Scarcity of sufficient amount of canal water for irrigation compelled the farmers to irrigate their crops with tube well water. The quality of ground water is deteriorating day by day due to rapid industrialization and urbanization. According to estimation about 70-75% of ground water that is being pumped out in Pakistan is brackish in nature. The continuous use of this water for irrigation leads to develop soil salinity which severely affects the physiological processes of plants. These adverse effects of salinity may be attributed to non-availability of water, disturbance in nutrient uptake causing deficiency and ion-toxicity to plants. Salinity and sodicity stresses are ever-present threats to crop yields, especially where tube well irrigation is an essential aid to agriculture.
It has been noticed that when the plant is under salinity stress then its ethylene (a growth hormone) production is increased. No doubt it is required for the optimal production of plant but up to certain limit. After that it has inhibitory effect on the plant growth and development. Ethylene is produced in plants from 1-aminocyclo propane-1-carboxylate(ACC), the immediate precursor of ethylene.
As plant has not any mechanism to stop this excessive ethylene production during salt stress and ultimately yield is reduced. But nature has gifted us certain soil microbes that have an enzyme ACC-deaminase which utilize the ACC (an immediate precursor of ethylene) as an energy source and cleavage it to NH3 and α-ketoglutaric acid. Treating of such microbes with crops jut prior to planting significantly reduced the salt stress in plants.
In an experiment on maize crop irrigated with brackish water [EC, 5dSm-1; SAR, 10 (mmol L-1)1/2] we have seen that plants treated with microbes having ACC-deaminase activity, increased the crop yield up to 30 % over untreated plant. Thus this is one of the promising techniques to use brackish water for sustainable crop production in agriculture.
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