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Growth regulators are used in tea plantations from planting to productivity. Paclobutrazol at 500 ppm applied on foliage, 1 month after planting, promotes lateral production, besides feeder root proliferation. Triacontanol at 2 ppm applied in mature tea improves productivity through enhanced photosynthesis, favorable partition of assimilates, and water-use efficiency. Hydrogen cyanamide applied on the pruned frame at 0.5% improves budbreak. Antitranspirants based on long-chain polymers impart drought-tolerance in young and mature tea. Thus, use of PGR for cost-effective management of tea plantations, without affecting the quality of made tea or bush health, has been standardized.
Seed germination of four Litchi chinensis Sonn. cultivars (`Deshi', `Kasba', `Purbi', and `Early Bedana') was studied under various conditions, viz. in soil beds exposed to sunlight or in shade, in sand beds exposed to sunlight or in shade, and on moist filter paper. Among all, shaded, humid sand at 35 ± 2C gave the highest germination. Delaying sowing seeds after removal from the fruit significantly reduced germination. Litchi seeds held in polyethylene bags up to 4 days at 37 ± 2C at 90% relative humidity delayed loss of seed viability. Germination was improved by ethephon in `Deshi' and `Early Bedana', by IBA in `Deshi' and `Purbi', and by 100 mm GA3 in all litchi cultivars. Cultivars responded differently to growth regulators, with `Deshi' responding significantly better than `Purbi', `Kasba', or `Early Bedana'. These studies point to the recalcitrant nature of litchi seeds. Chemical names used: gibberellic acid (GA3); indole butyric acid (IBA); 2-chloroethylphosphonic acid (ethephon).