Hari M. Behl

Genetic selection and improvement of hard wood tree species for fuelwood production on sodic soil with particular reference to Prosopis juliflora

Abstract This study is a part of a research programme on selection and improvement of fast growing tree species suitable for wood fuel production on sodic wastelands (pH 8.6–10.5). Field trials of nine legumes ( Acacia auriculiformis , A. nilotica , Albizia lebbeck , A. procera , Dalbergia sissoo , Leucaena leucocephala , Pongamia pinnata , Prosopis juliflora , Pithecellobium dulce ) and three other tree species ( Azadirachta indica , Eucalyptus tereticornis and Terminalia arjuna ) were selected for this study. Prosopis juliflora was the most promising species in terms of its biomass productivity ( 68.7 t ha −1 ) and fuel value index (148.8) after 8-yr of growth. Acacia nilotica ranked second. Intra-specific variations were screened at provenance and individual tree level in order to improve fuelwood production potential of P. juliflora through selection and breeding. Successful populations (gene pools) and individuals (genotypes) were cloned and conserved in clonal gardens to produce quality germplasm for plantations on sodic wastelands. Genetic testing, selection and multiplication of selected material are under progress. This will optimise gains in future afforestation programmes on sodic soils.

Fine root biomass and tree species effects on potential N mineralization in afforested sodic soils.

The study was carried out under three types of plantation forest of 40 years, growing on infertile sodic soils, poor in organic matter and N content, of Indogangetic alluvium at Lucknow (26°45′ N; 80°53′ E). Fine root biomass estimated under three forests did not differ much with season, or with species (106–113 g m-2) but varied with soil depth to 0.45 m. The proportion of very fine roots (<0.5 mm) increased with soil depth. Available N in soil was greatest under mixed forest followed by Eucalyptus camaldulensis and Acacia nilotica planted soils. N was maximum in summer season and decreased with soil depth. Nitrogen mineralization during anerobic incubation of 14 days could not be differentiated by tree species, but the monsoon season favoured the process and winter season retarded it. Mineralization decreased with soil depth corresponding to fine roots. There was a reduction in bulk density of soil, pH and EC in forested soil compared to a similar but non forested soil, whereas, organic C and total N increased in forested soils. N mineralization was found to be affected significantly with the fine root biomass and available N content in the soils, whereas negative relations of mineralized N with pH and EC were noticed, though these were not significantly different in this study.

Energy flow, carbon and nitrogen cycling in Populus deltoides clones in north India

Three clones of Populus deltoides were planted on a degraded alluvium from the river Ganges at Lucknow, India (80° 53′E, 26° 42′N). These were studied for biomass production, energy conservation and nitrogen (N) cycling efficiency at 6–7 years of growth stage. The clones did not differ from each other in energy and carbon (C) concentration, however, N concentration decreased significantly in the order G3>D121>G48. The average N concentration of the aerial plant components increased about 21% from lower to upper portions of the trees. Energy values in the root were less than the shoot. The C concentration was greater in woody components in comparison to leaf tissues, whereas the inverse pattern was recorded for N concentration. Energy, C and N contents in the standing crop were greatest in clone G3 followed by G48 and D121 clones. Though the fluxes of energy, C and N were greatest for clone G3 at community levels (tree and grass), at tree populations G48 was found to be more efficient in energy flow as well as C and N cycling. Trees having high N concentration in their foliage (G3) had greater N resorption prior to senescence. Clone G48 was found to be superior to others in N use efficiency based on wood or net production per unit of net N uptake. Integration of N uptake with energy fixation and C intake through a mathematical model estimated about 20 kg ha−1 year−1 of N demand for the sustained production of P. deltoides under the present set of conditions.

Quantification of polyisoprenes from some promising euphorbs

Abstract Quantitative and qualitative variations in hexane and acetone extractables from 10 euphorbs were studied and compared with guayule. There were significant differences in quality, as well as the quantity of oligomers in various euphorbs. Hexane extractables were in relatively lower proportions than the acetone extractables. A regression analysis of the acetone- and hexane-extractable fractions revealed that there was a good correlation. Average molecular weight (M) of polyisoprenes was determined by gel permeation chromatography. In all the taxa investigated, M was far less than that observed in guayule. There appeared to be no correlation between hexane extractables and average molecular weight. GPC chromatograms of the euphorbs showed a unimodal distribution, while most of the cultivars of guayule had a bimodal distribution. The molecular weight distribution (Mwd) range was very narrow in most of the species investigated. High resin content and lack of minimum threshold temperature appear to hinder synthesis of cis-polyisoprenes. Apparently, latex flow seems high but the latex has very low M. Poor biomass and high moisture content further restrict their usefulness.

Species selection for afforestation of sub-standard soil sites with particular reference to biomass production and soil rehabilitation.

Abstract Performance of three, evenaged leguminous tree species (Acacia nilotica, A. auriculiformis and Pithecellobium duke) was evaluated on sodic soil sites (pH 9.6) at Biomass Research Centre, Banthra, Lucknow (north India). Species differed significantly in respect to plant survival, growth and productivity since beginning of its growth as observed at the age of five, 10 and, 15 years. Acacia nilotica had highest average girth at breast height (60.5 cm) and stand biomass (161 Mg ha-1) in spite of its lowest plants survival after 15 years of growth. A. auriculiformis ranked next to it with 131 Mg ha-1 productivity. Basal area ranged from 12.8 to 23 m2 ha-1 in different species. P. duke performed poorly as it had only 71 Mg ha-1 of biomass. Average leaf area per hectare in different species ranged from4,129 m2 ha-1 to 16,090 m2 ha-1 after 15 years of growth. A. nilotica also showed superiority in respect to energy content in woody biomass (2,467 GJ ha-1) and fuel wood value index (1694) as compared to the other two species. At the age of 15 years, litter accumulation over the soil surface resulted in marked reductions in soil pH, electrical conductivity, bulk density and sodium content, and increase in soil porosity, organic carbon and nitrogen content, particularly in the uppermost layer of the mineral soil (0-5 cm). A. nilotica exhibited greater efficiency in terms of soil amelioration followed by A. auriculiformis. The relative ranking of three species was A. nilotica > A. auriculiformis > P. duke, respectively. This indicated greater promise of A. nilotica for biomass production, energy harvest, and soil amelioration on degraded soil sites. Matching tree species to soil conditions needs serious considerations in order to expand site specific afforestation programs and to ameliorate vast tracts of degraded soil sites.

Comprehensive metabolite profiling in distinct chemotypes of Commiphora wightii

Abstract Commiphora wightii (Arn.) Bhandari, known as guggul, produces a medicinally important gum resin which is used extensively by Ayurvedic physicians to treat various ailments. However, most of the studies on C. wightii have been limited to its gum resin. Comprehensive metabolic profiling of leaves, stem and gum resin samples was undertaken to analyse aqueous and non-aqueous metabolites from three distinct chemotypes (NBRI-101, NBRI-102 and NBRI-103) shortlisted from different agro-climatic zones. GC-MS, HPLC and NMR spectroscopy were used for comprehensive metabolomics. Multivariate analysis showed characteristic variation in quinic and citric acids, myo-inositol and glycine (aqueous metabolites) and 2,6-di-tert-butyl-phenol, trans-farnesol and guggulsterones (non-aqueous metabolites) amongst the three chemotypes. Quinic acid, citric acid and myo-ionositol were detected in substantial quantities from leaves and stem samples which provide opportunities for novel nutraceutical and pharmaceutical formulations. Quinic acid, from the leaves, was identified as a marker metabolite for early selection of high guggulsterones-yielding cultivars.