Diagnosis of thermal and nutrient stresses in wheat (Triticum aestivum L.) using remote sensing techniques and their management

Field investigations focusing on “Diagnosis of thermal and nutrient stresses in wheat (Triticum aestivum L.) using remote sensing techniques and their management” were carried out during Rabi seasons of 2013-14 and 2014-15 at Research Farm, School of Climate Change and Agricultural Meteorology, Punjab Agricultural University, Ludhiana (Long 75.48‟E, Latitude 30.56‟N and 247 abmsl). The experiment was laid out in Splitsplit plot design with three replications having three temperature regime (D1= October 30, D2= November 15 and D3= November 30) in main plot, three nitrogen level (N1=RDF (Recommended dose of N), N2=125% RDF (25% more than recommended N), N3=150% RDF (50% more than recommended N) in sub plot and four postanthesis strategies (P0=Control, P1= Water sprayed, P2= Foliar spray of ZnSO4.7H20 (0.5%), P3= Thiourea (10 mM) at anthesis and 20 days after anthesis in sub-sub plot during both years. The crop sown on October 30 having 150% RDF and foliar spray with ZnSO4.7H2O (0.5%) at and 20 days interval after anthesis experienced low canopy temperature. The PAR interception and relative humidity was higher in October 30 sowing as compared to November 15 and November 30 sowing. The vegetation indices (NDVI, GNDVI, DVI, RVI and GI) computed from spectral reflectance data with the increased in crop biomass, attained a maximum value at anthesis (90 DAS) and thereafter decreased. All the vegetation indices values were improved by spraying the crop with ZnSO4.7H2O (0.5%) followed by Thiourea (10 mM) and water over control although differences recorded were non significant. The significantly higher values of these indices were recorded in Oct 30 sowing with 150% RDF as compared to other treatments. The periodic plant height, LAI, dry matter production, tiller production were significantly higher in October 30 sowing with 150% RDF. The significantly higher biological, straw and grain yield were recorded under crop sown on October 30 as compared to November 15 and November 30 although biological, straw and grain yield of October 30 sowing was statistically at par in November 15 sowing. The delayed sowing resulted in the increase in N, P and K content in November 30 as compared to November 15 and October 30 sowing but uptake of N, P and K was more in October 30 sowing because of longer duration of crop. The N, P and K content and uptake increased in 150% RDF than other nitrogen levels. The foliar spray of ZnSO4.7H2O (0.5%), Thiourea (10 mM) also improved the N, P and K content as well as uptake than control plots. The quality parameters (protein content, grain hardness and appearance) were significantly better in October 30 sowing with 150% RDF. The quality parameters (protein content, grain appearance and hardness) were significantly improved in October 30 with 150% RDF and foliar application of ZnSO4.7H2O (0.5%). The productive environmental variables (GDD, SDD and HUE) were combined with vegetation indices (NDVI, DVI, GNDVI, RVI, GI) and biological variable (LAI, Dry matter production) and reflected the overall good correlation with yield and dry matter, showing their potential use for crop weather models and yield forecasting.