S. L. Swamy

Effect of auxins (IBA and NAA) and season on rooting of juvenile and mature hardwood cuttings of Robinia pseudoacacia and Grewia optiva

Juvenile (2 year old trees) and mature hardwood (15 year old trees) cuttings of Robinia pseudoacacia and Grewia optiva were tested for their capacity to form roots. Cuttings were prepared in spring, monsoon and winter seasons and treated with different concentrations (250, 500 and 750 mg/l) of IBA and NAA. These were planted in a mist chamber maintained at 25 ± 1 °C with relative humidity > 70%. Juvenile cuttings of both species rooted significantly better than mature hardwood cuttings in all three seasons, and the age effect was more pronounced in auxin treated cuttings. The highest rooting in juvenile (83.3%) and mature (66.6%) cuttings was observed with the NAA (500 mg/l) treatment in R. pseudoacacia during the spring season. In G. optiva, IBA (250 mg/l) in the monsoon season was most effective and yielding a maximum of 80% and 70% rooting in juvenile and mature cuttings, respectively. Auxin treatments also significantly enhanced the number of roots, root length, leaf number and leaf area. Statistical analysis of data revealed that interactions between age, season and treatments were significant at P < 0.05 level for R. pseudoacacia and non-significant for G. optiva.

Growth, biomass, carbon storage and nutrient distribution in Gmelina arborea Roxb. stands on red lateritic soils in central India

Growth, biomass, carbon storage and nutrient (N, P and K) variations in 1 to 6-year-old chronosequence plantations of Gmelina arborea were studied in three degraded red lateritic sites in central India. Growth parameters (dbh, total height and number of branches) varied significantly due to difference in age and site quality, but tree density showed non-significant variation. Stand biomass ranged from 3.94 (1-year-old) to 53.67 Mgha(-1) (6-year-old) and stand carbon in 6-year-old plantations ranged from 24.12 to 31.12 Mgha(-1) at different sites. Among the tree components, the stem wood accounted for maximum C (56.25% at site 1) followed by branches (19.8% at site 3), roots (18.51% at site 2) and foliage (7.01% at site 3). Mean annual C accretion at 6 years age of plantation was highest in site 3 and it was 0.35, 2.66, 0.965 and 0.87 Mgha(-1) for leaf, stem, branches and roots, respectively. Quantity of nutrients increased with age. Total nitrogen accumulation in 6-year-old stands at the three sites ranged from 212.9 to 279.5 kgha(-1) with a mean annual storage of 238.43 kgha(-1) and total K ranged from 170.8 to 220.5 kgha(-1) with a mean annual storage of 189.93 kgha(-1). Phosphorous accumulation was lowest with a mean storage of 16.75 kgha(-1). The organic carbon and nutrients in the soils improved significantly after 6 years of G. arborea planting. Soil organic carbon increased from 8.46 to 14.02 Mgha(-1) within 6 years. At soil depths 0-20 cm, 21-40 cm and 41-60 cm, available N enhanced by 14.85%, 11.98% and 11.25%, K by 10%, 9.13% and 10.63%, whereas phosphorous declined by 26%, 23% and 20%, respectively. At 6 years, G. arborea stands sequestered 31.37 Mgha(-1) carbon. The nutrient management strategies in relation to carbon accretion in G. arborea stands on degraded lateritic sites are discussed.

Evaluation of Populus deltoides clones under nursery, field and agrisilviculture system in subhumid tropics of Central India

Populus deltoides Bartr., a native of North America, is generally grown in India above latitude 28 °N. One hundred and six clones were evaluated for four years at Raipur situated at 21°12′N latitude and 81°36′E longitude. These were grown on vertisol soil. Based on growth and survival performance in the nursery for two successive years, nineteen clones were selected for field evaluation. The best five clones (G3, G48, 65/27, D121 and S7C1) were planted in an agrisilviculture system at a spacing of 4 × 4 m with soybean grown as an intercrop. After 4 years these clones had an increment of DBH by 66.5 to 77.5% and of height by 42.2 to 78.6% within one year when compared to that observed at 3 years of age. In rank order of growth the best five clones were 65/27 > G3 > D121 > G48 > S7C1. Total biomass varied between 20.9 to 35.8 Mg ha−1 in different clones. Among the tree components, stemwood accounted for 52–61% of the total biomass, followed by branches (20–25%), bark (9–13%) and leaves (7–10%). No significant variation between net primary productivity and photosynthetic efficiency was found in different clones. Soybean productivity decreased as the trees aged, reaching 40.5 to 58.1% in 4-year-old trees.

Productivity of Wheat Under Five Promising Populus Deltoides Clones Under an Agrisilviculture Sysytem

Productivity of wheat were studied under five promising clones (G3, G48, 65/27, D121 and S7C1) of Populus deltoides in agrisilviculture system.. Grain yield of wheat varied from 25.5 to 36.6 q ha-1 and straw yield from 34.9 to 60.7 q ha-1. The yields were highest in sole wheat and reduced under poplar clones from 15 to 30.3% and from 22.7 to 42.5%, respectively. The reduction of wheat yields in different clones was in the order: G3<S7C1<D121<65/27<G48. The study suggested adopting lopping, root hoeing and nutrient management practices in poplar clones G48 and 65/27 to minimize yield losses in wheat under these clones. 0 N latitude. Poplar wood is an important source of plywood, paper pulp and match splint industries. It is usually managed in 6-8 year rotation cycle under agroforestry system. Owing to its rapid growth, high biomass, adoptability, early economic returns and compatability with crops prompted to introduce poplars in agroforestry systems in Chhattisgarh, central India. Poplar was first introduced in the state during 1995 (Puri et al. 2002). Poplar clones are gener- ally leafless (deciduous) during winter (November-February), but some clones do not shed their foliage completely and thus exerts strong competition for light with understorey crops. The presence of such phenological behaviour in poplars could influ- ence the microclimate and affect the physiological processes in intercrops. Further, several poplar clones are believed to be shallow rooted and could cause strong competition with under- storey crops for sharing nutrients. Therefore, the present study was conducted to assess productivity in wheat under different clones of P. deltoides in agrisilviculture system