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Title: Role of K-solubilizing rhizobacteria in potassium nutrition of maize (Zea mays L.)
Authors: Imran, Muhammad
Keywords: Agriculture and Veterinary Sciences
Soil Sciences
Issue Date: 2020
Publisher: University of Sargodha, Sargodha.
Abstract: Potassium (K) is one of the major mineral elements required to sustain plant growth, and also involved in several key plant physiological and metabolic processes. With considerable application of nitrogen (N) and phosphorus (P) fertilizers, sustainable K management for crop plants lacks overall prudence in relation to its widespread deficiency in Pakistan. Farmers are usually unaware of the K deficiency due to their lack of information on soil K reserves and irrational fertilizer recommendations. The crop yield losses associated with K deficiency have gained its due attention among farming as well as scientific community in recent time. With increasing fertilizer cost, environmental degradation and declined food quality, it is therefore important to have an eco-friendly K management plan for better crop productivity. Maize is an exhaustive crop that removes large quantities of plant nutrients and requires relatively higher soil fertility for higher biomass production. Perpetual K deficiency in soil is one of the major constraints to achieve the higher production potential of maize in Pakistan. Use of plant beneficial microbes have recently been emerged as an effective biofertilizer option to improve plant growth and soil quality. Certain microbes solubilize and/or mobilize various fractions of K by releasing acidic metabolites thus improve plant nutrition. In this project, we conducted the isolation of potassium solubilizing bacteria (KSB) from the rhizosphere soil, collected from different maize growing areas of Punjab, Pakistan. The KSB were purified and screened both on qualitative as well as quantitative basis in the K supplemented media. Four of the isolates, belonging to Kelsiella, Ensifer and Arthrobactor species, were found more efficient in solubilizing K and exhibited higher potential of plant growth promotion. Furthermore, growth conditions (i.e. temperature, pH and carbon source) were optimized for K solubilization of KSB and showed that glucose was best carbon source when provided at 25 ºC and 7 pH. Most efficient KSB strain, identified as Klebsiella oxytoca strain 1374, was tested against five different sources of K [soil K, waste mica, K2SO4, waste mica enriched compost (WM-EC) and K2SO4 enriched compost (K2SO4-EC)] on maize as a test crop under pot and field conditions. The results from the pot and field trials during first year of crop experiments, showed that maize growth, yield, grain quality and soil health indicators were substantially improved by both mineral and compost enriched K2SO4 under KSB inoculated conditions. During both pot as well as field trials of first year, use of WM-EC along with KSB inoculation not only improved soil health parameters successfully, but also improved maize growth, yield and grain quality compared to both control and WM treatment. In second year trial under field conditions, we employed different combinations of K sources [i.e. 100% K2SO4, 25% WM-EC + 75% K2SO4, 50% WM-EC + 50% K2SO4, 75% WM-EC + 25% K2SO4 and 100% WM-EC] and found that combination of 25% WM-EC + 75% K2SO4 integrated with selected KSB inoculant improved maize K nutrition and soil potassium fertility. It can be concluded that K amendment i.e. K enriched compost combined with the most efficient KSB inoculant can improve the production potential of maize by improving plant K nutrition as well as soil K fertility.
Gov't Doc #: 22188
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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