Impact of genetic improvements of rice on its water use and effects of climate variability in Egypt

Authors: MEHANA, MOHAMED - Agricultural Research Center Of Egypt; ABDELRAHMAN, MOHAMED - Agricultural Research Center Of Egypt; EMADELDIN, YASMIN - Agricultural Research Center Of Egypt; Rohila, Jai; KARTHIKEYAN, RAGHUPATHY - Clemson University

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2021
Publication Date: 9/10/2021
Citation: Mehana, M., Abdelrahman, M., Emadeldin, Y., Rohila, J.S., Karthikeyan, R. 2021. Impact of genetic improvements of rice on its water use and effects of climate variability in Egypt. Agriculture. https://doi.org/10.3390/agriculture11090865.
DOI: https://doi.org/10.3390/agriculture11090865

Interpretive Summary: Natural resources such as land and water are limited for rice production. With increasing population there is an urgent need to grow more rice from marginal agricultural lands and by using less water. Genetic improvements of rice germplasm and the release of improved varieties are viable solutions to meet this challenge. Egypt is a unique country which has only one major source for its freshwater supplies, the Nile river. To remain competitive, rice breeders have aggressively improved Egyptian rice varieties for reduced water requirements. We analyzed impacts of climate variables, improved cultivars, and various cultivar substitution scenarios as a case study. The results indicated that Egypt’s rice cultivated area is declining at a rate of -1.7% per year and the production at -1.9% per year. An in-depth analysis of data revealed that while one cultivar (Sakha101; days to maturity = 140) could have higher production (9.79 metric ton/ha), another cultivar (Sakha102; days to maturity = 125) shows higher water productivity (1.19 thousand m3 water used/metric ton of rice). We conducted a classical cultivar substitution analysis and found that the improved cultivars (e.g. Giza179, Sakha 107) that were of short duration (days to maturity = 122) and high yielding (9.26 metric ton/ha) were capable of providing higher net savings on water (795.55 thousand m3) compared to the average of other cultivars. These water savings can be utilized to increase rice acreage and for producing more rice in the country. In addition, Egypt has another unique weather pattern with more precipitation during off-season than during the growing season. We analyzed long-term and short-term effects of certain climate variables on rice production and found that on- and off- season precipitation had mainly long-term impacts, but relative humidity during the rice growing season had greater short-term impacts possibly due to affecting physiology of the plant via vapor pressure deficit. Overall, the results emphasized a need for robust rice breeding programs for abiotic stress tolerance to safeguard the world’s food security in a sustainable manner.

Technical Abstract: Developing and disseminating improved rice cultivars with higher productivity is a key solution for efficient use of limited natural resources such as land and water. We investigated trends in rice cultivated areas and overall production in Egypt between 2000 and 2018. Results indicated that there were significant annual reductions in both the rice cultivated area (- 1.7% per year) and production (- 1.9% per year). We identified rice cultivars that showed potential to grow under limited water resources with higher grain and water productivity. Cultivar Sakha101 showed the highest land unit productivity but Sakha102 showed highest water unit productivity. The impact of deployment of newly released rice cultivars were analyzed by substitution scenarios and it was found that cultivars Giza179 and Sakha107 substitutions have a potential to increase rice yields by 15.79% and 22.6%, respectively, over the average of popular older varieties and could bring an increase in water savings up to 0.8 million m3 compared with 2018 as the base year. Long-term impacts of climate variability for minimum and maximum temperature, relative humidity, average precipitation on- and off-season on rice productivity were also analyzed using the autoregressive distributed lag (ARDL) model. The results revealed that climate variability has an overall negative impact on rice productivity. Specifically, minimum temperature during the growing season and on and off- season precipitation had major long-term impacts and relative humidity had a pronounced short-term impact. These analyses are critical to guide strategic management plans to mitigate short and long-term climate effects on overall rice production and for developing and deploying improved rice varieties in Egypt and elsewhere for sustainable rice production.