Chapter – VI RESULTS AND DISCUSSION 87 6. RESULTS AND DISCUSSION The work has been conducted season wise collected sample of plant materials i.e. selected Tea cultivars grown at different agro-soil zones, agro-climatic conditions along with processed and unprocessed tea samples. All samples were collected from different tea gardens situated at Dooars, Terai, and Darjeeling Hills of North Bengal. 6.1 SURVEY 6.1.1 Pilot study for collection of plant materials Pilot survey was conducted from the data source of tea gardens of Terai, Dooars and Darjeeling hills to document for the distribution of Tea plant varieties and their ages. This survey was essential to know growing conditions of tea clones and on the basis of yield and standard quality along with commonly used variety was only selected for these experiments. From the Table 6.1 it was observed that most of the tea gardens of Terai, Dooars and Darjeeling Hills cultivated standard and yield, quality of tea varieties i.e. TV1(Accession No. 6202), TV20(Accession No. 6203), TV26(Accession No. 6204), TV29(Accession No. 6205), TV30(Accession No. 6206), Tingamara(Accession No. 6207), Dangri Manipuri(Accession No. 6208), Sundaram (B/5/63, (Accession No. 6209) Tinali 17(Accession No. 6210), Takda 7, 8. (Accession No. 6211) Only these 10 selected Tea varieties were investigated during three harvest season, March, June and December in 2006 to 2010. 6.1.2 Soil sampling Soil samples were collected from three different agro-climatic areas of North Bengal and samples also were collected from adjacent barren land, multi crops system to document the soil degradation pattern due to tea monoculture. Soil (top and sub soil with 0-22.5 cm and 22.5-45 cm depth respectively) and composite soil were prepared as per the method of Misra et al., (2009). The samples were processed for physicochemical analysis viz. pH, electrical conductivity, soil texture, moisture contents, organic carbon, available form = of nitrogen, potash as K2O, phosphorus as P2O5, Chloride and sulphur as SO4 (Jackson, 1973). 88 Table 6.1 Tea Research Association (TRA) certified clones cultivated in North Bengal Region and ages of tea Standard (with average yield and Yield (with very high yield and Quality (with very high quality Plants quality) average quality) and average yield) TV1, 14, 16, 17, 18, 20, 24, 27, 28, TV 22, 23, 25, 26, 29, 30, Terai (20-50 years) TV 21, Tinali 17, Takda7,8 Tingamara, Dangri Manipuri Sundaram (B/5/63) TV1,14, 16, 17, 18, 20, 24,28, TV 22, 23, 25, 26, 29, 30, Dooars (20-50 years) TV 21, Tinali 17, Takda7,8 Tingamara, Dangri Manipuri Sundaram (B/5/63) TV 1,14,20,26,29,30, TRA/AV 2, BB157, SKIM 1, RR17/144, P1258, HV 39, RR4/5, TV19, CP 1, BB688, 777, T145, Tinali 17, Darjeeling (20-50 years) T78, 135, 383, Tingamara, Dangri Sundaram (B/5/63) Takda7,8 Manipuri 89 6.1.3 Record of angiosperms (shade trees and weeds) from tea gardens Tea plants occupy the lower stratum in such artificial plant community and are generally not mixed with any other species. Shade trees in tea gardens form an open canopy and this stratum is usually a mixed community. 24 species of such trees recorded from the areas under study have been presented in Table 6.2. Many of these plants are deciduous trees and their leafless period has also been recorded in this table. For the selection of shade tree species apart from soil conditions some other factors are also need to be considered like: (i) shape of the canopy, (ii) economic life, (iii) pest and disease resistance, (iv) hardness, (v) depth of root system, and (vi) foliage retention (Singh, 2005). These factors have definite bearing on the management of the shade trees and help to determine spacing, amount of lopping required and rotation. The more resistant the trees to pests, diseases and storm damage, the easier will be their maintenance. A deep rooted system of shade trees is desirable as it can explore the soil below the rhizosphere depth of the tea roots. However, it should be noted that a high water table will restrict the root development of shade trees. Table 6.2 also shows the leafless period of different recorded shade trees. Rejected leaves, after receiving irrigation water or few showers of rain, got decomposed and enriched the soil. Further, it reduces heat of the soil, loss of soil moisture and improves the physical properties of soil. On the basis of leafless period and the agro-climatic conditions, the intimate mixtures of shade trees are helpful. This type of mixtures for Dooars and Terai may be Dalbergia sissoo, Adenanthera pavonina, Albizzia odoratissima, Albizzia lebbek and Indigofera teysmanii. It is well established fact that in the plains of North East India, provision of some form of shade by planting shade trees is a must for better growth and production of tea. In the study areas 24 species of shade trees has been recorded and the specimen sample were deposited at Department of Botany, University of North Bengal. 90 Table 6.2 Shade Tree species in different soil [DSR = Dry, Sandy and Riverine] Name of shade trees [Acc no of Family Soil type Land type Leafless period Used in submitted herbarium specimens] Acacia auriculiformis A. Cunn. ex DSR, Swampy, Fabaceae Plains - Plantation Benth. [Accession No. 6126 ] Moist, Alkaline Denuded hill slope, Acacia catechu (L.f.) Willd. [Accession Plantation, Fabaceae DSR Land slide prone hill - No. 6127 ] Nursery slope Acacia lenticularis Benth. [Accession Plantation, Fabaceae DSR, Moist Denuded hill slope March to April No. 6128] Nursery Adenanthera pavoniana L. [Accession January to Plantation, Fabaceae DSR, Alkaline Denuded hill slope No. 6129] March Nursery Albizia chinensis (Osbeck) Merril. January to Fabaceae DSR, Alkaline Plains Plantation [Accession No. 6130 ] March Albizia lebbeck (L.) Benth. [Accession Plantation, Fabaceae DSR, Alkaline Plains January to April No. 6131 ] Nursery Albizia moluccana Miq. Accession No. Fabaceae DSR Plains March Plantation 6132 ] Albizia odoratissima (L.f.) Benth. December to Plantation, Fabaceae DSR, Alkaline Denuded hill slope [Accession No. 6133] February Nursery Albizia procera (Roxb.) Benth. Fabaceae Moist, Alkaline Plains February to May Plantation [Accession No. 6134 ] Azadirachta indica Juss. [Accession No. January to Meliaceae DSR Plains Plantation 6135 ] March Butea monosperma (Lam.) Kuntz. December to Fabaceae Swampy Plains Plantation [Accession No. 6136 ] February Cajanus cajan (L.) Millsp. [Accession Fabaceae DSR Plains - Nursery No. 6137 ] Cassia siamea Lam. [Accession No. Plains, Denuded hill Plantation, Fabaceae Moist - 6138 ] slope Nursery 91 Table 6.2 Shade Tree species in different soil [DSR = Dry, Sandy and Riverine] Name of shade trees [Acc no of Family Soil type Land type Leafless period Used in submitted herbarium specimens] Dalbergia assamica Benth. [Accession December to Fabaceae DSR Denuded hill slope Plantation No. 6139 ] March Dalbergia sericea G.Don. [Accession December to Plantation, Fabaceae DSR Denuded hill slope No. 6140 ] March Nursery Dalbergia sissoo DC. [Accession No. DSR, Swampy, Plains, Land slide prone December to Plantation, Fabaceae 6141 ] Alkaline hill slope February Nursery Derris robusta Benth.[Accession No. December to Plantation, Fabaceae DSR Denuded hill slope 6142] February Nursery Gmelina arborea Roxb. [Accession No. Plantation, Verbenaceae DSR, Moist Denuded hill slope February to May 6143] Nursery Grevillea robusta Cunn. ex R. Br. Proteaceae DSR Denuded hill slope - Plantation [Accession No. 6144 ] Indigofera teysmanii Miq. [Accession January to Plantation, Fabaceae DSR, Moist Denuded hill slope No. 6145 ] March Nursery Melia azedarach L. [Accession No. DSR, Swampy, Land slide prone hill Meliaceae January to May Plantation 6146 ] Moist, Alkaline slope Millingtonia hortensis L.f. [Accession January to Bignoniaceae Swampy Plains Plantation No. 6147 ] March Neolamarkia cadamba (Roxb.)Boss. Plantation, Rubiaceae Moist Plains - [Accession No. 6148 ] Nursery Trema orientalis (L.) Bl. [Accession Ulmaceae DSR Plains - Plantation No. 6149] 92 Table 6.3 Common weeds grown in Tea gardens of Darjeeling, Terai and Dooars Seed forming Name (Accn. no.) Vegetative period Flowering period period Ageratum conyzoids L. [Accession No. 6177 ] March to June July to October July to December Ageratum haustonianum Miller [Accession No. 6178] March to June June to December June to January Amranthus spinosus L. [Accession No. 6175 ] May to August September to December September to December Arundinella benghalensis (Spreng.) Druce [Accession No. 6150 ] April to May July to September August to September Axonopus compressus (Sw.) P. Beauv. [Accession No. 6151] April to May May to September June to October Borreria alata (Aubl.) DC. [Accession No. 6152 ] April to august September to November October to November Centella asiatica (L.) Urban.[Accession No. 6176] February to April June to October July to November Cynodon dactylon (L.) Pers.[Accession No. 6153 ] February to September March to November April and November Cyperus pilosus Vahl [Accession No. 6154 ] April to May May to September July to September Cyperus rotundas L. [Accession No. 6155 ] February to March March to July May to August Digitaria ciliaris L. [Accession No. 6171 ] March to May June to September July to September Digitaria sanguinalis (L.) Scop.[Accession No. 6156 ] March to April May to September June to October Eragrostis tenela (L.) R. Br. ex Roem. & Schult. [Accession No. February to June June to August July to August 6170 ] Eupatorium odoratumL. [Accession No. 6157] May to October November to January December to January Fimbristylis miliacea (L.) Vahl [Accession No. 6158 ] April to June June to September December to January Imperata cylindrica (L.) Raeus. [Accession No. 6159 ] June to September April to May May to November Justisia prostrata Gamble [Accession No. 6173 ] June to November December to March January to March 93 Table 6.3 Common weeds grown in Tea gardens of Darjeeling, Terai and Dooars Seed forming Name (Accn.