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Elton Manguwo
AS the next tobacco growing season fast approaches, Kutsaga Research has warned growers of the danger posed by salt injury to float seedling production systems under the prevailing hot and windy weather conditions.
In a statement yesterday, Kutsaga head training, extension and public engagement Dr Dzingai Rukuni said during hot and windy weather conditions the tobacco float seedling production system could expose seedlings to salt injury.
“The prevailing environmental conditions tend to promote excessive evaporation from the surface of the growing media used in float seedling production systems. This rapid evaporation can result in the deposition and concentration of fertiliser salts on the surface,” said Dr Rukuni.
The accumulation of fertiliser salts on the surface can create a highly saline environment that can prove detrimental to the delicate tobacco seedlings growing in the float trays especially soon after germination and early growth.
“Growers must be vigilant in monitoring their float systems and take appropriate measures to mitigate the risk of salt injury to the developing tobacco plants,” said Dr Rukuni highlighting that taking proactive measures to address the issue would help ensure a robust and productive crop for the upcoming season.
The initial symptoms of salt injury in tobacco float seedlings manifest as a browning of the plant’s growing point or heart while the leaf tips that are in direct contact with the growing media may exhibit signs of burning or scorching.
“As the salt injury progresses, the necrosis or death of plant tissue extends from the leaf tips and margins inward to the growing point of the seedling, which becomes severely compromised or killed altogether,” said Dr Rukuni.
More so, the roots can also be severely impacted by the high concentration of soluble salts. This induced stress on the root system can predispose the seedlings to a range of harmful root diseases, such as Pythium root rot and Rhizoctonia stem rot.
“Growers must be diligent in monitoring all components of their float seedling production system to ensure soluble salt levels do not reach a point where they adversely affect the health and development of the tobacco plants,” said Dr Rukuni.
One of the key indicators used to assess the potential for salt-related issues in tobacco float seedling production is the electrical conductivity (EC) of the growing media.
“EC provides a direct measurement of the concentration of soluble salts present, serving as a valuable tool for growers to gauge the risk of salt injury to their seedlings,” said Dr Rukuni.
Kutsaga has since identified several effective strategies that growers can implement to minimise the risk of salt injury in their tobacco float systems. One of the most promising solutions is the use of vlei grass mulch, which has been found to be the best material for reducing salt injury-related mortalities in the float beds.
Online Reporter