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11.
Ali Asghar Zolfaghari Ruhollah Taghizadeh-Mehrjardi Farrokh Asadzadeh Mohammad-Ali Hajabbasi 《Archives of Agronomy and Soil Science》2016,62(2):163-175
In this study, the effect of land-use treatments and the feasibility of fractal dimension to quantify soil aggregate stability were investigated in the central Zagrous, Iran. For this purpose, the non-linear fractal dimension (Dnl), linear fractal dimension (Dl) and the mean weight diameter (MWD) of aggregates were compared. Soil samples from three sites with four adjacent land-use types, namely: forest area (F), cultivated lands adjacent to forest (CAF), pasture (P) and cultivated lands adjacent to pasture (CAP) were collected. Results showed that soils under cultivated lands had higher bulk density (BD) (1.30–1.38 Mg m?3) compared to the adjacent soils under forest (1.19 Mg m?3) and pasture (1.21 Mg m?3). In the 0–15 cm layer, soil organic matter (SOM) content in the cultivated plots were respectively 30% and 31% lower compared to the forest and pasture soils. The lowest CVs belonged to Dnl (5–8%) demonstrating that Dnl was more accurate than Dl (8–14%) and MWD (30–53%) methods. CAP had the largest value of Dnl, while P had the smallest value of Dnl. Difference of Dnl between forest and pasture was not significant, whereas both of them significantly differed from CAF and CAP. Dl did not differ significantly between forest and CAF. There were significant differences between forest and pasture for the measured MWD. Both fractal dimensions had negative correlation with MWD, SOM, hydraulic conductivity (HC) and macroaggregates (>0.25 mm) and positive correlation with BD and total porosity (TP). 相似文献
12.
Drought tolerance is one of the most important objectives of sugar beet breeding programs in semi-arid regions, particularly
during the last decade. Due to global climate changes and limitations of agricultural irrigation water, varieties with drought
tolerance are taken into consideration in order to avoid yield losses due to drought. In this study, drought tolerance of
76 S1 lines (full-sib families) that had been extracted from a genetically broad base multigerm sugar beet open pollinated population,
were examined. Test crosses were made between the lines as pollinators and a cytoplasmic male sterile (CMS) single cross.
The consequent hybrids along with checks were evaluated during 2007 and 23 more tolerant hybrids during 2008, in two adjacent
experiments under drought stress and non-stress conditions. Drought tolerance indices calculated based on sugar yield, such
as mean productivity (MP), geometric mean productivity (GMP) and stress tolerance index (STI) were used to assess hybrids
responses to drought. The results showed significant genetic differences for root yield and sugar yield under both conditions.
Drought tolerance indices displayed significant genetic variability for sugar yield among the hybrids. Many hybrids were drought
tolerant as compared with the original base population as indicated by their high STI. The estimates of heritability for sugar
yield in stress and non-stress conditions were much close to each other (0.31 and 0.34, respectively). Whereas, for root yield
the heritability estimate in stress condition (0.46) was relatively higher than that in non-stress condition (0.34). Significant
differences were observed among the selected hybrids for root yield and sugar yield, indicating genotypic variability for
pollinator lines derived from the population. There were no significant differences for sugar content. For increasing the
drought tolerance potential in a breeding population and developing drought-tolerant varieties by male parent, the drought-tolerant
lines could be used. 相似文献