Biochar co-applied with organic amendments increased soil-plant potassium and root biomass but not crop yield

Journal of Soils and Sediments - Biochar can improve soil nutrient retention and alleviate salinity; however, use is not widespread due to cost. Biochar is usually co-applied with a full-rate of...     

Ecophysiological status of different growth stage of understorey Acacia leiocalyx and Acacia disparrima in an Australian dry sclerophyll forest subjected to prescribed burning

Purpose

Understorey Acacia spp. plays an important role in post-fire restoration because these understorey plants are tolerant to stress conditions. We investigated how the ecophysiological status of two species of understorey, Acacia leiocalyx and Acacia disparrima, varied depending on the plant growth stage after prescribed burning.

Materials and methods

Plants were grouped in different size classes, namely seedlings, small and medium sizes, and physiological variables such as foliar gas exchange, water use efficiency and light dependency were measured at two experimental sites subjected to prescribed burning.

Results and discussion

A. leiocalyx showed higher symbiotic N₂ fixation and photosynthetic capacity compared to A. disparrima regardless of plant-size classes at both experimental sites. This could explain the greater relative growth rate of A. leiocalyx than that of A. disparrima. However, A. disparrima is more tolerant to shady conditions than A. leiocalyx.

Conclusions

This finding may be an indication of how well these two species recover after fire, although A. leiocalyx may have faster regrowth, as it is fixing more N.     

Effects of gibberellic acid and carbon disulphide on sprouting of potato minitubers

Effects of treatments with gibberellic acid (GA₃, 50 mg L⁻¹ for 2 h) or carbon disulphide (CS₂, 25 ml m⁻³ for four days) on breaking of dormancy and sprouting of potato (Solanum tuberosum L., cvs Agria and Marfona) minitubers of different weight classes (0.3, 0.7 and 1.5 g) were investigated. The dormancy period tended to decrease with an increase in the weight of minitubers, whereas the number of sprouts per minituber, their length and fresh weight and the sprout mass per unit of sprout length of the longest sprout tended to increase with an increase in minituber weight. In both cultivars, applying GA₃ or CS₂ advanced breaking of dormancy, but GA₃ was less effective in Marfona than in Agria. Advancing breaking of dormancy was associated with removal of apical dominance and therefore applying GA₃ or CS₂ also increased the number of sprouts per minituber, especially in Agria. In Agria, the dry matter content of sprouts from the CS₂ treatment was higher than in the GA₃ or control treatments, whereas in Marfona dry matter content of sprouts was highest in the GA₃ treatment. The length of sprouts, fresh weight of sprouts and the sprout mass per unit of sprout length of the longest sprout were significantly enhanced by treating minitubers with GA₃ or CS₂ compared with the untreated control minitubers, but there were strong interactions with cultivar and minituber weight. These interactions are important in practical use of dormancy breaking methods.     

Land-use change and carbon stocks: A case study, Noor County, Iran

Land-use changes and land cover strongly influence carbon stock and distribution within ecosystems. Changing the land-use from natural forest to other land-uses has been more rapid in the past few decades than at any time in Iran’s history. In this study, we investigated the effects of changing the land-use from natural forest to other land-uses on carbon stocks in northern Iran. We selected five sites for this study: (I) a natural forest, (II) an agricultural field and (III) plantations of three different species (Alnus subcordata. L, Acer velutinum.Boiss and Cupressus sempervirens). We examined the effects of land-use changes on: (I) soil carbon stock (0–50 cm depth), (II) biomass and carbon content of grassy vegetation and litter and (III) above- and below-ground biomass C in trees. Soil C stock was higher under A. velutinum and C. sempervirens whereas it was lower under A. subcordata and agricultural sites. Biomass and C content of grassy vegetation were significantly higher at A. velutinum and C. sempervirens plantations. However, litter biomass and C content were significantly higher at the natural forest site. Natural forest had the highest amount of C content in above- and below-ground biomass. Total ecosystem C stocks declined following land-use changes.     

Reproduction of juniper (Juniperus polycarpos) in Khorasan Razavi, Iran

Juniperus species （juniper） are resistant to drought and have medicinal properties. In order to investigatethe condition of juniper reproduction and prevent a decline in its area, largely caused by problems in natural regeneration, the asexual reproduction of juniper has received special attention besides its sexual propagation. Among the six species of juniper in Iran, the most abundant are Juniperus polycarpos and J. excelsa. Juniperus polycarpos is ambi-sexual and J. excelsa unisexual. We show that collecting seeds in September provided for better germination than in November. In sexual propagation 82.0% and in asexual （graft） 47.6% success were achieved. Compared to a mixture of water, lime and hormones, a natural treatment of only water had better results. Diurnal change of temperature increased germination of juniper seeds over a constant temperature. Aphyllous stem cuttings from mature and old trees are less successful in rooting than leafy cuttings of juniper saplings. A treatment with Aaterra significantly reduced the percentage of rooted cuttings and total root length. Aliette, Fongarid, Octave, Benomyl, Delsene M and Maneb fungicides significantly increased the percentage of rooted cuttings but did not affect total root length. Autumn explants formed more calli than spring explants. Successful multiplication was achieved by treating buds with a mixture of 0.7% polyvinyl pyrrolidone （PVP） and 2% sucrose and cultured in a basal MS or WRC medium, with a maximum number of new buds. In consideration of extracted material of juniper species in remedy of infectious, fungus, contagious diseases as well as for drought resistance and longevity of this species in severe arid environmental conditions and various industrial applications, reproduction and seed production by micro propagation and biotechnology are necessary.     

丰一、薪杭等蚕品种复壮后其杂交种比较试验

对夏秋蚕品种薪杭,白云,丰一,五四等进行充血复壮改良后,其复壮系的杂交一代与现行生产系杂交一代生产性能比较试验结果表明：复壮后的2对杂交种与原来的杂交种比较,在龄期发育经过、虫蛹率等性状基本持平,产量和茧丝质方面的各项性状基本相近或有所提高。     

Endocrine disrupting effects of 4-nonylphenol on plasma vitellogenin,reproductive system and histology in koi carp (Cyprinus carpio)

International Aquatic Research - This study aimed to assess the effect of 4-nonylphenol (4-NP), a ubiquitous aquatic micro-chemical pollutant substance on some on some reproductive parameters and...     

Cardinal temperatures for seed germination of wild barley,barley grass and hoary cress

It is necessary to understand the effects of environmental conditions, especially temperature, on weed seed germination patterns, in order to make comprehensive and effective weed management decisions. The effect of cardinal temperature (0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C and 40°C) on the germination pattern of three noxious weeds, such as wild barley (Hordeum spontaneum Koch.), barley grass (H. murinum L.) and hoary cress (Cardaria draba L.) in wheat fields of Iran, was studied in three separate experiments. The experiments were conducted based on completely randomized design (CRD) with four replications. The result showed that the germination of all three species started at low temperatures and there was no significant difference in germination percentage (GP) at lower temperatures. About 50% of the weed population germinated within a short period when using a dent-like model indicating the high ability of these weeds to compete for space and resources. Segmented and dent-like models were used to evaluate the cardinal temperatures. The results showed that dent-like model was the preferred model to evaluate germination rate in relation to variable temperatures in hoary cress, while the segmented model was better in wild barley. However, there was no significant difference between the two models for barley grass. The results of this study showed that mechanical, cultural (pre-planting irrigation) and chemical practices could be more useful and effective at 10–30°C.     

Termite effects on soils and plants are generally consistent along a gradient in livestock grazing

Livestock grazing is a major driver of ecosystem functions in drylands and would be expected to influence soil biota such as termites. We examined changes in soil chemistry and plant community composition on mounds constructed by the subterranean termite Anacanthotermes ahngerianus along a gradient in grazing intensity in an arid steppe in north-eastern Iran. The grazing gradient was represented by increasing distance from an area used by resting livestock, and plant and soil attributes measured within three adjacent microsites (termite mounds, non-mound controls, intervening annular zone surrounding the mounds). Values of soil EC; pH; exchangeable Ca, Mg, and Na; and total nitrogen and organic carbon were greatest in mound soils and declined from mounds to control microsites. Mounds were completely devoid of plants. Annular zones had three-times less cover than the control sites, but there were no differences in diversity or evenness. Electrical conductivity values were ten-times greater on mounds than controls close to resting sites, but the difference diminished rapidly with distance from resting sites. For all other soil and plant variables, differences between microsites were consistent across the grazing gradient. Increased grazing intensity was associated with increasing soil pH, EC and sand content, and reduced plant cover. Overall our study shows that the effects of termites on soil chemistry and plant cover varied little across the grazing gradient. Our results suggest that termite mounds may sustain their role as sites of enhanced soil nutrients under even high levels of grazing.     

Sampling Strategies and Soil Characteristics for Estimation of Plant Patches Dimensions (Case Study: Inchebroun Rangelands,Golestan Province,Iran)

Survey and monitoring rangelands projects is one the important plans in rangelands management. For this purpose, the survey and monitoring methods could be time-consuming and costly. Sampling strategies of plant patches are effective in sampling procedures that cause minimizing sampling variance and time. In this study, for decreasing sampling time and cost, increasing speed, plant patches parameters (including length, width, height, area, and distance between the patches) were compared. Three transects with 50 m length at three aspect slopes were located randomly systematic at the selected site with different grazing intensities. Soil samples for nitrate (NO₃^?), total nitrogen (TN), ammonium (NH₄⁺), phosphorus (P), sodium absorption ration (SAR), soil acidity or soil reaction (pH), sodium (Na), electrical conductivity (EC), organic carbon (OC), and potassium (K) content were taken in these transects. The data were subjected to analysis of variance (ANOVA), and the average of the measured parameters in the transects was compared by Duncan Multiple Range test using SPSS₁₆ software. The soil characteristics compared between the regions were analyzed with Discriminant Function Analysis using STATISTICA₁₀ software. Results showed that the transect slope aspect and soil characteristics had an effect on measured parameters. It was suggested to withdraw the located transect at one of the North or South and West or East Slope aspects for increasing sampling efficiency. It was also suggested that to avoid time consumtion, sampling can be recorded on plant patches’ width instead of area. It is also suggested that it would be better to record the length of the plant patches instead of their area in the non-grazed zones and record the length and the width of the plant patches in the moderate- and the high-grazed zones.