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Field experiments were set up in order to evaluate the yield response of quinoa (Chenopodium quinoa Willd. cv. Titicaca) to irrigation with saline and fresh water under Mediterranean climate from 2010 to 2012 in Adana, Turkey. Irrigation treatments in 2010 and 2011 comprised full irrigation with fresh water, full irrigation with saline water of different salt concentrations (40, 30, 20, 10 dS m–1), deficit irrigations with fresh water (50%, 75% of full irrigation), partial root-zone drying, and deficit irrigation with saline water of 40 dS m–1 (50%). In 2012, in addition to the full irrigation treatments, two deficit irrigation levels of 67% and 33% of full irrigation with fresh or saline (30, 20, 10 dS m–1) water were considered. The results indicated that grain yields were slightly reduced by irrigation water salinity up to 30 dS m–1 compared with fresh water irrigation. Salinity and drought stress together interfered considerably with crop grain and biomass yields. However, salinity stress alone did not interfere with grain and biomass yield significantly; therefore, quinoa may be defined as a crop tolerant to salinity. Yield parameters such as aboveground biomass, seed yield and harvest index suggested a good adaptation of quinoa cv. Titicaca to Mediterranean environments.
This study quantifies the responses of drought-tolerant genotypes of chickpea (Cicer arietinum L.) to water availability under three irrigation regimes: rainfed (T1), 30% of full supplemental irrigation (T2), and full supplemental irrigation (T3). Sixteen genotypes of chickpea were tested in a split-plot arrangement in a randomised complete block design with three replications. Drought-resistance score (DRS), days to 50% flowering, plant height, days to maturity (DTM), grain yield (GY), biological yield (BY), 100-seed weight, average number of pods per plant (PoN), and average number of seeds per plant (SN) were measured. ANOVA indicated significant differences between treatments, years, and genotypes. Two genotypes, FLIP03-145C and ILC588, showed high drought tolerance accompanied by lower DTM, and they produced the highest GY (9.3 g plant–1). Strong and significant (P < 0.001) correlations were observed between GY and BY (0.94), SN (0.93), and PoN (0.94). The GY, BY, SN, and PoN traits were significantly (P < 0.001) correlated with DRS (–0.51 to –0.58). Ten genotypes performed better under T2 than T3, indicating a limitation in response to more water availability. Three genotypes (FLIP03-145C, ILC3182, and ILC588) are recommended for the national programs of Mediterranean countries as being drought-tolerant and especially responsive to water.
Drought is a major limiting factor in faba bean (Vicia faba L.) production in the Mediterranean region, which is known for its irregular water distribution and moderate moisture levels (∼500 mm rainfall). In this study, faba bean genotypes were evaluated for spectral indices, yield traits, rhizobium nodulation and yield stability under diverse environments, and their relationships. Eleven faba bean genotypes were evaluated under two water regimes, rainfed and supplemental irrigation (SI), in 2008–09; and under three water regimes (rainfed, 50% and 100% soil water capacity irrigation) for three consecutive growing seasons (2009–10, 2010–11, 2011–12), at Tel Hadya in Syria. They were also evaluated at Terbol in Lebanon for one season (2011–12) in a split-plot experiment with three irrigation treatments and at Kfardan in Lebanon for two seasons, 2008–09 (rainfed) and 2010–11 (rainfed and SI). The genotypes included three cultivars and eight drought-tolerant breeding lines selected at <300 mm annual rainfall. Phenological and morphological traits were recorded, as well as nodule weight per plant, grain yield, biological yield and spectral reflectance indices. Data were statistically analysed for each year. There were significant genotypic differences for seed yield under SI and rainfed conditions in 2008–09, and full irrigation in 2009–10 and 2011–12. Days to flowering and maturity were significantly different among genotypes for rainfed and irrigated conditions. There were significant differences between water regimes and genotypes, but their interactions were not significant. FLIP06-010FB was the highest yielding and most stable among the tested genotypes across different environments. Days to flowering and days to maturity were positively correlated with grain yield. The spectral indices structure-insensitive pigment index and normalised pheophytinisation index were found to correlate positively with grain yield and could therefore be used for selection under drought-prone environments.
Durum wheat production in southern Australia is limited when water deficit occurs immediately before and during anthesis. This study was conducted to determine the effect of genotypic variation on various yield, morphological and physiological responses to pre-anthesis water-deficit stress by evaluating 20 durum wheat (Triticum turgidum L. ssp. durum) genotypes over 2 years of glasshouse experiments. Grain number was the major yield component that affected yield under pre-anthesis water-deficit stress. Genotypes with less yield reduction also had less reduction in chlorophyll content, relative water content and leaf water potential, suggesting that durum genotypes tolerant of water-deficit stress maintain a higher photosynthetic rate and leaf water status. Weak to moderate positive correlations of morphological traits, including plant height and fertile tiller number, with grain number and biomass make the evaluation of high-yielding genotypes in rainfed conditions possible. Morphological traits (such as plant height and tiller number) and physiological traits (such as chlorophyll content, relative water content and leaf water potential) could therefore be considered potential indicators for indirect selection of durum wheat with water-deficit stress tolerance under Mediterranean conditions.
White clover (Trifolium repens L.) is an important pasture legume in temperate areas throughout the world, providing fodder for grazing animals and improving soil fertility via symbiotic nitrogen fixation. However, the persistence and stress tolerance of white clover is affected by several viruses, chiefly Alfalfa mosaic virus (AMV), Clover yellow vein virus (ClYVV) and White clover mosaic virus (WClMV). Efforts to introgress natural forms of virus resistance from other Trifolium spp. into white clover and lucerne (alfalfa) have had only limited success. This has been addressed by developing white clover germplasm exhibiting viral-coat-protein-mediated resistance to AMV and non-transgenic resistance to ClYVV. This report describes PCR-based assays for detecting the transgenes associated with the H6 transformation event in seeds, fresh leaves, air-dried leaves and mixtures of air-dried herbage of white clover and perennial ryegrass (hay). Although further development is required to convert these assays for use in the field, this paper demonstrates the ability to detect these transgenes in a range of agricultural products associated with the commercial use of white clover.
The use of grasses such as ryegrass and fescues infected with endophytic fungi of the Epichloë genus is widespread in New Zealand’s pastoral systems. Each endophyte–cultivar combination represents a distinctive genome–genome association, resulting in unique biological outcomes. The wider influence of these interactions on rhizosphere microbiology are not well characterised. This is important, because there may be opportunities or risks associated with selective disruption of the rhizosphere microbiota. We explored the interaction of two commercially used endophyte fungi, E. festucae var. lolii strains AR1 and AR37, within a genetically uniform breeding line of perennial ryegrass (Lolium perenne cv. Samson 11104) on the rhizosphere metabolome and the composition of the fungal, bacterial, and Pseudomonas communities. There were strong differences in the rhizosphere metabolomes between infested and non-infested ryegrass strains (P = 0.06). These were attributed to shifts in various n-alkane hydrocarbon compounds. The endophyte-associated alteration in rhizosphere metabolome was linked to changes in the total bacterial (P < 0.01) and fungal (P < 0.05) rhizosphere communities. Furthermore, there was varying levels of support for endophyte-specific (AR1 v. AR37) impacts on the bacterial and fungal communities. Pseudomonas bacterial communities were not influenced by endophyte infection of ryegrass (P = 0.834).
Jatinder Kaur, Piyumi N. Ekanayake, Pei Tian, Eline van Zijll de Jong, Mark P. Dobrowolski, Simone J. Rochfort, Ross C. Mann, Kevin F. Smith, John W. Forster, Kathryn M. Guthridge, German C. Spangenberg
Asexual fungal endophytes of the genus Epichloë form mutually beneficial associations with cool-season pasture grasses such as ryegrasses (Lolium spp.). Alkaloid production by the fungus confers both beneficial (deterrence of invertebrate herbivory) and detrimental (toxicity to mammalian livestock) attributes. A few novel strains with desirable metabolite profiles have been advanced into commercial production by inoculation of perennial ryegrass cultivars. In the present study, an integrated process for discovery of novel endophytes based on exploitation of genotypic information has been designed and implemented. A survey of genetic diversity was performed on a large-scale, customised germplasm collection (containing 244 accessions) in order to identify previously uncharacterised endophyte genotypes. Preliminary qualitative metabolic profiling in the endogenous genetic background permitted elimination of undesirable combinations, and definition of a subset of priority candidates. A novel method was developed for inoculation of endophytes into meristem-culture-derived callus tissue of single genotypes from multiple perennial ryegrass cultivars, in order to allow isogenic comparisons with respect to both host and endophyte genotype. Beneficial toxin profiles were confirmed for associations formed with the grass genotypic panel, and semi-quantitative metabolite analysis provided evidence for genotype-specific effects of both host and genotype on levels of alkaloid production. Vegetative stability was also assessed over both shorter and longer terms. A final set of three prioritised candidates was obtained, two of which (belonging to the known taxa E. festucae var. lolii and LpTG-2) produce the alkaloids ergovaline and peramine. The third candidate endophyte, belonging to a putative novel taxon, solely produces representatives of an additional alkaloid class, the epoxy-janthitrems.
Chicory (Cichorium intybus L.) and narrow-leaved plantain (Plantago lanceolata L.) are capable of producing a large amount of high quality feed during summer. Like many species, grazing management decisions influence their dry matter (DM) production. One of the factors implicated in the grazing-management effect on yield of other forages are plant non-structural carbohydrate (NSC) or nitrogen (N) reserves. The aim of this experiment was to characterise the patterns of NSC and N reserve depletion and replenishment for chicory and plantain during a 35-day regrowth cycle in summer, and investigate the impact of residual height on NSC and N reserves. In chicory roots, the NSC concentration tended (P = 0.09) to decline for 7 days post-defoliation before replenishment began and pre-defoliation concentrations were attained by Day 21 of regrowth (310 growing degree-days; GDD). Similarly, the amount of NSC in plantain roots declined for 14 days post-defoliation (P < 0.001), increasing again from Day 21 and with full replenishment to pre-defoliation levels by Day 35 of regrowth (532 GDD). The two residual heights tested (30 and 60 mm) had minimal impact on NSC reserves during regrowth in either chicory or plantain, likely because the majority of NSC reserves are stored in the roots rather than the stubble. In other plant species, a failure to replenish NSC reserves before the next defoliation is one factor associated with reduced DM production. This also appears to be the case with chicory and plantain, with reductions in DM production occurring if swards are defoliated during NSC mobilisation or the early stages of replenishment (i.e. before 21 days of regrowth or 310 GDD in chicory and 35 days of regrowth or 532 GDD in plantain).
Raphanus raphanistrum is a problematic weed, which has become increasingly difficult to control in Australian cropping regions. In 2010, a random survey was conducted across 14 million ha of the Western Australian grain belt to establish the frequency of herbicide resistance in R. raphanistrum and to monitor the change in resistance levels by comparing results with a previous survey in 2003. Screening R. raphanistrum populations with herbicides commonly used to control this weed revealed that most populations (84%) contained individual plants resistant to the acetolactate synthase-inhibiting herbicide chlorsulfuron, whereas 49% of populations also had plants resistant to the imidazolinone herbicides. Resistance to other mode of action herbicides (2,4-D (76%) and diflufenican (49%)) was also common. Glyphosate, atrazine and pyrasulfotole bromoxynil remained effective on most R. raphanistrum populations. These results demonstrate that resistance to some herbicides has increased significantly since 2003 when the values were 54% for chlorsulfuron and 60% for 2,4-D; therefore, a wide range of weed management options that target all phases of the cropping program are needed to sustain these cropping systems in the future.
Here, two types of smart irrigation controllers intended to reduce irrigation water are investigated under Saudi Arabia’s present water crisis scenario. These controllers are specially made for scheduling irrigation and management of landscaping. Consequently, the aim of this study is to adapt the efficient automated controllers to tomato crops, and for extension to other similar agricultural crops. The controllers are based on evapotranspiration and have been shown to be promising tools for scheduling irrigation and quantifying the water required by plants to achieve water savings. In particular, the study aims to evaluate the effectiveness of these technologies (SmartLine SL 1600and Hunter Pro-C) in terms of the amount of irrigation applied and compare them with conventional irrigation scheduling methods. The smart irrigation systems were implemented and tested under drip irrigation and subsurface irrigation for tomato (cv. Nema) in an arid region. The results revealed significant differences between the three irrigation-scheduling methods in both the amount of applied water and yield. For example, each 1 mm water depth applied to the tomato crop via subsurface (or drip) irrigation by SmartLine, Hunter Pro-C, and the control system yielded 129.70 kg (70.33 kg), 161.50 kg (93.47 kg), and 109.78 kg (108.32 kg), respectively. Generally, the data analysis indicates that the Hunter Pro-C system saves water and produces a higher yield with the greatest irrigation water-use efficiency (IWUE) of the irrigation scheduling methods considered. Moreover, the results indicate that the subsurface irrigation system produced a higher yield and IWUE than the drip system.
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