Climate shift threatens Nilgiris tea plantations, says UPASI official

UDHAGAMANDALAM: Rising temperature and erratic weather patterns driven by global climate change and Super El Nino conditions are posing an unprecedented challenge to the tea plantations in the Nilgiris district, an official said on Monday (July 27).

Since tea is harvested continuously as young shoots, even small changes in climate directly affects shoot growth, internodal length, harvesting time, yield, and long-term bush health besides quality, he said.

Anthropogenic climate change has intensified these constraints across plantation agro-ecosystems due to the rising mean temperature, irregular rainfall distribution, prolonged dry spells, frost, hailstorms, high-intensity rainfall events and shifting pest/disease phenology.

"South Indian tea tracts, particularly the Nilgiris region is not governed by the quantum of total annual rainfall but by its temporal distribution: even where annual total rainfall is sustained, an increase in dry-day frequency and a rise in short-duration high-intensity rainfall events could lead to agronomically significant moisture deficits," according to a report by P Murugesan, Advisory Officer at the UPASI Tea Research Foundation Regional Centre in Coonoor.

Tea (Camellia sinensis) is exceptionally vulnerable to even slight environmental shifts. Crucial parameters such as temperature, soil moisture, irradiance, and humidity dictate the crop’s growth and overall leaf quality. While long-term meteorological data indicate that total annual rainfall volume in the region has not plummeted dramatically, the temporal distribution of rainfall has undergone a major shift, Murugesan said in his paper on "Super El Niño: Mitigation and Adaptation Strategies for The Nilgiris."

The region is experiencing a higher frequency of dry days, short-duration, high-intensity rainfall events, average temperature increase of approximately 0.5 degree celsuis, and expanded geographic reach of frost and hailstorm damage, he said, quoting long-term observatory data from the Nilgiris.

"Because tea shoots are harvested continuously, these volatile conditions directly affect internodal length, shoot development, and harvesting schedules, ultimately threatening long-term bush health and crop yields," Murugesan said, calling for urgent adaptation as the threat of Super El Nino looms.

Some of the key adaptation strategies to safeguard the region's agricultural economy against Super El Niño shocks, he recommended are immediate field-level interventions including strategic shade management, optimising canopy cover using shade trees such as Gliricidia sepium to regulate microclimates and protect tea bushes, soil and water conservation engineering and physiological safeguards, implementing customised crop care techniques to build drought resistance and prevent physiological distress in bushes.

Local estate managers and smallholders are urged to adopt these practices early to bolster resilience against impending climate extremes.

The Nilgiris plateau supports tea cultivation between approximately 1,125 m and 2,400 m elevation, with 70 per cent of tea area concentrated between 1,500–2,000 m (8 per cent at 1,000–1,500 m; 22 per cent above 2,000 m). Annual rainfall across the district is marginal (900–1,500 mm). Ooty and Kundah are predominantly south-west-monsoon-influenced, whereas Coonoor, Kullakamby and Kotagiri receive primarily north-east monsoon rainfall. Two characteristic dry spells occur: January–early April, and July–August, he said.

Diversifying planting material, avoiding large-scale monoclonal planting, scheduling pruning with reference to wind, frost and drought vulnerability, strengthening surveillance for red spider mite, blister blight and grey blight, protecting young tea via hardened nursery stock, shade, mulch and irrigation, and conservation of cultivar and shade-tree biodiversity are among the other recommendations.

"The governing principle for tea management under Super El Niño conditions is unambiguous. So, protect the bush before protecting the crop. Short-term crop extraction under severe climatic stress compromises bush vigour and future productivity. Resilient tea management therefore requires the integration of science-based early warning, field-specific adaptation, disciplined cultural practice and sustained ecological investment," Murugesan stressed.