Cotton (Gossypium hirsutum L.) is the most important fibre crop of the world with significant role in Indian agriculture, industrial development, employment generation and contribution to the national income. It is mainly grown for textile fibre, feed, fuel and edible oil. Despite a firm competition from synthetic fibres, cotton continues to enjoy a place of prime importance in the textile industry. Under optimum growing conditions as a result of maximizing inputs for cotton production, particularly nitrogen and irrigation water, plants often become excessively tall and vegetative (Nichols et al., 2003). Thus, vigorous plant growth can be very frequent in mid to late season stages of crop development. Excessive vegetative growth often occurs at the expense of reproductive growth (Kerby et al., 1987) and a large fraction of squares and small bolls on the lower sympodia may shed and result in late maturity and often a lower yielding crop (Fowler and Ray, 1977). All squares produced by the plant do not grow into bolls and not contribute to yield (Sudararaj and Thulsidas, 1993). Cotton can shed upto 70 % of all initiated fruiting structures from sympodial branches during reproductive stage of development (Peoples and Mathews, 1981) but its extent in recently released Bt hybrids is still unknown and needs immediate attention. According to Heitholt and Schmidt, (1994), whole plant boll retention i.e. total bolls per total flowers are an imperative process affecting lint yield. A dense and lavish growth causes abnormal shedding of young fruiting bodies like buds, flowers and bolls, delayed maturity, boll rot (due to shading), decreased defoliation and reduced yield (Zhao and Oosterhuis, 2000). Thus, the plant must have a balance between vegetative and reproductive growth, where there is enough vegetative growth to provide adequate carbohydrate supply for fruit development, but not excessive vegetative growth that inhibits fruit development (Kerby et al., 1997). Kaur et al., (2015) also reviewed the importance of PGR’s in order to overcome some production constrains in direct seeded rice (DSR) and reported that certain plant growth regulators (PGRs) can prove as effective measure to ensure enhanced germination, better early seedling growth, improved root length and higher yield in DSR.

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