Taking tea is an integral part of social life in Pakistan. The tea consumed in the country is imported making Pakistan the second largest importer after United Kingdom. The consumption is increasing day by day mainly due to the rapid increase in population. Keeping in view the alarming situation, it seems imperative to develop tea industry at indigenous level to avert the continuous drain on meager foreign exchange resources of the country.
Tea (Camellia sinensis L.) is a unique crop, as its cultivation and harvesting do not fit in to any typical cropping pattern. It is a perennial, evergreen shrub and its tender leaves and a bud are plucked for processing the black or green tea. It is a crop of wide adaptability and grows in a range of climates and soils in various parts of the world.
Fortunately Pakistan has a sizeable potential tea growing area that exists in different agro ecological zones of northern highlands of NWFP. Climate of these areas appears appropriate for certain tea varieties of shrub-type which can tolerate cold and drought conditions. Successful cultivation of Chinese tea varieties at NTRI has demonstrated the potential of large scale tea production in the region.
Konsh valley at 1500 masl and Pakkhal valley of district Mansehra at 1000 masl have the potential for tea cultivation. Pakkhal Valley, one of the largest valleys of district Mansehra near NTRI was selected for the comprehensive study to evaluate its soil status for tea cultivation with the objective to study the suitability of area for tea cultivation, to maintain desirable soil pH by the use of amendments and to study the effect of N on the yield and quality of the tea leaves. Thirty four (34) sites were surveyed and the soil samples up to the depth of 45 cm with an interval of 15 cm were collected from the smaller homogeneous units for physical and chemical studies. These studies consisted. of soil pH, texture, lime, organic matter, total nitrogen, available phosphorus and potassium. Most of the area was found suitable for tea plantation.
In the nursery the high pH soil was supplemented with different doses of farm yard manure (FYM), aluminum sulphate (Al2(SO4)3) and crude sulphur (S). Significant reduction in soil pH was observed with Al2(SO4)3 @ 600 gm-3 resulting in the production of healthy clones.
The main emphasis was laid upon the qualitative components of the fresh tea leaves as affected by different levels of nitrogen during different plucking seasons at lower (1000 masl) and higher altitudes (1500 masl). Levels of nitrogen applied were 0, 120, 180, 240, 300, 360, 420 kg ha-l to seven years old tea bushes at both the altitudes. In addition, doses of other major nutrients phosphorus (30 kg ha-1) and potassium (90 kg ha-1) were kept constant. The tea leaves were plucked during various months and used for the determination of water extract substances (WE), total polyphenols (TP), amino acid (AA), epigallocatechin (EGC), epicatechin (EC), and caffeine. In the WE, TP, AA of the tea leaves were determined by using 751 G DV -spectrophotometer and EGC, EC and caffeine contents were determined using the high performance liquid chromatography (HPLC). The highest yield of the fresh tea leaves at both the altitudes was obtained by the application of 420 kg N ha-1. The nitrogen level did not affect the quality of WE compounds significantly. However TP increased significantly at P<0.001 level during the month of July by the application of 180 kg Nha-l at 1000masl. The same dose of nitrogen gave the maximum TP during May, July, August and September at 1500masl. The EGC, EC contents increased up to certain level with the increase of nitrogen and then declined after the application of 180 kg ha-1. The nitrogen level did not affect the caffeine contents at both the altitudes.
From the study, it can be concluded that the area of Pakkhal valley has the potential for raising good crop of tea. However, the soils have average pH, higher than that is considered optimum for tea, which can be brought down with the application of aluminum sulphate or sulphur. Ammonium sulphate fertilizer can also be used for reduction of soil pH in addition to its effect on crop yield. Significant improvement in tea yield can be achieved through the application of N @ 420 kg ha-1 to the soils of the area.
During the present study it was observed that the valuable foreign exchange component (FEC) being spent on the import of tea could be saved to some extent by planting tea on commercial scale in the northern parts of NWFP. The areas having soil pH 6.5-7.0 should be amended with aluminum sulphate or sulphur to bring the soil pH to a desirable level. For maximum yield and quality tea, the desired level of nitrogen could be used to enhance the vegetative growth and characteristic components of the tea flush.