A Neglected Aspect of Business: Human and Social Capital in the Sri Lankan Tea Plantations

This paper examines idiosyncrasies of tea plantation culture and politics in relation to Sri Lankan national and popular cultural typologies, with special reference to female tea plantation workers. Tea production in Sri Lanka is heavily based on manual labour, and it is the largest industry that provides accommodation for employees and their families. In this paper, it is argued that politico-cultural production relations have dominated labour productivity in tea plantations. Ways in which female workers have been marginalized, through patriarchal politics, ethnicity, religion, education, elitism, and employment are explained. This culture of the plantation community operates negatively with respect to the management agenda. It is also argued that social capital development in tea plantations is important not only for productivity improvement, but also for reasons of political and social obligation for the nation, because migrant plantation workers have been working and living in plantations over 150 years.

Nitrogen cycle of effluent-irrigated energy crop plantations:from wastewater treatment to thermo-chemical conversion processes

This paper reviews nitrogen (N) cycle of effluent-irrigated energy crop plantations, starting from wastewater treatment to thermo-chemical conversion processes. In wastewater, N compounds contribute to eutrophication and toxicity in water cycle. Removal of N via vegetative filters and specifically in short-rotation energy plantations, is a relatively new approach to managing nitrogenous effluents. Though combustion of energy crops is in principle carbon neutral, in practice, N content may contribute to NOx emissions with significant global warming potential. Intermediate pyrolysis produces advanced fuels while reducing such emissions. By operating at intermediate temperature (500°C), it retains most N in char as pyrrolic-N, pyridinic-N, quaternary-N and amines. In addition, biochar provides long-term sequestration of carbon in soils.

Biomass production in short rotation effluent-irrigated plantations in North-West India

This study estimates above-ground biomass in high density plantations of six important semi-arid tree species at Palwal (70 km from Delhi) irrigated with secondary treated sewage water at the rate of 0, 25, 50 and 100% of daily net evaporation potential (EP). In 2.5 y old plantations (plant spacing, 2 m x 2 m for single stem species and 2 m x 1 m for multi-stem species), Melia azedarach showed fairly high biomass production (38.4 t/ha) followed by Ailanthus excelsa (27.2 t/ha). Order of biomass production (kg / tree) was: Eucalyptus tereticornis (24.1) > A. excelsa (21.8) > M. azedarach (12.6) > Populus deltoides clone G 48 (8.3) > Alstonia scholaris (6.6)> Pongamia pinnata (3.7). Survival of plants after 2.5 y ranged from 25.2% in P. deltoides to 71.7% in P. pinnata, and had a significant effect on biomass production per unit area. ANOVA shows that levels of irrigation (0 - 100%) did not have statistically significant effect on plant growth. Correlation between diameter and biomass was found highly significant (p< 0.01) with R2 nearing to 1.

Fertigation potential of domestic wastewater for tree plantations

This study analyses feasibility of using domestic wastewater for fertigation of tree crops. Wastewater samples from different sources in domestic sector were analyzed and evaluated in terms of water quality and quantity. Water is rich in plant nutrients. However, due to possible presence of toxic ions and microbial load, it is recommended that direct use of wastewater for fertigation be limited to timber plantation and energy generation from biomass.

Shade promotes thorn development in a tropical liana, Artabotrys hexapatalus (Annonaceae)

The liana Artabotrys hexapetalus (L.f.) Bhand., which is widely planted in the Tropics and native to African rain forests, produced new reiterations (new leader shoots) normally and after damage induced by Hurricane Andrew (August 24, 1992). In each new orthotropic shoot, there is a gradient in lateral branch structures from basal thorns, to vegetative leafy branches, to distal leafy flowering branches. We noted that reiterations developing in shade had more thorns than similar reiterations developing in full sun. Tents with clear (66% photosynthetically active radiation [PAR]) and shaded plastic film (12%–14% PAR) were placed over nodes when the axillary buds began to expand to produce reiteration shoots. After 2 mo of growth inside the tents and in the open, the types of lateral outgrowths (thorn vs. branch) were recorded. Shoots in spectrally neutral shade (red to far red of full sun) and spectrally altered shade (red to far red of canopy shade) produced significantly more thorns at the lower nodes of the shoots as compared to those in full sun. Shoots in control clear plastic tents were the same as those in full sun. We conclude that the fate of lateral bud development is controlled by irradiance (light level) but not by light quality. Increased thorn production in shade could be advantageous to plants growing in the deep shade of rain forests. Thorns in the self-shaded regions of the plant, and well below the forest canopy, could aid in protection from herbivory and in climbing by acting as hooks.

The developmental responses of papaya leaves to simulated canopy shade

The developmental responses of plants to shade underneath foliage are influenced by reductions in irradiance and shifts in spectral quality (characterized by reductions in the quantum ratio of red to far-red wavelengths, R:FR). Previous research on the influence of shadelight on leaf development has neglected the reductions in R:FR characteristic of foliage shade, and these studies have almost certainly underestimated the extent and array of developmental responses to foliage shade. We have studied the effects of reduced irradiance and R:FR on the leaf development of papaya (Carica papaya L., Caricaceae). Using experimental shadehouses, replicates of plants grown in high light conditions (0.20 of sunlight and R:FR = 0.90) were compared to low light conditions (0.02 of sunlight) with either the spectral quality of sunlight (R:FR = 0.99) or of foliage shade (F:FR = 0.26). Although many characteristics, such as leaf thickness, specific leaf weight, stomatal density, palisade parenchyma cell shape, and the ratio of mesophyll air surface/leaf surface were affected by reductions in irradiance, reduced R:FR contributed to further changes. Some characters, such as reduced chlorophyll a/b ratios, reduced lobing, and greater internode length, were affected primarily by low R:FR. The reduced R:FR of foliage shade, presumably affecting phytochrome equilibrium, strongly influences the morphology and anatomy of papaya leaves.

Correlates of leaf optical properties in tropical forest sun and extreme-shade plants

Thirteens hade-adaptedr ain forest species were comparedw ith twelve sun-adaptedt ropical forest species for correlates to leaf optical properties (described previously in Amer. J. Bot. 73: 1100-1108). The two samples were similar in absorptance of quanta for photosynthesis, but the shade-adaptedt axa: 1) had significantlyl ower specificl eaf weights,i ndicatinga more metabolically efficient production of surface for quantum capture; 2) synthesized less chlorophyll per unit area; and 3) used less chlorophyll for capturing the same quanta for photosynthesis. The anatomical features that best correlate with this increased efficiency are palisade cell shape and chloroplast distribution. Palisade cells with more equal dimensions have more chloroplasts on their abaxial surfaces. This dense layer of chloroplasts maximizes the light capture efficiency limited by sieve effects. The more columnar palisade cells of sun-adapted taxa allow light to pass through the central vacuoles and spaces between cells, making chloroplasts less efficient in energy capture, but allowing light to reach chloroplasts in the spongy mesophyll. Pioneer species may be an exception to these two groups of species. Three pioneer taxa included in this study have columnar palisade cells that are extremely narrow and packed closely together. This layer allows little penetration of light, but exposure of the leaf undersurface may provide illumination of spongy mesophyll chloroplasts in these plants.

Simulating Forest Shade to Study the Developmental Ecology of Tropical Plants: Juvenile Growth in Three Vines in India

Both light quantity and quality affect the development and autoecology of plants under shade conditions, as in the understorey of tropical forests. However, little research has been directed towards the relative contributions of lowered photosynthetic photon flux density (PPFD) versus altered spectral distributions (as indicated by quantum ratios of 660 to 730 nm, or R:FR) of radiation underneath vegetation canopies. A method for constructing shade enclosures to study the contribution of these two variables is described. Three tropical leguminous vine species (Abrus precatorius L., Caesalpinia bondicela Fleming and Mucuna pruriens (L.) DC.) were grown in two shade enclosures with 3-4% of solar PPFD with either the R:FR of sunlight (1.10) or foliage shade (0.33), and compared to plants grown in sunlight. Most species treated with low R:FR differed from those treated with high R:FR in (1) percent allocation to dry leaf weight, (2) internode length, (3) dry stem weight/length, (4) specific leaf weight, (5) leaf size, and (6) chlorophyll a/b ratios. However, these plants did not differ in chlorophyll content per leaf dry weight or area. In most cases the effects of low R:FR and PPFD were additional to those of high R:FR and low PPFD. Growth patterns varied among the three species, but both low PPFD and diminished R:FR were important cues in their developmental responses to light environments. This shadehouse system should be useful in studying the effects of light on the developmental ecology of other tropical forest plants.