Traditional medicinal plants in Mizoram, India

In rural societies of Mizoram, India, traditional methods of treatment are followed in the majority of the populace. Information on 135 plant species from 122 genera and 65 families is presented here.     

Litter production and decomposition dynamics in moist deciduous forests of the Western Ghats in Peninsular India

A field study was conducted in the moist deciduous forests of the Western Ghats (India) to test the following three hypotheses: (1) Litter production in tropical forests is a function of the floristic composition, density, basal area and disturbance intensity; (2) Decay rate constants of tropical species is an inverse function of the initial lignin/nitrogen ratio; (3) Decomposition rates in tropical forests are faster than temperate forests.

Litter fall was estimated by installing 63 litter traps in the moist deciduous forests of Thrissur Forest Division in the Western Ghats at three sites. Litter fall followed a monomodal distribution pattern with a distinct peak during the dry period from November–December to March–April.Dillenia pentagyna, Grewia tiliaefolia, Macrosolen spp.,Xylia xylocarpa, Terminalia spp.,Lagerstroemia lanceolata, Cleistanthus collinus, Bridelia retusa, andHelicteres isora were the principal litter producing species at these sites. The annual litter fall ranged from 12.18 to 14.43 t ha⁻¹. Structural attributes of vegetation such as floristic composition, basal area, density and disturbance intensity did not directly influence litter fall rates.

Leaf litter decay rates for six dominant tree species were assessed following the standard litter bag technique. One hundred and eight litter bags per species containing 20 g samples were installed in the forest floor litter layer at the same three sites selected for the litter fall quantification exercise. The residual litter mass decreased linearly with time for all species. In general, less disturbed sites and species adapted to higher nitrogen availabilities exhibited relatively higher decay rate coefficients (k). The rapid organic matter turnover observed in comparison with published temperate forest litter decay rates confirms that tropical moist deciduous forest species are characterised by faster decomposition rates.

Mean concentrations of N, P and K in the litter were profoundly variable amongst the dominant species. Initial nitrogen content of the leaf litter varied from 0.65 to 1.6%, phosphorus from 0.034 to 0.077% and potassium from 0.25 to 0.62%.C. collinus, an understorey shrub consistently recorded the lowest litter concentrations for all nutrients. The overriding pattern is one of higher nutrient levels in the overstorey leaf litter and lower concentrations in the understorey litter. Furthermore, as decomposition proceeded, the nitrogen concentration of the residual biomass increased.     

Root distribution pattern of the wild jack tree (Artocarpus hirsutus Lamk.) as studied by 32P soil injection method

Root distribution of the wild jack tree (Artocarpus hirsutus) was determined by selective placement of ³²P at various depths and lateral distances from the tree, in Kerala, India. In eight-and-a-half-year-old trees growing on a lateritic site, absorption of ³²P from a lateral distance of 75 cm and 30 cm depth was much greater than from 150 and 225 cm lateral distance and 60 and 90 cm depth. Root activity declined with increasing depth and lateral distance. Most of the physiologically active roots were concentrated within a radius of 75 cm and 30 cm depth, although the tap root might reach even deeper. Possibly, surface accumulation of feeder roots may cause considerable overlap of the tree and crop root zones in intercropping situations. However, as the tree roots seldom extend beyond 2.25 m laterally from the trunk, the effect of overlapping root zones and the associated competitive effects may not be a serious problem for intercropping during the first few years (<10 years after planting) of tree growth.     

A study of the potential of hedgerow intercropping in semi-arid India using a two-way systematic design

The potential of hedgerow intecrropping with Leucaena leucocephala was explored on vertic Inceptisols over 4 years at ICRISAT Center, Patancheru, India. The study was conducted using a systematic layout involving different alley widths ranging from 1.35 to 4.95 m and with varying distances between hedge and crops. The alleys were cropped with alternate rows of sorghum and pigeonpea. Hedges composed double Leucaena hedgerows 60 cm apart were periodically harvested for fodder. Sole crops of all components and a sorghum/pigeonpea intercrop were included in all four replications of the study.Starting in the second year, Leucaena was progressively more competitive to annual crops, causing substantial yield reduction. Competition (primarily for moisture) was most severe in narrow alleys and was greatest on pigeonpea.The growth of Leucaena was not sufficient to compensate for reduced crop yields. Land equivalent ratios (LERs) calculated on the basis of grain yield of crops and Leucaena fodder yields showed that hedgerow intercropping (HI) was advantageous over sole crops only during the first two years using wide alleys, but disadvantegeous in the last two years. LERs calculated on the basis of total dry matter indicated only a small advantage for HI (13–17 percent) over sole crops in wider (>4 m) alleys. Average returns per year from HI exceeded those of the most productive annual crop system (sorghum/pigeonpea intercropping) by 8 percent in 4.05 m alleys, and by 16 percent in 4.95 m alleys. Fodder production during the dry season was 40 percent of the annual total in these alley widths. Thus hedgerow intercropping at 4–5 m alley width is not very attractive for farmers in semi-arid India, which has 600–700 mm of annual rainfall. There is a need to examine the potential of HI in wider alleys. The merits and limitations of the systematic design are discussed.     

Antimicrobial activity of Memecylon malabaricum leaves

The petroleum ether, chloroform and methanol extracts of Memecylon malabaricum leaves were tested for antimicrobial activity. Only methanol extract has shown activity against bacteria both Gram (+) and Gram (-), and fungi.     

Antibacterial activity of Mappia foetida leaves and stem

Successive petroleum ether, chloroform and methanol extracts of Mappia foetida leaves and stem were tested for their antibacterial activity. The methanol fractions were found to be most effective against all the tested organisms.     

Development of Melampsora ciliata rust on nursery‐grown poplars in north‐western Himalayas

Development of leaf rust (Melampsora ciliata) in different species, hybrids and cultivars of poplar (Populus spp.) was studied in nursery‐grown plants. Five different criteria were used to assess the disease development. The mean disease index on 10 August was 9.4% which increased to 70.0% on 10 October. The lowest disease index (5.5%) was recorded in P. yunnanensis whereas the maximum was recorded in P. × euramericana‘Rubra‐Poiret’ (59.5%). The apparent infection rate per unit per day was highest in P. nigra × P. trichocarpa (9.7 × 10^–2) whereas the minimum occurred in P. maximowiczii × P. berolinensis‘Oxford’ (3.3 × 10^–2). The area under the disease progress curve was a maximum in P. × euramericana‘Rubra‐Poiret’ (26.7) and a minimum in P. yunnanensis (1.6). Complete defoliation by the first half of October occurred in P. nigra × P. trichocarpa, which also had the maximum apparent infection rate and area under the disease progress curve. Inoculum production was highest in P. nigra × P. trichocarpa and lowest in P. maximowiczii × P. berolinensis‘Oxford’.     

Status of floor vegetation under some monoculture and mixculture plantations in North India

A study conducted to assess the floor vegetation shows the presence of 17 species underPopulus deltoides in comparison to 28, 29 and 35 underAlbizia lebbeck, Dalbergia sissoo and mix-culture plantations, respectively. Further, the biomass and density of floor vegetation is considerably reduced underP. deltoides compared to other plantations. In addition, the indices for species richness, evenness, dominance and diversity are also reduced underP. deltoides showing some inhibitory mechanism being operative under these plantations. Based on available literature, allelopathy is speculated to be responsible for this reduction.     

Bacteria wilt of Casuarina equisetifolia in India

Pseudomonas solanacearum (Smith) was consistently isolated from the wilted plants of Casuarina equisetifolia. The isolate gave positive reaction to oxidase, catalase and gas production from nitrate and negative reaction for arginine dihydrolase and acid was produced from various carbohydrates. Wilt produced on tomato, egg plant and capsicum indicated that the pathogen belongs to Race I and Biovar III of P. solanacearum which is a new record from India.     

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