Grain yield responsiveness to water supply in near-isogenic reduced-tillering wheat lines – an engineered crop trait near its upper limit

Grain yield responsiveness to water supply was evaluated in spring wheat (Triticum aestivum L.) near-isogenic lines (NILs) for presence of the reduced-tillering ‘tin’ (tiller inhibition) gene using boundary-line analysis. Data were collected from multiple seasons at Managed Environment Facilities (MEFs; field experimental facilities to control and target water supply) at three locations across the Australian wheatbelt. The minimum water required to obtain a measurable yield was less in reduced-tillering than free-tillering NILs (70 vs 95 mm). Above this minimum, for every mm increase in water supply, grain yield in free-tillering lines increased more rapidly (that is, showed greater responsiveness) than reduced-tillering lines (15.4 vs 12.6 kg ha−1 mm−1). This difference suggests the reduced-tillering gene is associated with greater yield potential in situations with water supply of less than 200 mm. Reduced-tillering wheat also affords a 0.3 t ha−1 yield benefit in extremely water-limited, low yielding situations where no measurable yield is expected with free-tillering wheats (i.e. at water supply 95 mm). These specific adaptations need to be considered when contemplating the use of reduced-tillering wheats in dryland systems where water is a key limiting factor. © 2018 Elsevier B.V

Crop rotation options for dryland agriculture: An assessment of grain yield response in cool-season grain legumes and canola to variation in rainfall totals

Crop production in dryland systems is mainly dependent on water availability from rainfall which is highly variable between years and locations. We employed the widely used boundary-line analysis, with an existing industry dataset from across the Australian dryland cropping regions, to investigate the relative sensitivity of grain yield in canola (Brassica napus L.), chickpea (Cicer arietinum L.), faba bean (Vicia faba L.), field pea (Pisum sativum L.), lentil (Lens culinaris L.), and narrow-leafed lupin (Lupinus angustifolius L.) to variation in rainfall totals. Chickpea had the lowest non-productive water use, was more responsive to water supply, and reached its maximum yield at a lower water supply than the other species. In contrast canola had the highest non-productive water use, was less responsive to water supply, and reached its maximum yield at a higher water supply than the other species. These results suggest that chickpea offers the most stable outcome, and canola the greatest variation, in response to the variability in rainfall totals between years and locations. © 2019 Elsevier B.V

Can elevated CO2 buffer the effects of heat waves on wheat in a dryland cropping system?

Increasing atmospheric CO2 concentration [CO2] drives the rise in global temperatures, with predictions of an increased frequency of heat waves (short periods of high temperatures). Both, CO2 and high temperature, have profound effects on wheat growth and productivity. We tested whether elevated [CO2] (eCO2) has a potential to ameliorate the effects of simulated heat waves (HT) on wheat in a dryland cropping system. Wheat was field-grown at the Australian Grains Free Air CO2 Enrichment (AGFACE) facility under ambient [CO2] (∼390 ppm) or eCO2 (∼550 ppm) for two growing seasons, one with ample water supply and one of severe drought. Using heated chambers, heat waves (3-day periods of high temperatures) were imposed at critical growth stages before anthesis (HT1) or post-anthesis (HT2, HT3). Gas exchange, chlorophyll content and concentration of nitrogen (N) in mainstem flag leaves, as well as concentrations of stem water-soluble carbohydrates (WSC) in mainstems were monitored throughout the season. Yield, biomass and thousand kernel weights (TKW) were measured at maturity. Elevated [CO2] moderated the effect on net CO2 assimilation rates of pre-anthesis (HT1), but not of post-anthesis heat waves (HT2, HT3). Growth under eCO2 increased stem WSC both, with and without experimental heat waves, but remobilisation decreased significantly under heat indicating that a greater WSC pool does not necessarily translate into greater remobilisation into the grain. Grain yield (g m−2) was greater under eCO2 and especially pre-anthesis heat stress decreased grain yield in the wetter season, and this decrease was stronger under eCO2 (up to 20%) than under aCO2 (up to 10%). Grain N decreased under eCO2, but less so under heat stress. We conclude that eCO2 may moderate some effects of heat stress in wheat but such effects strongly depend on seasonal conditions and timing of heat stress. © 2018 Elsevier B.V

Trade-offs between water-use related traits, yield components and mineral nutrition of wheat under Free-Air CO₂ Enrichment (FACE)

Tausz, M ORCiD: 0000-0001-8205-8561This study investigated trade-offs between parameters determining water use efficiency of wheat under elevated CO2 in contrasting growing seasons and a semi-arid environment. We also evaluated whether previously reported negative relationships between nutrient content and transpiration efficiency among wheat genotypes will be maintained under elevated CO2 conditions. Two cultivars of wheat (Triticum aestivum L.), Scout and Yitpi, purportedly differing in water use efficiency related traits (e.g. transpiration efficiency) but with common genetic backgrounds were studied in a high yielding, high rainfall (2013), and in a low yielding, very dry growing season (2014) under Free-Air CO2 Enrichment (FACE, CO2 concentration of approximately 550 μmol mol-1) and ambient (approximately 390 μmol mol-1) CO2. Gas exchange measurements were collected diurnally between stem elongation and anthesis. Aboveground biomass and nutrient content (sum of Ca, K, S, P, Cu, Fe, Zn, Mn and Mg) were determined at anthesis. Yield, yield components and harvest index were measured at physiological maturity. Cultivar Scout showed transiently greater transpiration efficiency (measured by gas exchange) over cultivar Yitpi under both ambient and elevated CO2 conditions, mainly expressed in the high yielding but not in the low yielding season. Nutrient content was on average 13% greater for the lower transpiration efficiency cultivar Yitpi than the cultivar with higher transpiration efficiency (Scout) in the high yielding season across both CO2 concentrations. Elevated CO2 stimulated grain yield to a greater extent in the high yielding season than in the low yielding season where increased aboveground biomass earlier in the season did not translate into fertile tillers in cultivar Yitpi. Yield increased 27 and 33% in the high yielding and 0 and 19% in the low yielding season for cultivars Yitpi and Scout, respectively. Intraspecific variation in CO2 responsiveness related mechanisms of grain yield were observed. These results suggest CO2-driven trade-offs between traits governing water use efficiency are related to both growing season and intraspecific variations, and under very dry finishes, the trade-offs may even reverse. The negative relationship between nutrient content and transpiration efficiency among wheat genotypes will be maintained under elevated CO2 conditions. © 2016 Elsevier B.V

The relationship between transpiration and nutrient uptake in wheat changes under elevated atmospheric CO2

The impact of elevated [CO2] (e[CO2]) on crops often includes a decrease in their nutrient concentrations where reduced transpiration-driven mass flow of nutrients has been suggested to play a role. We used two independent approaches, a free-air CO2 enrichment (FACE) experiment in the South Eastern wheat belt of Australia and a simulation study employing the agricultural production systems simulator (APSIM), to show that transpiration (mm) and nutrient uptake (g m−2) of nitrogen (N), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg) and manganese (Mn) in wheat are correlated under e[CO2], but that nutrient uptake per unit water transpired is higher under e[CO2] than under ambient [CO2] (a[CO2]). This result suggests that transpiration-driven mass flow of nutrients contributes to decreases in nutrient concentrations under e[CO2], but cannot solely explain the overall decline. © 2017 Scandinavian Plant Physiology Societ

In vivo Antibacterial and Wound Healing Activities of Roman Chamomile (Chamaemelum nobile)

BACKGROUND: Today considerable number of drugs are produced from plants. Several plants with antibacterial and healing applications are used in medicine such as Roman chamomile (Chamaemelum nobile L.). Wound infection is one of the most prevalent infections among infectious diseases around the world. Due to appearance of drug resistance, researchers are now paying attention to medicinal plants. Therefore, this study was designed to investigate the antimicrobial and wound healing properties of C. nobile against Pseudomonas aeruginosa using in vivo conditions. METHODS: Ethanolic extract of C. nobile was provided using standard method. The 5 C. nobile ointment was prepared by dissolving lyophilized extract in eucerin. Forty five male rats were obtained from Ilam university. After anesthetization and wound creation, wounds were infected by P. aeruginosa. The rats were divided into three groups, group I was treated with C. nobile ointment, group II was treated with tetracycline ointment and the third group was treated with base gel as control group. RESULTS: Antibacterial and wound healing activities of C. nobile ointment were more than tetracycline ointment significantly. Our results indicated that extract of C. nobile had effective antibacterial activity and accelerated the progression of wound healing. CONCLUSION: Our study indicated that antibacterial and wound healing activities of C. nobile ointment were notable. C. nobile therapy in combination with antibiotics can also be useful because medicinal plants contents operate in synergy with antibiotics. These results revealed the value of plant extracts to control antibiotic resistant bacteria in wound infections

Trade-offs between water-use related traits, yield components and mineral nutrition of wheat under Free-Air CO2 Enrichment (FACE)

This study investigated trade-offs between parameters determining water use efficiency of wheat under elevated CO2 in contrasting growing seasons and a semi-arid environment. We also evaluated whether previously reported negative relationships between nutrient content and transpiration efficiency among wheat genotypes will be maintained under elevated CO2 conditions. Two cultivars of wheat (Triticum aestivum L.), Scout and Yitpi, purportedly differing in water use efficiency related traits (e.g. transpiration efficiency) but with common genetic backgrounds were studied in a high yielding, high rainfall (2013), and in a low yielding, very dry growing season (2014) under Free-Air CO2 Enrichment (FACE, CO2 concentration of approximately 550 μmol mol-1) and ambient (approximately 390 μmol mol-1) CO2. Gas exchange measurements were collected diurnally between stem elongation and anthesis. Aboveground biomass and nutrient content (sum of Ca, K, S, P, Cu, Fe, Zn, Mn and Mg) were determined at anthesis. Yield, yield components and harvest index were measured at physiological maturity. Cultivar Scout showed transiently greater transpiration efficiency (measured by gas exchange) over cultivar Yitpi under both ambient and elevated CO2 conditions, mainly expressed in the high yielding but not in the low yielding season. Nutrient content was on average 13% greater for the lower transpiration efficiency cultivar Yitpi than the cultivar with higher transpiration efficiency (Scout) in the high yielding season across both CO2 concentrations. Elevated CO2 stimulated grain yield to a greater extent in the high yielding season than in the low yielding season where increased aboveground biomass earlier in the season did not translate into fertile tillers in cultivar Yitpi. Yield increased 27 and 33% in the high yielding and 0 and 19% in the low yielding season for cultivars Yitpi and Scout, respectively. Intraspecific variation in CO2 responsiveness related mechanisms of grain yield were observed. These results suggest CO2-driven trade-offs between traits governing water use efficiency are related to both growing season and intraspecific variations, and under very dry finishes, the trade-offs may even reverse. The negative relationship between nutrient content and transpiration efficiency among wheat genotypes will be maintained under elevated CO2 conditions. © 2016 Elsevier B.V

Water use dynamics of dryland wheat grown under elevated CO2 with supplemental nitrogen

OnlinePublContext. Elevated atmospheric CO2 (e[CO2]) and nitrogen (N) fertilisation stimulate biomass and yield of crops. However, their interactions depend on crop growth stages and may affect water use dynamics. Aims and methods. This study investigated the interactive effects of two N rates, 0 and 100 kg N ha−1 , and two CO2 concentrations, ambient (a[CO2], ~400 μmol mol−1 ) and e[CO2] (~550 μmol mol−1 ), on biomass, yield and water use of two wheat cultivars, Wyalkatchem (N-use efficient) and Yitpi (local), using a free air CO2 enrichment facility. Key results. Elevated [CO2] stimulated leaf area (10%, P = 0.003) and aboveground biomass (11%, P = 0.03). In addition, e[CO2] reduced stomatal conductance (25%, P < 0.001) and increased net assimilation rates (12%, P < 0.001), resulting in greater (40%, P < 0.001) intrinsic water use efficiency. During early growth stages, e[CO2]resulted in higher water use than a[CO2]; however, this difference disappeared laterin the season, resulting in similar cumulative water use under both CO2 concentrations. Supplemental N stimulated grain yield of Yitpi by 14% while decreasing that of Wyalkatchem by 7% (N × cultivar, P = 0.063). With supplemental N, Yitpi maintained greater post-anthesis leaf N, chlorophyll content, canopy cover and net assimilation rate than Wyalkatchem. Conclusions. During early growth stages, the e[CO2]-induced stimulation of leaf-level water use efficiency was offset by greater biomass, resulting in higher water use. By the end of the season, similar cumulative water use under both CO2 concentrations indicates the dominating effect of the prevailing seasonal conditions in the study area. Observed yield responses of the studied cultivarsto supplemental N were associated with their ability to maintain post-anthesis photosynthetic capabilities. Implications. Our findings suggest that N-use efficiency traits and responsiveness need to be considered independently to optimise benefits from the ‘CO2 fertilisation effect’ through breeding.Shihab Uddin, Shahnaj Parvin, Roger Armstrong, Glenn J. Fitzgerald, Markus Löw, Alireza Houshmandfar, Ehsan Tavakkoli, Sabine Tausz-Posch, Garry J. O'Leary and Michael Taus