جستجوی مقالات مرتبط با کلیدواژه « جرم مخصوص ظاهری » در نشریات گروه « باغبانی »

Soil salinity and compaction are probably the most prevailed limitations for crop growth and production. Their mitigation and control may be important crop management keys that can ensure yield sustainability and optimum use of land and water. This research was performed to investigate the combined effect of soil salinity and soil compaction on some growth characteristics of corn (Zea mays L.) root. For this purpose, a factorial pot experiment on the basis of completely randomized blocks design with three replications was performed. The experimental factors were three levels of soil salinity (electrical conductivity of saturated paste extract of 1.5, 2.5 and 4.5 dS/m) and three levels of soil compaction (bulk density of 1.3, 1.55 and 1.75 g/cm3). For salinity treatments, different amounts of NaCl was dissolved in the required volume of distilled water to have soil water content to 16% and then were added to the soil. For soil compaction treatments, a 4.5 kg solid cylinder was allowed to fall freely from 45 cm height over the soil surface in the pots. During the 3 months of experimental period, the pots were irrigated with distilled water through regular weighing. Results showed that the main effects of soil salinity and compaction at 1% probability level and their combined effects at 5% probability level led to significant reduction in root dry weight, root volume, root length, root mean diameter and ratio of root weight to soil weight. Combined effects of soil salinity and compaction reduced growth characteristics of the corn roots 20% more than their individual effect. Therefore, it can be concluded that soil salinity and compaction intensify their negative effects and suppress growth and development of corn roots.

In order to determine the effects of different tillage methods on apparent density of soil and yield of forage corn¡ experiments were carried out on a land in Miandoab town from west Azarbaijan. The treatments include: moldboard plow and double disk¡ chisel plow and double disk¡ disk plow and double disk and cultivator with one disk. The results showed that different tillage methods have significant effects on apparent density during different measurement period (1 day¡ 15 days¡ and 30 days after tillage). Maximum apparent density related to cultivator treatment during 30 days after tillage with 2.18 g/cm3 and minimum apparent density related to disk plow treatment during one day with 1.69 g/cm3. By increasing time of measurement after tillage¡ the ration of apparent density increased 23%. In deeps of (0-5)¡ (5-10) and (10-15) cm of soil¡ variation of apparent density of soil was not significant. Effects of tillage methods on yield of forage corn by one percent probability were significant and maximum performance related to disk plow with 61.5 tons per hectare.