, the use of freely available multispectral imagery for compiling wetland inventories is reviewed. Thirdly, the challenges of using freely available multispectral imagery in mapping and monitoring wetlands dynamics like inundation, vegetation cover and extent, are examined. Lastly, algorithms for image classification as well as challenges associated with their uses and possible future research are summarised. However, there are concerns regarding whether the spatial and temporal resolutions of some of the remote-sensing data enable accurate monitoring of wetlands of varying sizes. Furthermore, it was noted that there were challenges associated with the both spatial and spectral resolutions of data used when mapping and monitoring wetlands. However, advancements in remote-sensing and data analytics provides new opportunities for further research on wetland monitoring and assessment across various scales.

scholarly journals Prevalence and determinants of chronic kidney disease in women with hypertensive disorders in pregnancy in Nigeria: a cohort study

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Salisu M. Ishaku ◽  
Timothy Olusegun Olanrewaju ◽  
Joyce L. Browne ◽  
Kerstin Klipstein-Grobusch ◽  
Gbenga A. Kayode ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Gestational Hypertension ◽  
Monitoring Program ◽  
Sub Saharan Africa ◽  
Future Research ◽  
Hypertensive Disorders ◽  
Hypertensive Disorders In Pregnancy ◽  
Sub Saharan ◽  
In Pregnancy

Abstract Background Worldwide, hypertensive disorders in pregnancy (HDPs) complicate between 5 and 10% of pregnancies. Sub-Saharan Africa (SSA) is disproportionately affected by a high burden of HDPs and chronic kidney disease (CKD). Despite mounting evidence associating HDPs with the development of CKD, data from SSA are scarce. Methods Women with HDPs (n = 410) and normotensive women (n = 78) were recruited at delivery and prospectively followed-up at 9 weeks, 6 months and 1 year postpartum. Serum creatinine was measured at all time points and the estimated glomerular filtration rates (eGFR) using CKD-Epidemiology equation determined. CKD was defined as decreased eGFR< 60 mL/min/1.73m2 lasting for ≥ 3 months. Prevalence of CKD at 6 months and 1 year after delivery was estimated. Logistic regression analyses were conducted to evaluate risk factors for CKD at 6 months and 1 year postpartum. Results Within 24 h of delivery, 9 weeks, and 6 months postpartum, women with HDPs were more likely to have a decreased eGFR compared to normotensive women (12, 5.7, 4.3% versus 0, 2 and 2.4%, respectively). The prevalence of CKD in HDPs at 6 months and 1 year postpartum was 6.1 and 7.6%, respectively, as opposed to zero prevalence in the normotensive women for the corresponding periods. Proportions of decreased eGFR varied with HDP sub-types and intervening postpartum time since delivery, with pre-eclampsia/eclampsia showing higher prevalence than chronic and gestational hypertension. Only maternal age was independently shown to be a risk factor for decreased eGFR at 6 months postpartum (aOR = 1.18/year; 95%CI 1.04–1.34). Conclusion Prior HDP was associated with risk of future CKD, with prior HDPs being more likely to experience evidence of CKD over periods of postpartum follow-up. Routine screening of women following HDP-complicated pregnancies should be part of a postpartum monitoring program to identify women at higher risk. Future research should report on both the eGFR and total urinary albumin excretion to enable detection of women at risk of future deterioration of renal function.

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