Molecular Frameworks of Nitrogen Response in Plants: A Review

Nitrogen is a crucial element for all living organisms especially plants which rely on substantial nitrogen quantities to sustain their growth and productivity. Crop production is greatly influenced by nitrogen consumption efficiency and a significant amount of nitrogen fertilizers is used to increase yield. Approximately half of N fertilizers are not utilized by the crops and are lost to the environment by polluting water sources or by releasing pollutants into the atmosphere. From the rhizosphere, plants absorb nitrogen in the form of nitrate (NO3-), ammonium (NH4+), or organic nitrogen (amino acids and urea). Plants exhibit an array of sensing and adaptive mechanisms to respond to the diverse nitrogen nutrition conditions which include morphological and physiological responses. Two primary systems govern nitrogen uptake in plants: the High-affinity transport system (HATS) and the Low-affinity transport system (LATS). Nitrate transporters fall into two categories, Nitrate Transporter 1 (NRT1) and Nitrate Transporter 2 (NRT2) transporters, Chloride Channel Family (CLC) transporters and Slow Anion Associated Channel Homologs (SLAC/SLAHs). The ammonium transporter family includes Ammonium Transporter 1 (AMT1) and Ammonium Transporter 2 (AMT2) transporters. The uptake of organic nitrogen is facilitated through amino acid and urea uptake and transport systems. In fluctuating environmental conditions, plants employ nitrogen response mechanisms to fine-tune homeostasis. A comprehensive understanding of these regulatory mechanisms holds the potential to yield valuable insights for the development of crops with enhanced nitrogen use efficiency.

Application of Chitin Improves Growth, Yield and Secondary Metabolite Production in Turmeric (Curcuma longa L.)

A field experiment was conducted in Trivandrum district during June 2021 to January 2022 to evaluate the effect of chitin on growth, yield and secondary metabolite production in turmeric. Soil application of chitin at 5 g per plant was done at 60 and 180 days after transplanting, while untreated plants served as control. Observations were recorded on effect of chitin on growth, defense enzymes, yield, secondary metabolites and disease incidence. Results of the study confirmed significant enhancement in growth, yield and secondary metabolite production on chitin application compared to the untreated control. Significant increase in shoot weight and rhizome weight was observed at six months after transplanting in response to chitin application. Fresh and dry rhizome yield per plant increased by 60.16% and 65.97% respectively, over the control. The defense enzyme activity and chlorophyll content were significantly higher in plants subjected to chitin application, compared to the control. Chitin treatment enhanced volatile oil and oleoresin content by 1.39 and 1.41 times and curcumin content by 21%, over the control. The results confirmed that chitin is a potent biostimulant that can be used for growth, yield and quality enhancement in turmeric.