Abstract

Background: Parrotiopsis Jacquemontiana -(Decne.) Rehder is regarded as an important natural resource almost throughout the world but relatively little is known about the within-tree variability of the anatomical characteristics of its wood.
Methods: For this purpose three sites were selected and from each site three trees were felled and five discs were extracted from base upto merchantable top of the each tree, equally spaced along vertical direction. The wood anatomical features viz. fiber length, fiber diameter, fiber wall thickness, varied significantly from different positions of trees.
Conclusion: Also the derived wood properties like Runkel ratio, Slenderness ratio, Luce’s shape factor were evaluated from wood anatomical features as these parameters are directly related to industrial utility of wood especially, paper quality.

Introduction

Wood is unique among the world’s important raw materials virtually used by every one in diverse ways. It is a remarkable material with a variability and flexibility that makes it useful for many kinds of products. Wood is known to have been used for various structural and other purposes since the dawn of history and has been serving mankind even in modern times with enormous technological know how. It is the fifth most important product of the world trade. The complex make up of wood (cellulose, hemicelluloses, lignin and pectin) makes it an ideal raw material for what could replace the petro-chemical industry, in providing not only plastic and all kinds of chemical products, but also food and textile products²⁸. The durable properties of wood vary considerably from species to species often within the species, and selection of wood depends upon the conditions it is required to endure.

This variability arises from the dimensions of its anatomical structures like vessel elements, fibers, rays etc in both vertical i.e. from base up to the top of the tree and in radial direction from pith (inside) to the bark (peripheral) of tree respectively. The variability of wood anatomical features directly or indirectly has a bearing on the efficient use of wood for different end uses. Keeping in view the importance of wood anatomy in predicting the suitability of different woods for their varied utility purposes, the present work is an attempt to elucidate wood anatomical variation patterns within and among trees/shrubs of Paratiopsis jacquemontiana.

It is a large deciduous gregarious shrub/tree 6-20 feet high, found throughout Kashmir valley between 3800 to 8500 feet above sea level except on eastern slopes of Pirpanjal forest division from Gulmarg to Kulgam. It is an integral part in the living system of Kashmiries. Owing to the severe winter of Kashmir valley; the Kangries (made by weaving young twigs of Parrotiopsis jacquemontiana around earthen fire port), helps to Kashmiries, keep themselves and their children warm during prolonged winters from November to March. Charcoal made of Parrotiopsis jacquemontiana is considered of best grade. Its wood is used for making of tool handles were durability and strength is needed. Besides the wood is rich and best source of pulp for manufacturing of paper and plywood³⁶.

Materials and Methods

Source of Material

The present study was carried out on Parrotiopsis jacquemontiana, a hardwood tree/shrub with deciduous type of habit, belonging to family Hammamaladiaceae from natural provenances of Kashmir Himalaya for its anatomical characteristics. The sites which were surveyed are Khrew, Pampore, Ladhoo, Pulwama, Shopian, Ahrabal, Charsoo, Anantnag, Qaimoh, Budgam, Brenward Surasyar, Gowharpora, Shalimar, Darbagh, Naranag, Batpora, Habbak. Out of the sites, three were selected for the wood anatomical characteristics viz., Khrew (site-1), Surasyar (site-2), Shopian (Site -3).

These sites were selected on the basis of the following criterions:-

A. Accessibility of sites

B. Availability of the material

1. The geographical locations along with other characteristics of the selected sites are summarised in the Table -1.

Three trees of each species were felled and 10 cm thick discs were cut at five positions equally spaced along the vertical directions from base up to the merchantable top of tree. These were named as DI, DII, DIII, DIV and DV from base up to the top respectively. From these discs, in order to study a vertical variation, a disc wedge was removed at any cardinal directions⁷. The wedge was further divided into three parts as per locations viz., inner (Pith), middle and outer (peripheral). All samples were studied for wood element dimensions and variations within tree/shrubs and among replicates at each site²⁵.

Maceration

Maceration was done as per Jeffery’s method¹⁶ for all the samples studied. In this method, small slivers of wood were taken from the samples collected into the test tube and then filled with 10% chromium trioxide and 10% nitric acid and left for one to several days at room temperature and the process was hastened by heating up to approximately 60⁰C for few minutes. After that, the material was thoroughly washed with distilled water till traces of the acid were removed. The mixture was teased/shaken thoroughly to separate the wood elements and stained with 1% Safranin and mounted in glycerine on microscopic slides.

Wood element measurements

The measurements/dimensions of fibers were done with the help of ocular-stage micrometry. Twenty-five measurements were made from unbroken fibers for diameter, wall thickness and length.

The derived wood properties of Runkel ratio, Luce’s shape factor, and Slenderness ratio were calculated from measurements of the fiber morphology as per²³.

Luce’s shape = (fiber diameter²-fiber lumen diameter²) / factor (fiber diameter² + fiber lumen diameter²) Statistical analysis.

The data collected for present study was statistically analyzed by using Sigma Plot 12.0 statistical software (SPSS. Chicago. IL.USA) and Minitab 11.0 for windows.

Results

(a) Fiber length

In Parrotiopsis jacquemontiana, the fiber length varied significantly among the sites. The average fiber length ranged from 923.36 µm in site III (Shopian) to 1169.33 µm in site II (Surasyar) (Table 2a). The fiber length variation within disc i.e., from inner to outer (inner, middle and outer); within tree i.e., from base upto merchantable top of tree (DI, DII, DIII, DIV and DV) and among sites (site I, site II, site III) is statistically significant. But, the interaction of site, disc and location i.e. site × disc, site × location, disc × location and site × disc × location does not show any statistical significance (Table 2b).

(b) Fiber diameter

In Parrotiopsis jacquemontiana, the mean fiber diameter varied significantly among the sites. The mean fiber diameter ranged from 14 µm in site III (Shopian) to 17.18 µm in site I (Khrew) (Table 3a). The interaction of site, disc and location i.e. site * disc, disc * location and site * disc * location does not show any statistical significance except site * location interaction which is statistically significant (Table 3b).

(c) Fiber wall thickness

The fiber wall thickness in Parrotiopsis jacquemontiana varied significantly among the sites. The average fiber wall thickness ranged from 4.14 µm in site III (Shopian) to 5.87 µm in site I (Khrew) (Table 4a). Besides these, the interaction of site, disc and location i.e. site * disc, site * location, disc * location and site * disc * location does not show any statistical significance (Table 4b). Hence statistically there is no effect of these interactions on the dimensions of fiber wall thickness.

Derived wood properties of Parrotiopsis jacquemontiana.

Runkel ratio

In Parrotiopsis jacquemontiana, the Runkel ratio varied significantly among the sites (Table 5a) from 1.51 in site I to 2.28 in site III (Table 5). In all the discs, among the sites three locations i.e. inner, middle and outer are statistically significant with one another within the discs (Table 5a).

Luce^,s shape factor

In Parrotiopsis jacquemontiana, the Luce’s shape factor varied significantly among the sites from 0.70 in site III to 0.84 in site I (Table 5b). In all the discs, among the sites, three locations i.e. inner, middle and outer are statistically significant with one another within the disc (Table 5b).

Slenderness ratio

In Parrotiopsis jacquemontiana, the Slenderness ratio varied significantly among the sites from 56.76 in site I to 71.09 in site II (Table 5c).

Discussion

Fiber morphology

Fiber length varied significantly among the sites in presently studied species of Parrotiopsis jacquemontiana (923.36 µm to 1169.33 µm), Previous reports on the variation of fiber length among sites were reported by many authors^{2227671829382125}. Thus the present results are in agreement with the above said authors. Cheng and Bensend⁸ Einspahar et al.,¹² Peszlen²⁶ reported that fiber length is under genetic control. On the contrary in the present study, the pattern of fiber length and the dimensions of anatomical characters varied with site for the same clone, which is indicative of overshadowing of genetic control by environmental factors on fiber dimensions.

Cell size and relating dimensions of fibers have a major influence on the quality of paper and pulp products as well as solid products⁹²¹ . For pulp and paper production, species with higher lengths are preferred since a better fiber net is achieved, resulting in higher resistance of the paper. The existence of significant variation between sites for the fiber morphological traits indicates good opportunities for exploitation of these sites and superior trees among them for specific end uses.

Fiber morphological parameters, such as fiber length, diameter, and wall thickness were found to be significantly influenced by their radial positions within tree. Fibers in the pith region were shorter, thin walled and less wide in diameter as compared to those at periphery, there being a gradual increase radially from centre.

Most reports on radial pattern of variation in hardwoods dealing with fiber dimensions agrees that fibers near the centre of the tree are shorter, thin walled and narrow in diameter as compared to periphery fibers. To quote some authors in favour are Hejnowicz and Hejnowicz¹⁵, Carvalho⁵, Denne¹¹, Bhat and Karkkanian³, Furukawa et al.,¹³ Tomazello-Filho³⁵, Stringer and Olson³⁴, Sennerby-Forse³², Bhat et al.,², Peszlen²⁶, Kauba et al.,¹⁹ Adamopoulos and Voulgaridis¹, Marsoem et al.²⁰

The increase of fiber length from pith to periphery could be explained on the basis of the increase in length of cambial initials with increasing cambial age from pith to periphery¹⁴¹⁸.

There is an increase in fiber dimensions upto certain height and thereafter decrease in it. Same pattern was also observed by Bisset and Dadswell⁴, Carvalho⁵, Sardinha and Huges³¹, Wilkes³⁷, Bhat et al.² Jorge¹⁷, Jorge et al.¹⁸ in hardwood species. The decrease of wood fiber dimensions towards the top was also described by Stringer and Olson³⁴ for Robinia pseudoacacia L.³⁰ for Eucalyptus globulus Labill. and⁷ for Populus deltoides Bartram. ex Marsh. This increase in fiber dimensions from base up to certain height and there after decreasing upto top of tree in vertical direction is due to the differential proportion of juvenile wood in trees³⁹.

Derived wood properties (Ratios and Factors)

Different types of ratios such as Runkel ratio, Luce’s shape factor and Slenderness ratio were determined from the respective basic data related to fiber morphology. These ratios are important particularly for determining the suitability of a particular material for pulping and paper making.

Runkel ratio is obtained by dividing double wall thickness by fiber lumen diameter. The approximate limits of Runkel ratio appears to be from 0.25 to 1.5³³ for a species. Dadswell and Wardrop¹⁰ suggested Runkel ratio to be less than 1 which can produce pulp of reasonable quality, while²⁴ suggested that Runkel ratio is significantly related to pulp yield. The values obtained in this investigation shows significant variation between sites for Runkel. Among the three sites site II (Surasyar) can produce reasonable quality of pulp with good conformability and fiber to fiber contact followed by Site I (Khrew) and Site III (Shopian).

Slenderness ratio (fiber length/fiber diameter) showed significant differences among the sites in Parrotiopsis jacquemontiana, higher the ratios, greater will be the expected fiber flexibility that will give better tensile and tear property to the paper. In present study the highest values of slenderness ratio are present in site II (Surasyar) followed by site III (Shopian) and site I (Khrew). Hence among the sites, site II (Surasyar) with highest values of Slenderness ratio, the wood from this site would be suitable for paper having higher flexibility, hence better tensile and tear property, followed by site III and site I respectively

Luce’s shape factor an important derived wood property obtained by equation (fiber diameter²- fiber lumen diameter²)/(fiber diameter² + fiber lumen diameter²) (Oshima et al. 2005) and is directly related to the paper sheet density²⁴. In the present study the highest values of Luce’s shape factor are found in site II (Surasyar) followed by site I (Khrew) and site III (Shopian). Hence among the sites; site II (Surasyar) with highest values of Luce’s shape factor, possess the highest values of paper sheet density by, followed by site I and site III respectively.

Conclusion

In the present study fiber length varied significantly among the sites, which is indicative of overshadowing of genetic control by environmental factors on fiber dimensions. The existences of significant variation among sites for the fiber morphological traits indicate good opportunities for exploitation of these sites and superior trees among them for specific end uses. For pulp and paper production, species with higher lengths are preferred since a better fiber net is achieved, resulting in higher resistance of the paper. Also the derived properties of wood like Runkel ratio, Slenderness ratio and Luce’s shapes factor varied among the sites as these ratios are important particularly for determining the suitability of a particular material for making pulp and paper.