Volume 15, Issue 3 (5-2013)
Abstract
A two-year field experiment was carried out in semi-arid region of southern Iran (Shiraz), during 2007-2008 and 2009-2010 growing seasons using various mixtures of an early- (cv Falat) and a middle-ripening (cv Shiraz) winter wheat cultivar to evaluate the beneficial effects of inducing temporal growth heterogeneity on reduction of intra-specific competition during post-anthesis moisture stress conditions. Treatments were composed of five combination ratios of the two cultivars (1:0; 2:1; 1:1; 1:2, 0:1), and two levels of post-anthesis moisture conditions i.e. equal to Field Capacity and 50% FC. The results showed that the equal ratio (1:1 mixed cropping of early and middle-ripening cultivars) was superior in grain yield components as well as post-anthesis water use efficiency (PWUE) among the mixture treatments. It appeared that mixed cropping of early- and middle-ripening cultivars had the potential for altering the intensified competition under deficient moisture conditions and may improve PWUE. Additional research for determining the best choices of cultivars, mixing ratios, sowing date, phenological differences, input requirements, and management practices for each regional environment are essential to achieve the maximum benefits.
Volume 22, Issue 4 (6-2020)
Abstract
The changes in Root Length Density (RLD) of rainfed fig trees due to supplemental irrigation were studied during two growing seasons in Estahban, southern Iran, with objective of finding out the optimum position, time, and amount of supplemental irrigation. Irrigation position treatments were: (1) In a micro-catchment close to tree trunks; (2) Inside the tree canopies (1-1.1 m from tree trunks); and (3) Outside the tree canopies (2.1-2.2 m from tree trunks). Irrigation time treatments included: (a) In early spring and (b) In mid-summer; and the treatments of irrigation amount were: (i) No supplemental irrigation (control), (ii) 1,000, and (iii) 2,000 L per tree. Results showed that the highest RLD in different irrigation amounts occurred at 15-45 cm depth during late winter and late spring. However, during summers, the high RLD occurred 15 cm lower at 30-60 cm depth. Irrigation water treatments of 1,000 and 2,000 L per tree increased RLD values by 11.3 and 19.3%, respectively, in late spring and 10.5% and 14.7%, respectively, in late summer, compared with the rainfed treatment. Whereas this increase generally occurred in the wetted area; supplemental irrigation out of tree canopy could develop the root horizontal extension to a greater distance. Lower temporal variation in RLD profile was obtained for depths deeper than 75 cm, which was in agreement with soil water content variations. Supplemental irrigation applied out of tree canopy with 2,000 L per tree (200 m3 ha-1) during early spring is recommended to improve root development of fig trees in drought prone rainfed areas.
