POTASSIUM- THE QUALITY ELEMENT IN ENHANCING PRODUCTIVITY AND ALLEVIATING DETRIMENTAL EFFECT OF ABIOTIC STRESS IN PLANTS

A Thesis Submitted to the Faculty of Agriculture Sher-e-Bangla Agricultural University, Dhaka in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY IN SOIL SCIENCE SEMESTER: JANUARY - JUNE, 2019

ABSTRACT Potassium fertilizer management is beneficial for improving growth, yield and yield components of field crops under moisture stress condition. Three field experiments were conducted at the research farm of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during the rabi season of 2016-2018 to evaluate the effects of potassium fertilizer enhancing the productivity and alleviating detrimental effect of abiotic stress along with other recommended fertilizer on the growth, yield, nutrient management, shelf life of the plant product and soil chemical properties, the research was conducted based on selected wheat (BARI gom26), rice (BARI dhan28) and carrot (New Kuroda) variety. The experiments were laid out in Split Plot Design and RCBD method with three replications. The first experiment was conducted on wheat in rabi season with sixteen treatment combination (4 levels of irrigation X 4 levels of K doses) viz. I 0 = control (normal irrigations), I = Water stress at vegetative stage, I 2 = Water stress at flower initiation stage, I 3 = Water stress at milking stages and K = 0 kg K/ha, K 1 = 60 kg K//ha, K 2 = 90 kg K/ha, K = 120 kg K/ha. Growth and yield contributing characters mainly plant height, number of spikelet’s, thousand grains weight of wheat crop were significantly influenced by the potassium fertilizer and water stress at different growth stages. The highest grain yield of wheat (4.04 t/ha) was observed under 120 kg K/ha from I 0 K 3 3 treatment combination, while the lowest grain yield (2.29 t/ha) was recorded from I 0 K 1 and I 0 K treatment combinations respectively. Among the combined effect of water stress conditions and different doses of potassium I 2 0 K combination provided the best result. The second experiment was conducted on rice in rabi season with eleven treatments including control viz. T 3 = Control (no fertilizer), T 2 = Fertilizer recommended dose for BRRI dhan28. (FRD) N 120 P 18 K 75 S 13 Zn 1.5 , T 3 1 = 25% K supplement by cowdung (1.25 t/ha) + 75% K (56.25 kg /ha K) from MoP, T = 25% K supplement by poultry liter (2.20 t/ha) + 75% K (56.25 kg/ha K) from MoP, T 5 4 = 25% K supplement by vermicompost (1.87 t/ha) + 75% K (56.25 kg/ha K) from MoP, T 6 = 50% K supplement by cowdung (2.50 t/ha) + 50% K (37.5 kg/ha K) from MoP, T = 50% K supplement by poultry liter (4.40 t/ha) + 50% K (37.5 kg/ha K) from MoP, T = 50% K supplement by vermicompost (3.75 t/ha) + 50% K (37.5 kg/ha K) from MoP, T 9 8 = 75% K supplement by cowdung (3.75 t/ha) 1 0 7+ 25% K (18.75 kg/ha K) from MoP, T = 75% K supplement by poultry liter (6.60 t/ha) + 25% K (18.75 kg/ha K) from MoP, T 11 10 = 75% K supplement by vermicompost (5.62 t/ha) + 25% K (18.75 kg/ha K) from MoP. The study in aspect of growth and yield contributing characters mainly plant height, effective tillers/hill, panicle length, filled grain/panicle, thousand grain weight, and harvest index and grain yield of boro rice. The maximum grain yield of rice (6.55 t ha -1 ) was produced from T treatment which was significantly different from the T 1 treatment (2.35 t ha -1 8 ). The third experiment was conducted on carrot with eight treatments including control viz. T 1 = 0 kg K/ha, T 2 = 20 kg K/ha, T 3 = 40 kg K/ha, T 4 = 60 kg K/ha, T = 100 kg K/ha, T 7 = 120 kg K/ha, T = 140 kg K/ha. Storage quality of carrot indicated that after seven days the lowest moisture reduction percentage was observed in K 8 (20.39%) while the highest moisture reduction percentage was found in K 0 (61.45%) followed by K 1 5 (60.24%). After 14 and 21 days same trend of moisture reduction were found. In room temperature, K treatment provided the best result and enhanced the shelf life of carrot. So, it can be suggested that the improvement of K- nutritional status of plants might be of great importance for the survival of crop plants under environmental stress conditions and potassium fertilizer with other recommended fertilizers would be ideal for better crop growth, increasing yield and shelf life of crops. 5 5 = 80 kg K/ha, T 6