The Effect of Cytokinin and Auxin Hormones on the Distribution and Accumulation of Chlorine and Some Macroelements in Different Sectors of Maize in Different Planting Patterns in Saline Condition

Maize (Zea mays L.) which belongs to the Poaceae family is the third important cereal crop of the world after wheat and rice. Salinity is one of the major environmental factors limiting plant growth and productivity. Maize is sensitive to salinity. Planting method is a crucial factor for improving crop yield. Planting methods in saline and non-saline conditions are different. Kinetin is one of the cytokinins known to significantly improve the growth of crop plants grown under salinity. Indole acetic acid (IAA) is also known to play a significant role in plant tolerance to salt stress. However, little information appears to be available on the relationship between salinity tolerance and auxin or cytokinin levels in plants. In this respect, the objective of this study was to study the effects of foliar application of cytokinin and auxin hormones on distribution and accumulation of chlorine and some macro elements in different parts of maize in salinity conditions.
The experiment was carried out at Bushehr Agricultural and Natural Resources Research and Education Center, Dashtestan station with 29° 16´ E latitude and 51° 31´ N, longitude and 70 m above the see surface during the 2014 growing season. Dashtestan region is a warm-arid region with 250 mm precipitation per year. The field plowed inApril 2014 and then prepared and sowed inAugust 2014. There were five rows with 75 cm distance. The experiment was conducted as a split-plot design based on complete randomized blocks with three replications. Planting pattern (ridge planting, double rows of planting on a ridge in zigzag form and furrow planting) as the main factor and use of hormone (not consumption (control), application of cytokinin hormone in the time of V8-V10 and application of auxin hormone at the silking stage) was considered as the sub-factor. Cytokinin (Benzyl Adenine, Merck) and Auxin (Indole-3-Butiric Acid, Merck) were sprayed on the entire plant in the evening with concentration of 50 and 10 g. l-1, respectively. All traits measured on 10 randomly selected plants of each plot. Data analyzed using the SAS (Ver.9.1) and comparing of the means was conducted using Duncan’s multiple range test.
The measured salinity of soil at a depth of 0 to 30 cm in different locations of planting patterns and in different time period showed that in different planting patterns because salt movement by capillary ascent and its accumulation in the ridges, salinity center stack was the highest and the lowest salinity belonged to the furrow planting. The highest Potassium (K) and Calcium (Ca2) ions were obtained with pattern of furrow planting, while the highest sodium ions (Na), Chlorine ions (Cl-) and Naﲯ were devoted to the pattern of conventional planting (ridge planting). Foliar application of benzyladenine (BA) and indole-3-butyric acid (IBA) sodium ions (Na) and Naﲯ. The results showed that in all three planting pattern the most sodium leaf was obtained without the use of hormone auxin, but the lowest amount of sodium leaf was observed with auxin treatment. In each pattern, use of hormone leading to increased potassium of shoot, but the largest increase was cytokinin hormone, of course, the greatest increase was achieved by application of cytokinin hormone. In furrow planting use of hormone reduced the amount of leaf chlorine so that most leaf chlorine was obtained without the use of hormones. While, use of cytokinin and auxin hormones reduced the amount of leaf chlorine by 6.86 and 21.24 percent, respectively. Use of hormone in all planting methods reduced the amount of shoot chlorine but the greatest reduction was achieved by application of cytokinin hormone.
In general, it can be concluded that increasing concentrations of sodium, magnesium and chlorine in leaves and shoots in row planting compared to planting two rows and furrow planting could be related to higher concentrations of these elements in the soil and in the location of the plant and as a result decrease of plant growth and therefore higher concentration of elements in various parts of the plant in the row planting. It is concluded that use of cytokinin and auxin especially in the furrow planting reduced the concentration of sodium, chloride and sodium to potassium ratio and increased plant potassium and calcium concentration.