Evaluation of Yield, Yield Components and Growth Indices of Cotton (Gossypium hirsutum L.) and Maize (Zea mays L.) Affected on Replacement Intercropping System under Gonabad Climate Conditions

Intercropping is highly recommended to be used in many parts of the world for food or fibers productions, because of its overall high productivity. Intercropping consists of growing two or more crops together at once, even though the crops are not sown or harvested simultaneously. The success of intercropping is due to an enhanced temporal and spatial complementarity of resource capture. Many studies have reported that intercropping can increase crop yield due to efficient utilization of nutrients and light, and enhanced positive interactions between crops. Features of an intercropping system can differ with soil conditions, climate, economic situation, and preferences of the local community. In this study, we carried out a two-year field experiments to evaluate yield and yield components as well as growth indices in cotton and maize grown in an alternative intercropping systems.

The experiment was carried out based on a randomized complete block design at Gonabad Agricultural and Natural Resources Research Station. The cotton (Khordad cv.) and maize (D.C 370) plants were evaluated using an alternative intercropping system. The treatments consisted of one row of cotton along with one row of maize, two rows of cotton along with one row of maize, three rows of cotton along with one row of corn, and pure cotton and maize cropping. The seeds were sown 20 cm apart in the rows in May. Irrigation was performed every 10 days and monitored using a volumetric flow meter. Twenty days after emergence, sampling was carried out by harvesting three plants of each species to measure growth indices such as plant height, leaf rea index and dry weight. At the end of growing season the crops were harvested and yield and yield components were determined. The data were analyzed by using SAS 9.1 software.

The effect of intercropping was significant on maize seed and forage yield. Since plant density in intercropping treatments was less than pure culture, the maximum maize seed and forage yields were obtained from pure culture treatment. By contrast, the minimum seed and forage yields were related to one row maize along with two rows cotton treatment. Reduction in maize biological yield due to intercropping was reported by Khorami-Vafa (2006), Tuna and Orak (2007) and Patel et al., (1999). Three rows cotton along with one row maize treatment produced the maximum maize seed and forage yields. Yield increasing in this treatment may be due to more space between maize plants, providing more light and reducing intraspecific competition. No significant difference was found between intercropping treatments in terms of cotton yield. The maximum cotton yield was obtained from cotton pure cropping, whereas, the minimum yield was related to one row cotton along with one row maize treatment. Amongst intercropping treatments, the maximum cotton yield was obtained from two rows cotton along with one row maize treatment. The increase in maize and cotton biomass followed a similar trend in both years. The maximum reproductive and vegetative branches, dry matter and leaf area index were related to two rows cotton along with one row maize treatment. The maximum maize leaf area was related to three rows cotton along with one row maize treatment. In general, dry matter accumulation linearly increased 30 days after seed sowing in both maize and cotton plants and reached to its maximum 60 days after seed sowing and then started to decrease due to leaf senescence and abscission. Furthermore, in both species, leaf area index reached to its maximum 69 days after seed sowing and then started to decrease due to canopy closure, shading, leaf senescence and abscission. Mukhala et al, (1999) and Koocheki et al, (2010) have shown intercropping cause a significant increase in leaf area index.

Generally it is concluded that maize and cotton yield in intercropping treatments were higher also traits such as leaf area index and dry matter accumulation in one row maize along with three row cotton was higher than other treatments.