Injury to oilseed rape caused by mirid bugs (Lygus) (Heteroptera: Miridae) and its effect on seed production

Injury by Lygus spp. to oilseed rape, Brassica napus L. and Brassica campestris L., was assessed based on laboratory and field studies in Alberta, Canada. The visible injuries consisted of lesions on the surfaces of stems, buds, flowers and pods similar to those described for other crops. They caused buds and flowers to abscise and seeds to collapse, and reduced the weight of healthy seeds produced per pod. The plants compensated for bud loss so that no net reduction in the number of pods occurred. However, in some situations the damage to buds resulted in a reduced seed yield that increased with the amount of injury. The plants also compensated for flower loss so that no net reduction in the number of pods occurred, but seed yield declined as injury increased. Plants did not compensate for seeds that collapsed as a result of lygus feeding. The feeding activity of lygus bugs reduced seed yield in oilseed rape.     

The competitive effects of volunteer barley (Hordeum vulgare) on the growth of oilseed rape (Brassica napus)

The effects of competition from volunteer barley (Hordeum vulgare) on the growth and yield of oilseed rape (Brassica napus) were investigated in four experiments over three seasons. The growth of rape in the autumn was reduced by 50 - 91 % by competition from 400 barley plants m^-2. A lower barley density of 200 plants m^-2 had less effect but still reduced growth of rape by 65 - 81% in two of the experiments and 25 - 40% in the other two. During winter and spring the barley decreased in vigour and in the spring the rape started to recover, especially on the early drilled (23 - 30 August) plots. The rape sown in mid-September recovered less quickly. In Experiment 3, herbicides applied in November to control barley did not result in increased growth of rape in winter but led to greater recovery in spring. The barley died during the winter in Experiments 2 and 4, even in the absence of herbicides. Despite the marked effects of barley on the growth of rape in the autumn, yields on plots that had previously contained 200 barley plants m^-2 were reduced by a maximum of only 16% in three of the experiments. In Experiment 3, where the barley was most competitive, this density and 400 plants m^-2 lowered yields by 39% and 78%, respectively. Where a herbicide was used in November to control the barley these yield losses were reduced to 5%. In many rape crops the cost of herbicide treatment would be greater than the financial returns from the expected increase in yield resulting from the control of weeds. Possible reasons for the small loss in yield of rape from barley densities that had substantial effects on the growth of rape in the autumn are discussed.     

两个油菜种对水分胁迫的适应方式

本文报道了2个油菜种对水分胁迫的适应方式。研究表明:芥菜型油菜对水分胁迫的适应性强于甘蓝型。其主要原因是由于形态方面的抗旱性,包括发育良好的根系,较厚的蜡质关闭了气孔。同时芥菜型油菜能将其余部分的水分调用到生长区而免遭旱害。甘蓝型油菜叶水势下降快,在相同水势下其相对电导值低于芥菜型。同时还观察了2个种在干旱条件下叶绿体与其基粒的变化。总之,芥菜型具典型的高水势耐旱特性,而甘蓝型具低水势耐旱特性。     

The scale characteristics of two Aphanius species from southern Iran (Teleostei: Aphaniidae)

Fish scales are morphologically diverse among species, within species, and even among individuals. The present study investigated macro- and micromorphology of the scales between two closely related Aphanius species in southern Iran including Aphanius hormuzensis, collected from Gotab/Mehran River and A. stoliczkanus, from Howba hot sulphuric spring. The results indicated clear interspecific differences in scale macromorphology and microstructures. The scales of A. hormuzensis are characterised by a rounded shape, 7–9 (mean 8.0±0.83) primary radii, and a relatively large focus with oblong shape that positioned centrally on the scale, while the scales of A. stoliczkanus are characterised by a polygonal shape with few spines in posterior region, 8–11 (mean 10.0±0.78) primary radii and a small rounded focus that positioned posterocentraly on the scale. These species are morphologically close but clearly distinguished by their scale morphology and habitat requirements (e.g. water depth and food availability). Therefore, it can be assumed that clear differences in their scale morphology have been resulted by the combination of both genetic and environmental factors.     

Greenhouse gas emissions from the energy crop oilseed rape (Brassica napus); the role of photosynthetically active radiation in diurnal N2O flux variation

Oilseed rape (OSR, Brassica napus L.) is an important feedstock for biodiesel; hence, carbon dioxide (CO₂), methane (CH₄) and particularly fertilizer‐derived nitrous oxide (N₂O) emissions during cultivation must be quantified to assess putative greenhouse gas (GHG) savings, thus creating an urgent and increasing need for such data. Substrates of nitrification [ammonium (NH₄)] and denitrification [nitrate (NO₃)], the predominant N₂O production pathways, were supplied separately and in combination to OSR in a UK field trial aiming to: (i) produce an accurate GHG budget of fertilizer application; (ii) characterize short‐ to medium‐term variation in GHG fluxes; (iii) establish the processes driving N₂O emission. Three treatments were applied twice, 1 week apart: ammonium nitrate fertilizer (NH₄NO₃, 69 kg‐N ha^?1) mimicking the farm management, ammonium chloride (NH₄Cl, 34.4 kg‐N ha^?1) and sodium nitrate (NaNO₃, 34.6 kg‐N ha^?1). We deployed SkyLine2D for the very first time, a novel automated chamber system to measure CO_2, CH₄ and N₂O fluxes at unprecedented high temporal and spatial resolution from OSR. During 3 weeks following the fertilizer application, CH₄ fluxes were negligible, but all treatments were a net sink for CO₂ (ca. 100 g CO₂ m^?2). Cumulative N₂O emissions (ca. 120 g CO₂‐eq m^?2) from NH₄NO₃ were significantly greater (P < 0.04) than from NaNO₃ (ca. 80 g CO₂‐eq m^?2), but did not differ from NH₄Cl (ca. 100 g CO₂‐eq m^?2) and reduced the carbon sink of photosynthesis so that OSR was a net GHG source in the fertilizer treatment. Diurnal variation in N₂O emissions, peaking in the afternoon, was more strongly associated with photosynthetically active radiation (PAR) than temperature. This suggests that the supply of carbon (C) from photosynthate may have been the key driver of the observed diurnal pattern in N₂O emission and thus should be considered in future process‐based models of GHG emissions.     

Using lipidomics to reveal details of lipid accumulation in developing seeds from oilseed rape (Brassica napus L.)

With dwindling available agricultural land, concurrent with increased demand for oil, there is much current interest in raising oil crop productivity. We have been addressing this issue by studying the regulation of oil accumulation in oilseed rape (Brassica napus L). As part of this research we have carried out a detailed lipidomic analysis of developing seeds.The molecular species distribution in individual lipid classes revealed quite distinct patterns and showed where metabolic connections were important. As the seeds developed, the molecular species distributions changed, especially in the period of early (20 days after flowering, DAF) to mid phase (27DAF) of oil accumulation. The patterns of molecular species of diacylglycerol, phosphatidylcholine and acyl-CoAs were used to predict the possible relative contributions of diacylglycerol acyltransferase (DGAT) and phospholipid:diacylglycerol acyltransferase to triacylglycerol production. Our calculations suggest that DGAT may hold a more important role in influencing the molecular composition of TAG. Enzyme selectivity had an important influence on the final molecular species patterns.Our data contribute significantly to our understanding of lipid accumulation in the world's third most important oil crop.     

One gene‐one name: the AvrLmJ1 avirulence gene of Leptosphaeria maculans is AvrLm5

Leptosphaeria maculans, the causal agent of blackleg disease, interacts with Brassica napus (oilseed rape, canola) and other Brassica hosts in a gene‐for‐gene manner. The avirulence gene AvrLmJ1 has been cloned previously and shown to interact with an unidentified Brassica juncea resistance gene. In this study, we show that the AvrLmJ1 gene maps to the same position as the AvrLm5 locus. Furthermore, isolates complemented with the AvrLmJ1 locus confer avirulence towards B. juncea genotypes harbouring Rlm5. These findings demonstrate that AvrLmJ1 is AvrLm5 and highlight the need for shared resources to characterize accurately avirulence and/or resistance genes.     

Simulating the onset of spring vegetation growth across the Northern Hemisphere

Changes in the spring onset of vegetation growth in response to climate change can profoundly impact climate–biosphere interactions. Thus, robust simulation of spring onset is essential to accurately predict ecosystem responses and feedback to ongoing climate change. To date, the ability of vegetation phenology models to reproduce spatiotemporal patterns of spring onset at larger scales has not been thoroughly investigated. In this study, we took advantage of phenology observations via remote sensing to calibrate and evaluated six models, including both one‐phase (considering only forcing temperatures) and two‐phase (involving forcing, chilling, and photoperiod) models across the Northern Hemisphere between 1982 and 2012. Overall, we found that the model that integrated the photoperiod effect performed best at capturing spatiotemporal patterns of spring phenology in boreal and temperate forests. By contrast, all of the models performed poorly in simulating the onset of growth in grasslands. These results suggest that the photoperiod plays a role in controlling the onset of growth in most Northern Hemisphere forests, whereas other environmental factors (e.g., precipitation) should be considered when simulating the onset of growth in grasslands. We also found that the one‐phase model performed as well as the two‐phase models in boreal forests, which implies that the chilling requirement is probably fulfilled across most of the boreal zone. Conversely, two‐phase models performed better in temperate forests than the one‐phase model, suggesting that photoperiod and chilling play important roles in these temperate forests. Our results highlight the significance of including chilling and photoperiod effects in models of the spring onset of forest growth at large scales, and indicate that the consideration of additional drivers may be required for grasslands.     

A lotic‐breeding salamander (Hynobius kimurae) modifies physiological and morphological traits during wintering

Unlike other migratory salamanders, Hynobius kimurae moves to aquatic hibernacula during fall. Does submergence into water during fall induce changes in physiological and morphological traits? We investigated whether such changes occur in both sexes from the entrance into the water (November) to the exit from the water (May) in the laboratory. Mean duration of stay in the water was 21.7 weeks in males and 19.0 weeks in females. Spermiation began 13.8 weeks after the males entered the water. Sperm storage lasted for 6.3 weeks. Spawning occurred 18.3 weeks after the females entered the water. Cloacae swelled greatly soon after the sexes entered the water. In males after entering the water, tail shape changed from sticklike to finlike. Although physiological and morphological traits in other species change simultaneously in both the submergence into water and the onset of breeding activity only during spring, such changes occurred in individual H. kimurae firstly during fall (shortly after entering the water) and secondly during spring (shortly after awaking from hibernation). This difference suggests that these two‐step changes during a prolonged period (fall–spring) are concentrated in a short period of aquatic‐breeding activity during spring in other species with terrestrial hibernation and associated reproductive cycles.