Tree diversity and community composition in sacred forests are superior than the other community forests in a human-dominated landscape of Meghalaya

Integration of organics in nutrient management for rice-wheat system improves nitrogen use efficiency via favorable soil biological and electrochemical responses

INTRODUCTION

The contrasting soil management in flooded-transplanted rice (Oryza sativa) and dry-tilled wheat (Triticum aestivum) poses a challenge for improving low nitrogen use efficiency (NUE) of the rice-wheat system. Integration of organics in nutrient management can bring in changes favoring efficient N uptake via changes in growing conditions and soil responses.

MATERIALS AND METHODS

This study reported the results of a 15-year-long experiment on integrated nutrient management (INM) systems for rice-wheat cropping. The INM included substituting ~50% of chemical fertilizers via (i) including a legume crop (Vigna radiata) in the sequence and its biomass incorporation (LE), (ii) green manuring with Sesbania aculeata (GM), (iii) farmyard manure application (FYM), (iv) 1/3 wheat stubble in situ retention (WS), and (v) 1/3 rice stubble in situ retention.

RESULTS AND DISCUSSION

The INM strategies resulted in improved NUE compared to 100% chemical fertilizers (F). The INM had significantly higher net N mineralization and improved biological activity aligning with the NUE trends. The reductions in redox potential (Eh) and pH during rice season improved NUE under integrated management. Highly reduced conditions favored N mineralization and plant availability in form of NH 4 + - N resulting in enhanced uptake efficiency, in rice crop. The soil organic carbon (C) significantly increased in INM, and an effect of the active C fractions was evident on the NUE of the wheat crop.

CONCLUSION

The results showed that these INM strategies can immensely benefit the rice-wheat system via improvement in biological health along with electrochemical changes for flooded rice, and labile-C-assisted improvement in soil conditions for wheat.

Morpho-physiological and demographic responses of three threatened Ilex species to changing climate aligned with species distribution models in future climate scenarios

The success of a species in future climate change scenarios depends on its morphological, physiological, and demographic adaptive responses to changing climate. The existence of threatened species against climate adversaries is constrained due to their small population size, narrow genetic base, and narrow niche breadth. We examined if ecological niche model (ENM)-based distribution predictions of species align with their morpho-physiological and demographic responses to future climate change scenarios. We studied three threatened Ilex species, viz., Ilex khasiana Purkay., I. venulosa Hook. f., and I. embelioides Hook. F, with restricted distribution in Indo-Burma biodiversity hotspot. Demographic analysis of the natural populations of each species in Meghalaya, India revealed an upright pyramid suggesting a stable population under the present climate scenario. I. khasiana was confined to higher elevations only while I. venulosa and I. embelioides had wider altitudinal distribution ranges. The bio-climatic niche of I. khasiana was narrow, while the other two species had relatively broader niches. The ENM-predicted potential distribution areas under the current (2022) and future (2050) climatic scenarios (General Circulation Models (GCMs): IPSL-CM5A-LR and NIMR-HADGEM2-AO) revealed that the distribution of highly suitable areas for the most climate-sensitive I. khasiana got drastically reduced. In I. venulosa and I. embelioides, there was an increase in highly suitable areas under the future scenarios. The eco-physiological studies showed marked variation among the species, sites, and treatments (p < 0.05), indicating the differential responses of the three species to varied climate scenarios, but followed a similar trend in species performance aligning with the model predictions.

Chloroplast Genome of Lithocarpus dealbatus (Hook.f. & Thomson ex Miq.) Rehder Establishes Monophyletic Origin of the Species and Reveals Mutational Hotspots with Taxon Delimitation Potential

There is phylogenetic ambiguity in the genus Lithocarpus and subfamily Quercoideae (Family: Fagaceae). Lithocarpus dealbatus, an ecologically important tree, is the dominant species among the Quercoideae in India. Although several studies have been conducted on the species' regeneration and ecological and economic significance, limited information is available on its phylo-genomics. To resolve the phylogeny in Quercoideae, we sequenced and assembled the 161,476 bp chloroplast genome of L. dealbatus, which has a large single-copy section of 90,732 bp and a small single-copy region of 18,987 bp, separated by a pair of inverted repeat regions of 25,879 bp. The chloroplast genome contained 133 genes, of which 86 were protein-coding genes, 39 were transfer RNAs, and eight were ribosomal RNAs. Analysis of repeat elements and RNA editing sites revealed interspecific similarities within the Lithocarpus genus. DNA diversity analysis identified five highly diverged coding and noncoding hotspot regions in the four genera, which can be used as polymorphic markers for species/taxon delimitation across the four genera of Quercoideae viz., Lithocarpus, Quercus, Castanea, and Castanopsis. The chloroplast-based phylogenetic analysis among the Quercoideae established a monophyletic origin of Lithocarpus, and a closer evolutionary lineage with a few Quercus species. Besides providing insights into the chloroplast genome architecture of L. dealbatus, the study identified five mutational hotspots having high taxon-delimitation potential across four genera of Quercoideae.