Title : Role of exogenous application of plant metabolites in frost mitigation of mulberry under temperate climatic conditions
Abstract:
Silkworm (Bombyx mori L.) is monophagous insect and feeds exclusively on mulberry foliage. The availability of quality mulberry leaf in abundance is a prerequisite for increased sericulture practice by stakeholders. However owing to sub zero temperature during winter under temperate climatic conditions like Kashmir valley, mulberry plantation particularly the young saplings suffer frost which not only limit their growth but also results in prolonged and poor quality leaf development. Different long and short term strategies have been adopted to address the issue of frost in mulberry including creation of barricades around juvenile plantation, use of smoke etc and use of different types of chemicals as well. However in the present study the mulberry saplings grown under polyhouse were treated with chemicals including melatonin and proline. Both the chemicals were used at three different concentrations melatonin (C1: 250µM; C2: 500 µM & C3: 750 µM) and proline (C1: 10 mM; C2:20 mM & C3: 30 mM) respectively. The saplings were put for the cold shock treatments for two durations viz, D1 (24 hrs) & D2 (48 hrs). Among the chemical treatments evaluated, melatonin (Ch1) was found to be more effective than proline (Ch2), particularly at concentrations C2 and C3, in reducing frost damage in mulberry saplings. Chemically pre-treated saplings showed approximately 60% mitigation in frost injury, indicating enhanced cold tolerance, which offer practical benefits to farmers facing climatic uncertainties. The application of these treatments, especially at concentration C2 (500 µM for melatonin and 20 mM for proline), significantly reduced stress-related biochemical markers. Electrolyte leakage decreased to (22.02%), while malondialdehyde (MDA) content and reactive oxygen species (ROS) activity were lowered to (2.81 µM/g and 3.38 µM/g), respectively.
