Effect of cytokinin and auxin hormones on yield and dry matter remobilization of corn in different planting patterns under saline conditions

Introduction Maize (Zea mays L.) belongs to the family Poaceae and it is the first important cereal crop of the World (FAO, 2013). Salinity is one of the major environmental factors limiting plant growth and productivity. Maize is sensitive to salinity (Turan et al., 2009). Planting method is one of a crucial factor for improving crop yield. Planting methods in saline and non-saline conditions are different. Cytokinin (Rajala and Peltonen-saninio, 2001) and Auxin (Jung and Park, 2011) are known to play a significant role in plant tolerance to salt stress and to significantly improve the growth of crop plants grown under salinity. However, little information appears to be available on the relationship between salinity tolerance and auxin or cytokinins levels in plants. In this respect, the objective of this study was to study the effects of foliar applications of cytokinin and auxin hormones on yield and dry matter remobilization of grain Maize (Zea mays L.) under different planting patterns in saline conditions. Materials and methods The experiment carried out at Bushehr Agricultural and Natural Resources Research Center, Dashtestan station with 29° 16´ E latitude and 51° 31´ N longitude and 70 m above see surface during 2013 growing season. The field plowed by April at 2013 and then prepared and sowed by August at 2013. There were five rows with 75 cm distance. A split factorial design based on complete randomized blocks with three replications was conducted. Planting pattern (ridge planting, double rows of planting on ridge in zigzag form and furrow planting) as the main factor and time of cytokinin (0 as control, V5- V6 stage and V8- V10 stage) and auxin (0 as control, silking stage, two weeks after silking stage) foliar-applied was considered in a factorial. 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 morphological and yield component traits measured on 10 randomly selected plants of each plot. Yield was measured in 9 m2 for each treatment. Data analyzed using the SAS (Ver.9.1) and Significance of differences between means was conducted using Duncan’s multiple range test. Results The results showed that different planting patterns in terms of amount, efficiency and contribution of dry matter remobilization (DMT), amount, efficiency and contribution of current photosynthesis (CP), 1000 kernel weight, grain yield and harvest index were significant. Generally, results of this research indicate improved yield and yield components of maize due to the change pattern from one row to the furrow planting in salinity conditions. At the times of BA application, the maximum amount of amount and contribution of DMT Was dedicated to non-use. While the maximum amount of efficiency and contribution of CP Was dedicated to time consumed V8- V10 stage. The maximum amount of amount and contribution of DMT, amount of CP, 1000 kernel weight, grain yield and harvest index produced by time of auxin foliar-applied in silking stage and the most CP and biological yield was assigned to the non-use. It has been found that both auxin and cytokinin may have a role in mediating cell division in the endosperm during the grain-filling stage. Therefore, these hormones might regulate the grain capacity (sink size) for the accumulation of carbohydrates (Koocheki and Sarmadnia, 2012). It has been found that IAA actively participated in the mobilization and accumulation of carbohydrates in seeds (Darussalam Cole and Patrick, 1998). Auxin and cytokinins hormones are also thought to be involved in regulating sink strength either by mediating the division and enlargement of endosperm cells or by controlling the import of assimilates to the sink (Kaya et al., 2010). Conclusions It is concluded that furrow planting with CK application in V8- V10 stage (50 g. l-1) and IBA in silking stage (10 g. l-1) reduced effects of salinity on plant and produced the highest grain yield. Due to its effect on diminishing salt aggregation in relation to ridge planting, furrow planting prepare semi saline and saline areas for growing crops.