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Biological transplant amendments intensify growth, physiological profiling and rhizosphere stochiometry of air-layered litchi (Litchi chinensis Sonn.) saplings
* 1 , 2 , 2 , 3 , 4
1  Department of Fruit Science, Dr YS Parmar University of Horticulture and Forestry, Nauni 173 230, Solan, HP, India
2  RHRTS, Dr YS Parmar University of Horticulture and Forestry, Dhaulakuan 173 031, Sirmour, HP, India
3  Department of Plant Pathology, Dr YS Parmar University of Horticulture and Forestry, Nauni 173230, Solan, HP, India
4  Department of Basic Sciences (Microbiology), Dr YS Parmar University of Horticulture and Forestry, Nauni 173230, Solan, HP, India
Academic Editor: Wilfried Rozhon


The present investigation was carried out to study the effectiveness of PGPR probiotics on air-layers root development on litchi (Litchi chinensis Sonn.) mother plants. The interactive effects of PGPR transplant amendments on plant survival, physiological profiling and rhizosphere stochiometry of transplanted air-layered saplings were also studied. Six PGPR transplant amendments i.e., Pseudomonas florescence, Azotobacter chroococcum, K-mobilizers and AM fungi were inoculated in different combinations. The air-layering technique was carried out by removing the bark of the shoots along with cambium (2 cm deep) during August and September.The uniform air-layers were transplanted in the month of October at 30 x 60 cm using double-row planting method replicated thrice. Twenty-five years healthy progeny of mother plants were maintained for air layering operation. The detached rooted air layers from these mother plants were further transplanted in rooting media. The treatments comprised of the combinations namely, T1, litchi orchard soil+ sand (1:1); T2, sand+AM fungi+ Azotobacter chroococcum (1:2:1); T3, sand+Pseudomonas florecence + K-mobilizer (1:1:1); T4, AM fungi+ K-mobilizers (1:1); T5, P. florecence+ A. chroococcum+ K-mobilizer (1:1:1); T6, sand+P. florecence (1:2); T7, uninoculated control supplemented with FYM along with N:P:K 60:30:30) for field performance. The inoculation of Metarrhizium in bulk as well as rhizosphere soil following dual application of PGPR probiotics was followed in T4-T6 combinations. Treatment application of sand+AM fungi+ A. chroococcum (1:2:1) significantly improved survival rate, plant height, stem diameter, leaf number, leaf area and total leaf chlorophylls of the saplings as compared to uninoculated control. Root soil ratio of resident microbes at 15 cm depth was also worked out in the rhizosphere zone and non-rhizosphere zone. Microbial biomass of A. chroococcum Pseudomonas, K-mobilizers and AM fungi was increased by 2.59, 3.39, 2.42 and 2.77 times, respectively. Acid phosphatase, alkaline phosphatase and dehydrogenase enzyme activity was increased in rhizosphere that can be a good indicator of phosphorus nutrition for survival of the saplings. The rhizo-inoculation significantly affected leaf nutrient concentration as ΣDOP indexes which showed an increase in N, P, K Ca, Mg and micronutrient concentration in the leaves of saplings. Principal component analysis induced the differences at various PGPR probiotics applied has identified maximum of the total variance based on the Eigen value (>1) which explained PC1 (86.82%), PC2 (93.11%), PC3 (96.41%) and (98.22%) of the cumulative variance. The study indicated PGPR transplant amendments coupled with Metarrhizium in saplings can be a promising technology to improve survival rate during hardening for the production of elite litchi planting material.

Keywords: Air-layering; microbial inoculants; organic nutrients; Solubilizers