Paramasivam Dhamodharan’s research while affiliated with Tamil Nadu Agricultural University and other places

Machine picking in cotton is an emerging practice in India, to solve the problems of labour shortages and production costs increasing. Cotton production has been declining in recent years; however, the high density planting system (HDPS) offers a viable method to enhance productivity by increasing plant populations per unit area, optimizing resource utilization, and facilitating machine picking. Cotton is an indeterminate plant that produce excessive vegetative growth in favorable soil fertility and moisture conditions, which posing challenges for efficient machine picking. To address this issue, the application of plant growth retardants (PGRs) is essential for controlling canopy architecture. PGRs reduce internode elongation, promote regulated branching, and increase plant compactness, making cotton plants better suited for machine picking. PGRs application also optimizes photosynthates distribution between vegetative and reproductive growth, resulting in higher yields and improved fibre quality. The integration of HDPS and PGRs applications results in an optimal plant architecture for improving machine picking efficiency. However, the success of this integration is determined by some factors, including cotton variety, environmental conditions, and geographical variations. These approaches not only address yield stagnation and labour shortages but also help to establish more effective and sustainable cotton farming practices, resulting in higher cotton productivity.

Background With increasing labor challenges, achieving complete mechanization in cotton cultivation has become an urgent necessity in India. For mechanized cotton cultivation, it is necessary to have appropriate variety with designed canopy architecture. The required canopy architecture with higher seed cotton yield may be attained through optimizing crop geometry and spraying of plant growth regulators like mepiquat chloride. Also, application of mepiquat chloride alters canopy architecture in cotton by creating a more compact canopy suited for mechanization. In this study, we have optimized the different crop geometries and also studied the growth and yield potential of different desi varieties viz., CO 17, VPT 2 and Suraksha with respect to plant growth regulators. This study mainly deals with growth, physiology, dry matter production and yield of each compact cultivars by application of plant growth regulators grown under diverse spatial patterns. Results Among the three varieties tested, Suraksha variety significantly recorded optimum plant height, accumulated more dry matter in fruiting bodies, produced more sympodial branches and boll numbers per plant, and higher seed cotton yield compared to CO 17 and VPT 2 varieties. Increased plant densities significantly increased the dry matter production because of higher plant population per unit area. However, wider spacing of 90 cm significantly recorded greater plant height, more sympodial branches and boll numbers per plant, and seed cotton yield compared to narrow spacing of 70 cm. The combined application of mepiquat chloride with cyclanilide @ 400 ppm at square initiation and boll development stages had significantly increased the sympodial branches and number of bolls per plant, accumulated more biomass content in fruiting bodies and increased seed cotton yield, whereas application of mepiquat chloride alone accumulated more biomass content in vegetative parts and recorded greater plant height, and internodal distance. Conclusion Suraksha variety sown under spacing 90 x 15 cm and treated with mepiquat chloride with cyclanilide @ 400 ppm at square initiation and boll development stages resulted in higher number of bolls per plant, boll weight and seed cotton yield under mechanized cultivation. This combination also produced a desired plant architecture suitable for mechanical harvesting.