Silicon and Nitrogen Influence on Lodging Resistance and Productivity of Rice (Oryza sativa L.)

Nitrogenous fertilizers may cause lodging which is one of the most serious problems facing rice cultivation worldwide. Lodging could be minimized by increasing the mechanical or physical strength of the rice culm, and silicon (Si) is the element associated with sturdiness and rigidity. Therefore, a field experiment was carried out in two phases with the objective to evaluate the synergistic effect of silicon and nitrogen application on lodging parameters and productivity of rice. At first phase a survey was conducted across the rice ecosystems of Telangana, and revealed that rice grown soils were low in available Si (73.62 to 96.41 kg SiO2 ha-1), whereas the rice genotypes ranged from 1.54 to 3.15% of its Si concentration and overall rice grain yield ranged from 3157 kg ha-1 to 6709 kg ha-1. Further, observed a positive and significant correlation (r=0.55**) between the rice yields (kg ha-1) and the Si concentration (%). Based on initial phase of results, a field experiment was conducted with each four levels of N (0, 80, 120 & 160 kg ha-1) and Si (0, 200, 400 & 600 kg ha-1) along with two genotypes having high Si content (3.20%) i.e., JGL-3855 and another with low Si (2.15%) i.e., RNR-2354. Conjunctive application of N and Si to both genotypes, JGL-3855 recorded significantly higher grain and straw yields compared to RNR-2354. Among the different combinations of Si and N, application of 160 kg N + 600 kg Si ha-1 recorded significantly higher grain and straw yields (7180 and 9693 kg ha-1) and on par with other treatments which received N @ 120 and 160 kg ha-1 along with Si @ 200, 400 and 600 kg ha-1. The lodging resistance parameters i.e., plant height (cm), stem length (cm), number of nodes and internodal length (cm), stem diameter (mm), linear density of culm (mg dwt cm-1) and physical strength of the culm at ripening stage of the crop influenced by different N and Si levels, but not by the varieties. Even the interaction effects of the genotypes and combination of N and Si levels did not significantly influence the lodging resistance parameters.