Study the effect of different methods of applying salicylic acid on quantitative, qualitative and biochemical parameters of wheat (Triticum aestivum L.) in drained and not drained lands

Introduction Wheat is the most important crop in the country. However, a significant portion of this product is grown and produced in saline lands. In Khuzestan province, when we move from north the south, the land salinity is increased due to low slope, heavy soil texture and high water deficit. So, the major areas in Ahvaz, Shadegan, Abadan, Khorramshahr, Mahshahr, Dashte Azadegan, Hoveizeh and even in parts of Shoshtar, Ramhormoz and Behbahan are confronted with this limitation. Estimates showed that at least 400,000 hectares of south of province require underground drainage. Many studies have shown that the application of growth regulators such as salicylic acid can increase plant tolerance during abiotic stresses, especially salinity stress. Therefore, this experiment aimed to investigate and compare the effects of different methods of salicylic acid hormone application on quantitative, qualitative and biochemical parameters of wheat in drained and non-drainage lands.   Materials and methods This experiment was carried out in order to evaluate the effects of different methods of applying salicylic acid on quantitative, qualitative and biochemical parameters of wheat in drained and not drained lands, based on combined analysis with randomized complete block design with three replications. The first factor was two levels of drained lands (first experiment) and not drained lands (second experiment) and the second factor was different methods of salicylic acid application, which was 1- no spraying (control), 2- soaking of seeds 3- spraying at the beginning of tillering, 4- soaking of seeds + spraying at the beginning of tillering, 5- spraying at the end of tillering, 6- soaking of seeds + spraying at the end of tillering. In this experiment, salicylic acid was used at a concentration of 1 mM. Soaking of seeds in solution was done for 6 hours and washed with distilled water and then dried. Also, spray application of salicylic acid in different growth stages, was performed by motor sprayer. Determination of grain yield from one square meter was done from each plot after removal of margins. To determine the number of spikes per square meter, the number of spikes in harvesting area was counted and averaged in each plot. To determine the number of grains per spike, 10 spikes were selected randomly from all harvested spikes and their grains were counted and their mean was considered as grains number per spike. To determine the number of spikelets per spike, 10 spikes were cut in each plot randomly and the number of spikes was counted and their mean was considered as spikelets number per spike. 1000-grain weight was calculated based on the total weight of two 500 grains samples at the harvest stage. Chlorophyll index was determined by using chlorophyll meter at grain filling stage. Different concentrations of proline, in mg/g fresh weight, were measured by Bates method and wheat protein was measured by digestion method by Kejeldal device. Results and discussion The results showed that the effect of land type on spikes number per square meter, grains number per spike, spikelets number per spike, 1000-grain weight, grain yield, chlorophyll index, proline and grain protein percentage were significant at 1% probability level. The effect of salicylic acid levels on all traits was significant at 1% probability level. The interaction of land type and salicylic acid in terms of protein percentage was significant at 5% probability level and in term of spikes number per square meter, spikelets number per spike, 1000-grain weight, chlorophyll index and proline content were significant at 1% probability level. The maximum protein percentage (14.36%) was related to the no spraying of salicylic acid (control) in non-drainage conditions  and the minimum in drained conditions (10.6%) was related to soaking of seeds + spraying at the beginning of tillering. The maximum and minimum grain yield in drained and non-drained lands by 3308 and 2017 kg.ha-1 was observed, respectively and the maximum and the minimum grain yield in different methods of salicylic acid application was in seed soaking + spraying at the beginning of tillering and without salicylic acid application by 3636 and 1759 kg.ha-1, respectively. Conclusions In general, the results showed that the effect of salicylic acid on drained lands increased the yield parameters and on not drained lands by reducing the effects of salinity stress and improving the damage caused by it could be effective in increasing of yield. However, in this condition, the lowest yield qualitative was observed.