| 1. |
- Mukamuhirwa, Alphonsine, et al.
(författare)
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Concurrent Drought and Temperature Stress in Rice—A Possible Result of the Predicted Climate Change: Effects on Yield Attributes, Eating Characteristics, and Health Promoting Compounds
- 2019
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1660-4601 .- 1661-7827. ; 16:6, s. 1043-1043
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Tidskriftsartikel (refereegranskat)abstract
- Despite the likely increasing co-occurrence of drought and heat stress, not least in equatorial regions, due to climate change, little is known about the combinational effect of these stresses on rice productivity and quality. This study evaluated the impact of simultaneous drought and temperature stress on growth, grain yield, and quality characteristics of seven rice cultivars from Rwanda, grown in climate chambers. Two temperature ranges—23/26 °C night/day and 27/30 °C night/day—together with single or repeated drought treatments, were applied during various plant developmental stages. Plant development and yield were highly influenced by drought, while genotype impacted the quality characteristics. The combination of a high temperature with drought at the seedling and tillering stages resulted in zero panicles for all evaluated cultivars. The cultivar ‘Intsindagirabigega’ was most tolerant to drought, while ‘Zong geng’ was the most sensitive. A “stress memory” was recorded for ‘Mpembuke’ and ‘Ndamirabahinzi’, and these cultivars also had a high content of bioactive compounds, while ’Jyambere’ showed a high total protein content. Thus, climate change may severely impact rice production. The exploitation of genetic diversity to breed novel rice cultivars that combine drought and heat stress tolerance with high nutritional values is a must to maintain food security.
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| 2. |
- Mukamuhirwa, Alphonsine
(författare)
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Drought responses of rice (Oryza sativa) under various drought severity levels and durations in biotron and field
- 2015
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Rapport (populärvet., debatt m.m.)abstract
- Rice is an important staple food in human nutrition. Due to its semi-aquatic phylogenetic origin, rice is mainly produced in water intensive system. However, because of climate change, competition for water with other crops and modernization, rice production is becoming threatened by water shortage. Since drought is predicted to increase in the future, efforts have been made to develop drought adapted rice varieties. However genetic improvement has been slowed by the complex nature of drought and its strong interaction with the environment. Understanding the stress physiology will be a vital asset for the mitigation of climate change impacts in specific environments. This research project proposes to study physiological and grain quality responses of rice to various drought severity levels and durations in field and biotron environments.
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| 3. |
- Mukamuhirwa, Alphonsine, et al.
(författare)
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Effect of intermittent drought on grain yield and quality of rice (Oryza sativa L.) grown in Rwanda
- 2020
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Ingår i: Journal of Agronomy and Crop Science. - : Wiley. - 0931-2250 .- 1439-037X. ; 206, s. 252-262
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Tidskriftsartikel (refereegranskat)abstract
- The climate change will contribute drought and temperature extremes to rice growing systems, especially when cultivated in equatorial regions. To evaluate opportunities to cultivate and breed drought-tolerant rice, seven rice cultivars were evaluated in Rwanda for recurring morphological drought scores, grain yield and components, and quality characteristics. The cultivation conditions, that is site and drought treatment, impacted morphological drought scores, growth and yield attributes, while cultivar affected quality attributes. Thus, site showed a higher impact on grain yield and components than drought and cultivar, with generally a reduced grain yield at the low-temperature site, as a result of low spikelet fertility. Morphological drought scores were generally increased by drought, while drought at the reproductive stage at the high-temperature site was negative for yield and its components. The cultivars "Intsindagirabigega" and "Jyambere" were adapted to high-temperature site conditions. The cultivar "Intsindagirabigega" had the highest amylose content, and "Mpembuke," the highest antioxidant capacity. Thus, climate change with increased temperature and drought extremes may increase rice productivity in cool areas, while especially drought at reproductive stage will be detrimental in low altitude areas with high temperature. Cultivar variation indicated opportunities for selection and breeding of climate change tolerant rice cultivars which should be of immediate priority.
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| 4. |
- Mukamuhirwa, Alphonsine
(författare)
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Grain Yield and Quality Traits of Rice (Oryza sativa L.) Cultivars under Intermittent Drought and Contrasting Temperatures : physiological, biochemical and molecular characterisation
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rice (Oryza sativa) has evolved in a semi-aquatic tropical environment and therefore thrives better in a water intensive system and optimal temperature between 25 and 30°C. With the future climate change, frequent droughts and heat stress are predicted to happen simultaneously in field but little is known about their combined effects on rice productivity and quality. This thesis investigated the effects of high temperature combined with recurring drought at different stages of plant development and identified quantitative trait loci associated with drought tolerance. Drought sensitivity, growth characteristics, grain yield and its component traits, and grain quality traits were also evaluated in seven rice cultivars grown in Rwanda. The results showed that grain yield was strongly influenced by the number of panicles per plant and spikelet fertility. A combination of high temperature and repeated drought at seedling and tillering stages dramatically limited panicle development, whereas spikelet fertility was negatively affected by drought at the reproductive stage. Grain yield was reduced by 30% to 100% as a result of drought and temperature stress as compared with well-watered control conditions. Quantitative trait loci (QTL) for number of panicles per plant were found on chromosomes 1, 4, and 8 whereas QTL for spikelet fertility were located on chromosomes 1, 5 and 9. Four QTL each were found for grain yield after drought at seedling stage (located on chromosomes 1, 4, 7, 9) and for grain yield after drought at tillering stage (located on chromosomes 6, 8, 11, and 12). These QTL could be introgressed into elite cultivars for improvement of their adaptation to intermittent drought. The cultivars displayed genetic diversity in their tolerance to stresses and quality characteristics. ‘Intsindagirabigega’ and ‘Jyambere’ were adapted to high temperature site conditions. ‘Intsindagirabigega’ had the highest amylose content. ’Ndamirabahinzi’ and ‘Mpembuke’ were rich in total phenolic and total antioxidant capacity, and displayed a beneficial stress memory. ‘Jyambere’ had high total protein content and high content in mineral elements together with ‘Nemeyubutaka’ and ‘Ingwizabukungu’. The results in this thesis indicate potential for developing resilient, high-yielding and nutritionally rich rice cultivars that can be grown in stressful environments.
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| 5. |
- Mukamuhirwa, Alphonsine, et al.
(författare)
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Quality and Grain Yield Attributes of Rwandan Rice (Oryza sativa L.) Cultivars Grown in a Biotron Applying Two NPK Levels
- 2018
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Ingår i: Journal of Food Quality. - : Hindawi Limited. - 0146-9428 .- 1745-4557. ; 2018
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Tidskriftsartikel (refereegranskat)abstract
- High-yielding rice cultivars with good processing quality and rich in nutrition suitable to a changing climate are of particular importance for future rice-based food production. Here, seven Rwandan rice cultivars were grown in a climate chamber of the biotron facility at the Swedish University of Agricultural Sciences, to be evaluated for their grain yield, nutritional composition, and dough mixing properties. Two different levels of inorganic fertilizer were applied weekly from the seedling stage until flowering. Significant differences for grain yield and quality attributes were found between cultivars. Jyambere showed significantly the highest yield while Ingwizabukungu, Nemeyubutaka, and Jyambere were high in mineral elements content. Ndamirabahinzi and Mpembuke had the highest levels of TPC and TAC. Generally, the lower fertilizer dose resulted in a better performance of the cultivars for both yield and quality attributes. Significantly higher content of Fe, Ca, and Ba was found in grains from the moderate fertilizer dose, whereas K, Na, P, S, Zn, Cd, and Pb increased in grains from the higher fertilizer dose. The cultivar Ndamirabahinzi showed less variability of evaluated characters across fertilizer doses. The results from this study may be used for rice breeding of cultivars with high yield and good grain quality.
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| 6. |
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