Impact of growth retardants on sporadic irrigation during the water shortage stress phase in the Nagpur mandarin (Citrus) Mrig (Monsoon blooming) crop

Abstract

In 2015, a field study was conducted in the Nagpur mandarin (Citrus reticulata Blanco) experimental orchard at CCRI, Nagpur in block number 44. In addition to replacing the import of fresh fruits, breaking the seasonality of Nagpur mandarin for commercial production will provide Nagpur mandarin producers incentive pricing. Common methods used to control blooming include root cutting, root exposure, and water withholding. Growth retardants like paclobutrazol and chlormequat chloride have been successfully employed in recent years to cause early blooming for off-season output in a number of fruit crops. Withholding water for around 30 to 45 days before to anticipated blooming exposes citrus plants to water shortage stress. Climate change-related untimely showers often cause this tension to be broken, leading to poor or nonexistent blossoming as a consequence of the absence of flowering stimulation. Thus, these tests were carried out to evaluate the efficacy of two plant growth regulators, paclobutrazol and chlormequat chloride. During the stressful second week of May, flood irrigation was administered, and the treatments that followed were used to reimpose the stress that intermittent watering had broken. Nagpur mandarin trees that were six years old used as experimental plants. The trees were taught to have a single stem and were all the same size and age. During the research period, the trees were cultivated using drip irrigation in accordance with customary cultural practices. Seven treatments were reproduced four times in a randomised block design. For every replication, four trees were employed. Four months before to blooming (June), the medicines were administered. Chlormequat chloride 2000, 3000, and 4000 ppm as a foliar spray, paclobutrazol 6 g, 9 g, and 12 g as a soil application, and a control were the treatments tested. Weekly observations were made of the temperature, humidity, and rainfall in the orchard microclimate, as well as the soil moisture content (%) and leaf water potential (ΨL). Up until mid-June, Paclobutrazol 12g demonstrated the highest water stress in terms of leaf water potential (ΨL), which varied from -3.00 MPa to -3.17 MPa. During June and July, there was no blooming because to the high temperature (41.28°C), limited rainfall (6 mm), and low humidity (40.71%). Using sprinklers and irrigation to regulate the orchard's microclimate may assist maximise the blooming potential reached via growth.