New varieties required to offset climate change effects
A COMBINATION of rising temperatures, low and high rainfall patterns associated with climate change, land degradation and socio-economic stressors are likely to heighten the vulnerability of crop production systems in Zimbabwe.
Climate change has had a negative effect on crop production not only in Zimbabwe but worldwide. The El Nino-induced drought experienced last season is an indication of the rapidly changing weather conditions that hamper food production.
Climatic events over the past decades resulting in increased temperatures mean that there is an urgent need to develop more climate resilient maize varieties.
Increased atmospheric events have resulted in rainfall anomalies characterised by droughts, heavy rains and storms. These events have negatively affected the country’s agricultural sector.
There also has been an increase in pests and diseases, soil erosion and with a mismanaged ecosystem, this has resulted in reduced productivity of the soils. Crop production has declined over the years with the nation producing 511 000 tonnes of maize last year.
Addressing stakeholders in the agricultural sector at the Zimbabwe Plant Breeders Association (ZPBA) first anniversary in Harare last week, climate and weather expert, Leonard Unganai, said there was need for plant breeders to develop varieties with both drought and heat stress tolerance characteristics.
“Crop model simulations using future climate scenarios for temperature and precipitation showed that a two degrees Celsius increase in temperature will result in a greater reduction in maize yield than a 20 percent decline in precipitation in eastern and southern Africa.
“The frequency of extreme heat events, drought and heavy rainfall are expected to increase with climate change,” Unganai said.
By 2050, temperatures are expected to increase throughout maize mega- environments within sub-Saharan Africa by an average of 2,1 degrees celsius.
Despite the increase in temperatures, agriculture is expected to provide for an additional 3,5 billion people and food production will need to increase by 70 percent to feed the growing populations. However, climate change scenarios show that agricultural production will be negatively affected and is expected to affect food security in many regions.
“Focus of crop breeders in Zimbabwe has always been biased towards drought tolerance, but observed and future climate change suggests the need for a high temperature tolerance as well. Tolerance to both drought and waterlogging is also increasingly becoming important in some locations,” Unganai added.
There is always a correlation between maize production and rainfall in Zimbabwe, less rain negatively affects output and more rain results in increased yield. However, production in Zimbabwe is happening in an environment that is complicated with climate change adding to the stressors that already exists.
The socio-economic environment, land degradation, bio-physical conditions soil fertility and the water holding capacity of the soils can be very challenging.
In areas such as Buhera the land degradation itself without the effects of climate change affects yields.
Unganai urged plant breeders to come up with new maize varieties with drought and heat tolerance to reduce the effects of climate change on farming systems in Zimbabwe.
“However, maize breeding alone may be insufficient to increase yield while adapting to climate change. There is also need to pay attention to farming practices. Future vulnerability hotspots should be the focus of climate adapted maize breeding to increase adaptive capacity.
“Effective management of land, water and soil resources should always be considered while planning adaptation measures. Farmers do not grow crops, but create the right conditions for crops to grow,” he said.
Smallholder farmers’ access to improved germplasm will be important in building their resilience to climate change.
Jill Cairns of International Maize and Wheat Improvement Centre (CIMMYT) Zimbabwe concurred with Unganai stressing the need for plant breeders to come up with newer varieties considering the fact that in Zimbabwe there are old varieties that are on the market that are no longer suitable for the current climatic conditions.
“Varieties over 10 years were not bred for the current environment. For plant breeders the changing climatic conditions, is an opportunity for them to come up with new varieties that are drought and heat tolerant and can increase yields,” Cairns said.
The Zimbabwe Plant Breeders Association’s main objective is to create a future in which public and private sectors work independently and together to deliver varieties and improved germplasm to the public.