DEVELOPMENT OF ENDOPHYTIC MICROBIAL CONSORTIUM TO MITIGATE MOISTURE STRESS CONDITIONS IN MAIZE CROP (Zea mays L.)
Loading...
Date
2023-11-08
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Acharya N G Ranga Agricultural University
Abstract
Maize is the third most vital crop after the rice and wheat in India but it stands first in the context of potential for highest productivity. Maize has been used for multi purposes, for instance as a food for human, feed for livestock and also used as a raw material in many industries. Drought stress has been reported to cause yield reductions of up to 40% in maize around the world and it was also considered as nutrient exhaustive crop. The quality and yield of crop may change due to the association of endophytic microbes that reside in plants asymptomatically and they were known protect plant from abiotic and biotic stress.
The present investigation was aimed to develop an endophytic microbial consortium which is an alternative approach to minimize the use of chemical fertilizers and to mitigate stress conditions in maize without affecting ecosystem. A total of 106 endophytic bacterial morphotypes were isolated from surface sterilized maize plant tissues including roots, stem, leaf and kernels collected from various regions of AP which includes Srikakulam, Vijayanagaram, Visakhapatnam, East Godavari, Guntur, Kurnool and Ananthapuram.
Among all 36 efficient water stress mitigating and plant growth promoting isolates were selected and screened to 16 effective isolates based on quantitative analysis of plant growth promoting attributes. Significant isolates were identified as genera Gordonia,Microbacterium, Kosakonia, Priestia, Bacillus, Cellulosimicrobium, Pantoea, Pseudomonas, Klebsiella and Methylorubrum by 16S rRNA gene sequencing.
Efficient 7 isolates were selected namely Kosakonia radicincitans (NL3E3), Priestia megaterium (PdS3E1), Priestia aryabhattai (PL3E2) Bacillus licheniformis (VaR3E1), Pseudomonas aeruginosa (LS3E1), Klebsiella pneumonia (LS3E3) and Methylorubrum populi (LL3E1) for compatiability and endophytic colonization studies. Based on the obtained results formulated microbial consortium (MC-4)
xxii
Bacillus megaterium+ Bacillus licheniformis+ Klebsiella pneumoniae+ Methylorubrum populi was seclected for pot and field experiments.
In pot culture experiment microbial consortium inoculated treatments imposed with (75% WHC) water stress T9 (100% RDF) and T8 (75% RDF) were found to excel in many plant and soil chemical properties when compared to un-inoculated control. For instance chlorophyll stability index T9 (138.67%) T8 (133.33%), relative water content T9 (95.20%), organic carbon ccontent was found highest in T5 (0.39%) and T8 (0.38%), available nitrogen in soil was more in T9 (145.61 Kg ha-1) and T8 (141.65 Kg ha-1), available phosphorous was higher in T8 (67.68 Kg ha-1), available potassium is more in T9 (345.86 Kg ha-1). The N, P and K uptake was found significantly higher in T9 with 13.98 g plant-1, 3.38 g plant-1 and 17.29 g plant-1 respectively.
Total microbial population in rhizosphere and endosphere was found higher at flowering stage. Total bacterial, fungal and actinomyces were reported highest in T9 with (9.99 Log CFU g-1 of soil), T8 (5.66 Log CFU g-1 of soil) and T9 (4.24 Log CFU g-1 of soil) respectively. At vegetative stage maximum colonization of endophytic bacteria was found in roots followed by stem and least colonization was found in leaves. Contradictory to that at flowering stage maximum endophytic bacterial population was observed in stem followed by roots and leaves. Higher plant biomass was produced by T9 (259.67 g) and grain yield was found highest in T9 (53.56 g) followed by T8 (51.39 g)
In field conditions maximum CSI was observed for T9 (138.67%) and highest RWC was recorded in T7 (95.13%). The production of H2O2 was higher in treatments given with lower number of irrigations and so the peroxidase activity. The organic carbon in soil was highest in T7 (0.45%). The available nitrogen in soil was more in T9 (225.29 kg ha-1) and T8 (209.09 kg ha-1), available phosphorous was higher in T9 (70.34 kg ha-1) and T8 (69.92 kg ha-1), available potassium is more in T9 (390.62 kg ha-1), T8 (360.59 kg ha-1). The N, P and K uptake was found significantly higher in T8 (690.03 Kg ha-1), T9 (182.45 Kg ha-1) and T9 (425.61 Kg ha-1) respectively. Total microbial population was found highest at flowering stage and the endophytic microbial population was found highest in root endosphere followed by stem, leaf and kernels.
Significantly higher dehydrogenase activity was found in T9 (58.90 μg of TPF g-1 of soil day-1) at flowering stage and maximum phosphatasee activity was found in T8 (94.97 μg pNP g-1 of soil h-1). At flowering stage T9 (24054 Kg ha-1) and T8 (22332 Kg ha-1) were found to produce significantly higher amount of plant biomass. Significantly more yields were obtained in T6 (7963 Kg ha-1) followed by T9 (7644 Kg ha-1). Considerably higher net returns were obtained for T6: 5 Irrigations + 100 % RDF + MC (Rs. 113717/- ha-1) followed by T9:7 Irrigations + 100 % RDF + MC (Rs. 106325/- ha-1) and T8:7 Irrigations + 75 % RDF + MC (Rs. 102539/- ha-1).
Thus the current study suggested that significant net returns can be obtained even under water deficit conditions when inoculated with endophytic microbial consortium (Bacillus megaterium+ Bacillus licheniformis+ Klebsiella pneumoniae+ Methylorubrum populi) by improved plant growth and yields due to enhanced osmotolerance and mineralization of nutrients. Nearly 120 mm of water (2 irrigations) and 25% of RDF can be minimized for crop production without affecting yield and net returns.