RESPONSE OF NITROGEN FERTILIZATION ON BT AND NON-BT COTTON (Gossypium hirsutum) HYBRIDS
A field experiment was conducted during 2006 and 2007 (June- December) at New Delhi to assess the performance of three cotton hybrids of which two Bt (MRC 6304 & RCH 317) and one non-Bt cotton hybrid LHH 144 (North zone check) in response to nitrogen fertilization (0, 60, 120 and 180 kg ha -1 ). Based on pooled analysis, both Bt hybrids produced similar seed cotton yield (SCY). Bt hybrid have produced 7.1 bolls/plant (on an average) and bolls 0.48 g heavier than non Bt hybrid LHH 144 that lead to 1.07 t ha -1 higher SCY of Bt hybrids than non-Bt hybrid (1.93 t ha -1 ). Though the N uptake by cotton hybrids was statistically similar N harvest index (NHI) was higher in Bt hybrid (57.85) as compared to non-Bt hybrid (40.5). The agronomic N use efficiency (ANUE) was highest in MRC 6304 Bt (6.44) and least in LHH 144 non-Bt cotton (3.91). Cotton growth, yield attributes, SCY, and N uptake increased with each successive increase to the highest level of 180 kg ha -1 however, the N response of cotton was quadratic in nature with optimum dose of 173.0 kg ha -1 . The NHI decreased with increase in N dose i.e. from the highest of 56.3 in control to the lowest of 48.8 with 180 kg ha -1 N fertilization. ANUE and physiological NUE that was highest with 60 (5.73) and 120 kg N fertilization (17.05), respectively and decreased with further increase in N dose. The cotton hybrid x N interaction effect revealed that Bt cottons have quadratic N response while non-Bt cotton has linear N response. From the economic point of view, Bt hybrids with 120 kg Nha -1 could be optimum dose for cotton cultivation. DOI:  http://dx.doi.org/10.3329/sja.v11i1.18389 SAARC J. Agri., 11(1): 121-132 (2013)
Productivity of BT and Non BT Cotton (Gossypium hirsutum L.) Cultivars as Influenced by Plant Geometry and Fertilizer Levels
Cotton is a natural part of everyday life which serves the mankind from the cradle to the grave. Cotton plays a key role in socioeconomic and political affairs of the world (Kairon et al., 2004). Its production, processing and trade generate revenue and sustain livelihoods in many countries. It is the world’s leading source of natural textile fiber and fifth largest oilseeds crop which covers 40% of the global textile need (APTMA, 2012) and 3.3% of edible oil (FAS, 2014), respectively. Cotton is the most important commercial and premier cash crop of India. It plays a prominent role in farming and industrial economy of the country. With the introduction of Bt cotton hybrids, there has been a significant change in the cotton cultivation scenario of India. Now, around 40 per cent area under cotton is occupied by Bt cotton hybrids. However, the average production is very low when compared to world's average. This is mainly because 70 per cent of cotton area is under rainfed condition.
Cotton Fiber Growth and Development 2. Changes in Cell Diameter and Wall Birefringence
Cotton (Gossypium hirsutum L, and G. barbadense L.) fiber perimeter is an important textile trait that directly affects quality properties, such as fiber length, strength, and micronaire. The literature is contradictory regarding whether or not fiber diameter changes during development. Changes in maximum fiber diameter, fiber length, and cell wall birefringence were measured throughout development in four cotton genotypes (G. hirsutum, cultivars MD51ne, DP50, and DP90; and G. barbadense). All genotypes exhibited significant increases in fiber diameter during the first 30 d of fiber development. The G. hirsutum genotypes all had similar final diameters; whereas, G. barbadense had a significantly smaller final diameter. The G.