Marginal conditions occur when one or more of these ideal growing conditions is not met and where major corrective action needs to be taken to obtain a commercial yield. The symptoms of marginal conditions, however, vary from the obvious to the hidden, and the effects from debilitating to death. In the last 100 years of science based tea growing we have learned many techniques for minimizing the effects of less than ideal conditions – irrigation, shading, fertilizer, land drainage, soil acidification, all spring to mind – but be aware that though effective such techniques increase the cost of production, so have to be factored into your business plan.
Some examples and typical remedies for common marginal conditions are illustrated below under the heading Genetic Options.
a) Adapted plants. Good tea is better grown under marginal conditions by using the clones or jats that have been bred locally to withstand them. Thus clones offered by most Tea Research Institutes are selected to resist local problems of drought, high pH, diseases, and insect damage. In cold areas the var. assamica type gives way to the var. sinensis but, due to the locations of the most active TRI’s, the majority of tea breeding has been directed at the assamica derived material. When we started the Pakistan project we sought out genetic material from around the world for Lever Brothers that would resist frost while yielding high and having good cup quality. After selection work in plot trials they doubled the yield of imported seedling tea from Turkey, which has a similar marginal climate to Pakistan. Collection of diverse Camellia tea genetic material will be undertaken for the US League of Tea Growers by MSU and an accessions collection built up at Crystal Springs, MS. From this collection will come new varieties and clones to fully meet a wide range of US growing conditions.
b) Natural Selection. One of the few advantages of growing tea under marginal conditions is to utilize the natural selection pressures that these conditions apply. In many countries selections have been made from imported tea plantings that had been abandoned – in Pakistan up to 30 years previously and in South Carolina in 1965-85 by TJ Lipton using material abandoned by Charles Shepard in 1900. The survivors, though often barely growing, come through extreme marginal conditions combining poor drainage, high pH, drought, and low nutrients. Selections from these survivors, under normal husbandry conditions in Pakistan proved to be extremely vigorous and high yielding. Reliable and precise small scale processing of leaf, even from a single bush, is possible using the Teacraft ECM Miniature Manufacture System – “the tea factory in a packing crate”. Selections can be assessed at a very early stage and duds abandoned. This approach fast tracked selection of good commercial clones combining yield and cup quality that were well suited to local conditions.
Planning for bad conditions:
So, how well will tea grow on your farm or in your back yard? When new tea areas are being planned, or when doubts are being expressed about the commercial potential of poorly growing areas, there is a need to assess and quantify how marginal the conditions are, and then to calculate the cost of adjusting them. Unless records are already available this requires conditions to be monitored and recorded over time, and it needs comprehensive expertise and advice to effectively adjust techniques to the prevailing conditions. Thereafter is a need to actually test crop responses to the altered conditions. Full assessment requires:
- Weather Records – preferably from data logged automatic weather stations
- Soil analyses – physical and chemical.
- Selection of suitable plant material
- Test sites for yield and quality trials
- Foliar analysis to monitor on-going plant responses
- Cup quality evaluation – early indications from single bushes and plot trials – the Teacraft ECM miniature factory – as used around the world, to check potential tea quality before making capital investments
This assessment is specialist work and relates more to would be tea farmers rather than the back yard novice. But as was suggested at the beginning – it takes some expertise to grow tea well under marginal conditions. With one or two tea bushes a mistake will not be so costly but with a few acres of bushes the cost can be significant. When planning new tea growing in a new area, the use of suitably qualified technical advice can make the difference between commercial success and failure.