The Fine Structure of Bamboo Fibres: I. OPTICAL PROPERTIES AND X-RAY DATA

Following the recent work on wood tracheides and sisal fibres,a detailed investigation has been made of the fine structureof a wide variety of bamboo fibres. A combination of X-ray analysis,measurement of refractive indices in longitudinal view and ofphase differences in transverse section, has presented a completepicture of cellulose chain orientation. The wall of bamboo fibresis many layered. An outermost, thin layer is composed of cellulosechains making an angle of 35° to cell length and this isfollowed by other, inner layers where the angle steadily decreasesfrom outer to inner layers, first to about 20° and thento about 10°. These layers are separated by thicker layers,dark in transverse section between crossed nicols, in whichthe angle is seldom more than 5–6°. These are averagefigures. The results show most clearly that each angle, , varieswith the fibre length, L, in such a way that the longer cellshave steeper spirals in harmony with a relation of the typeL=A+Bcot already proposed for wood tracheides.     

Species Structure, Dry Matter Dynamics and Carbon Flux of a Dry Tropical Forest in India

Species composition, plant biomass and net primary productivitywere studied on three sites of a dry tropical forest The forestwas characterized by small structure with 38–10.4 m2 ha^–1tree and 3 1–7 8 m² ha^–1 shrub basal cover Speciesdiversity was highest for the mid-slope site while the concentrationof dominance was greatest for the hill-top stand The beta diversitywas 3 1 Total standing crop of vegetation averaged 66 98 t ha^–1with 46 70 t ha^–1 in the tree layer, 13.97 t ha^–1in the shrub layer, 0.35 t ha^–1 in the herb layer, 2 83t ha^–1 in the litter layer and 3 13 t ha^–1 in fineroots Of the total annual litterfall (4 88–6.71 t ha^–1),69% was accounted for by leaves and 31% by non-leaf matter Netprimary production (NPP) ranged between 11 3 and 19 2 t ha^–1year^–1, to which the contributions of trees, shrubs andherbs averaged 72, 22 and 6%, respectively Contribution of rootsto NPP was substantial and ranged from 2 9 to 5 3 t ha^–1year^–1 A total of 83% of vegetation carbon was storedin the above-ground plant parts while the above-ground NPP wasresponsible for 72% of the total carbon input into the systemThe contribution of foliage, herbaceous vegetation and fineroots to carbon turnover was disproportionately larger comparedto their share in the total standing crop Carbon budgeting indicatedthat the forest was an accumulating system, over at least theshort term Dry tropical forest, biomass, litterfall, net primary production, carbon budget, carbon flux     

Influence of Foliar Application of S-Triazine Compounds on Fresh Weight, Dry Weight, Chemical Composition, and Enzymatic Activity of Pea and Sweet Corn Seedlings

We applied 5 and 2 parts/10⁶ of simazine, atrazine, igraii,GS-14254, propazine, prometryne, prometone, or ametryne to thefoliage of 3-week-old seedlings of peas (Pisum sativum L., cv.Perfected Freezer) and sweet corn (Zea mays L.f cv. Iochief)growing under greenhouse conditions on perlite and suppliedwith complete Hoagland's solution. The results indicated a highercontent of protein in the treated leaves than in the leavesof untreated controls. (7 to 35 per cent for pea seedlings and0 to 50 per cent for corn seedlings.) Treated leaves had significantlyless starch and sugars than the controls. The activities ofnitrate reductase (NRase) and glutamic-pyruvic transaminase(transaminase) were enhanced, but there was no significant effecton ribonuclease (RNase).     

Lipid histochemistry of the epidermis of Natrix piscator during its sloughing cycle

The lipid histochemistry of the scale and hinge epidermis of the chequered water snake, Natrix piscator , throughout the sloughing cycle, has been described. The presence of comparatively high concentrations of phospholipids in the mesos layer and a-layer, in comparison to neutral lipids, has been associated with a permeability barrier to transcutaneous water flux. Free fatty acids, present in almost all epidermal layers and in eosinophilic granular cells, may protect the epidermis from bacterial and fungal attacks. Cholesterol, in addition to phospholipids, in various keratinized layers, is assumed to be derived from membranous structures of epidermal cells and is regarded as a stabilizer of the phospholipids in membranes.     

Storage and Flux of Nutrients in a Dry Tropical Forest in India

Storage and flux of N, P, Ca, K and Na were studied in a drytropical forest The nutrient concentrations in different growthforms were in the order herb > shrub > tree, whereas thestanding state of nutrients followed the order tree > shrub> herb The total storage (kg ha^–1) in vegetation amountedto 567 N, 37 P, 278 Ca, 256 K and 46 Na The share of above-groundparts in vegetation storage was 82 % for N, 83 % for P, 76 %for Ca, 85 % for K and 79 % for Na From 56 to 71 % of foliarN, P and K was withdrawn during senescence Nutrient input (kgha^–1 year^–1) from the vegetation (above-ground +below-ground) to forest floor amounted to 115 N, 8 P, 62 Ca,38 K and 10 Na compared to total net annual uptake (kg ha^–1)of 143 N, 10 P, 78 Ca, 52 K and 12 Na, indicating marginal accumulationin the system Fine roots were as important a pathway of nutrientreturn as leaf litter Turnover rate and turnover time for differentnutrients on the forest floor ranged, respectively, between72 and 83 % and 12 and 1 39 years Dry tropical forest, nutnent concentration, standing state, uptake, internal cycling, turnover