Responses of faba bean (Vicia faba L.) yield parameters to heat stress treatments for five days during floral development and anthesis

Experiments were conducted over two years to quantify the response of faba bean (Vicia faba L.) to heat stress. Potted winter faba bean plants (cv. Wizard) were exposed to temperature treatments (18/10; 22/14; 26/18; 30/22; 34/26°C day/night) for five days during floral development and anthesis. Developmental stages of all flowers were scored prior to stress, plants were grown in exclusion from insect pollinators to prevent pollen movement between flowers, and yield was harvested at an individual pod scale, enabling effects of heat stress to be investigated at a high resolution. Susceptibility to stress differed between floral stages, flowers were most affected during initial green-bud stages. Yield and pollen germination of flowers present before stress showed threshold relationships to stress, with lethal temperatures (t50) ~28°C and ~32°C, while whole plant yield showed a linear negative relationship to stress with high plasticity in yield allocation, such that yield lost at lower nodes was partially compensated at higher nodal positions. Faba bean has many beneficial attributes for sustainable modern cropping systems but these results suggest that yield will be limited by projected climate change, necessitating the development of heat tolerant cultivars, or improved resilience by other mechanisms such as earlier flowering times

Effect of interactions between heat stress and insect pollination on faba bean (Vicia faba L.) yield production

We exposed potted faba bean plants to heat stress for 5 days during floral development and anthesis. Temperature treatments were representative of heat waves projected in the UK for the period 2021-2050 and onwards. Following temperature treatments, plants were distributed in flight cages and either pollinated by domesticated Bombus terrestris colonies or received no insect pollination. The dataset contains various measurements taken from experimental faba bean (Vicia faba L.) plants over three years of experiments conducted at the University of Reading Plant Environment Laboratory (latitude 51 27’ N, longitude 00 56’ W) in controlled environment chambers and insect pollination cages. All measurements were conducted once plants had reached senescence. For the experimental rationale and methodology, please see J. Bishop, et al., Insect pollination reduces yield loss following heat stress in faba bean (Vicia faba L.). Agric. Ecosyst. Environ. 2015. http://dx.doi.org/10.1016/j.agee.2015.12.007

Measures of cross-pollination and yield production of faba bean (Vicia faba L.) in response to heat stress and insect pollination treatments

Datasets relating to two experiments measuring cross-pollination and yield production of faba bean (Vicia faba L, cultivar Wizard) in response to heat stress and insect pollination treatments. This accompanies the paper titled 'Elevated temperature drives a shift from selfing to outcrossing in the insect pollinated legume, faba bean (Vicia faba).' Journal of Experimental Botany. Bishop J, Jones HE, O'Sullivan DM, Potts SG. (In press). Potted faba bean plants were exposed to either heat stress (30/24°C day/night temperature, 16 hour photoperiod) or control (20/14°C) treatments for five days during floral development and anthesis. These plants were then either i) moved to mesh cages that either contained bumblebees or were empty, or ii) moved to two field sites and either left open to allow visitation by wild insect pollinators, or enclosed individually in mesh bags. Cross-pollination was assessed using a morphological marker. Both the mesh cages and field contained pollen donor plants that were homozygous for a dominant 'dark hilum' trait. The experimental plants were homozygous for a recessive 'light hilum' trait. Thus, by observing which colour hila the experimental progeny produced, it was possible to identify individuals that had been sired by the pollen donor plants. Yield production parameters were assessed on the experimental plants at senescence. The effects of individual mesh bags used to exclude insect pollinators in the field experiment were established using two separate experiments. Separate groups of plants were either i) all bagged at the field sites, with a subset of flowers hand pollinated to establish the effect of bagging on yield production per flower while maximizing pollination, or ii) housed within a large mesh cage to exclude all insect pollinators, then either bagged or unbagged at the same time as the field experiment was conducted, with whole plant yield parameters then measured at senescence

A Controlled Study of the Flipped Classroom With Numerical Methods for Engineers

Recent advances in technology and ideology have unlocked entirely new directions for education research. Mounting pressure from increasing tuition costs and free, online course offerings are opening discussion and catalyzing change in the physical classroom. The flipped classroom is at the center of this discussion. The flipped classroom is a new pedagogical method, which employs asynchronous video lectures, practice problems as homework, and active, group-based problem-solving activities in the classroom. It represents a unique combination of learning theories once thought to be incompatible—active, problem-based learning activities founded upon constructivist schema and instructional lectures derived from direct instruction methods founded upon behaviorist principles. The primary reason for examining this teaching method is that it holds the promise of delivering the best from both worlds. A controlled study of a sophomore-level numerical methods course was conducted using video lectures and model-eliciting activities (MEAs) in one section (treatment) and traditional group lecture-based teaching in the other (comparison). This study compared knowledge-based outcomes on two dimensions: conceptual understanding and conventional problem-solving ability. Homework and unit exams were used to assess conventional problem-solving ability, while quizzes and a conceptual test were used to measure conceptual understanding. There was no difference between sections on conceptual under- standing as measured by quizzes and concept test scores. The difference between average exam scores was also not significant. However, homework scores were significantly lower by 15.5 percentage points (out of 100), which was equivalent to an effect size of 0.70. This difference appears to be due to the fact that students in the MEA/video lecture section had a higher workload than students in the comparison section and consequently neglected to do some of the homework because it was not heavily weighted in the final course grade. A comparison of student evaluations across the sections of this course revealed that perceptions were significantly lower for the MEA/video lecture section on 3 items (out of 18). Based on student feedback, it is recommended that future implementations ensure tighter integration between MEAs and other required course assignments. This could involve using a higher number of shorter MEAs and more focus on the early introduction of MEAs to students

Insect pollination reduces yield loss following heat stress in faba bean (Vicia faba L.)

Global food security, particularly crop fertilization and yield production, is threatened by heat waves that are projected to increase in frequency and magnitude with climate change. Effects of heat stress on the fertilization of insect-pollinated plants are not well understood, but experiments conducted primarily in self-pollinated crops, such as wheat, show that transfer of fertile pollen may recover yield following stress. We hypothesized that in the partially pollinator-dependent crop, faba bean (Vicia faba L.), insect pollination would elicit similar yield recovery following heat stress. We exposed potted faba bean plants to heat stress for 5 days during floral development and anthesis. Temperature treatments were representative of heat waves projected in the UK for the period 2021-2050 and onwards. Following temperature treatments, plants were distributed in flight cages and either pollinated by domesticated Bombus terrestris colonies or received no insect pollination. Yield loss due to heat stress at 30°C was greater in plants excluded from pollinators (15%) compared to those with bumblebee pollination (2.5%). Thus, the pollinator dependency of faba bean yield was 16% at control temperatures (18 to 26°C) and extreme stress (34°C), but was 53% following intermediate heat stress at 30°C. These findings provide the first evidence that the pollinator dependency of crops can be modified by heat stress, and suggest that insect pollination may become more important in crop production as the probability of heat waves increases

Elevated temperature drives a shift from selfing to outcrossing in the insect pollinated legume, faba bean (Vicia faba)

Climate change can threaten the reproductive success of plants, both directly, through physiological damage during increasingly extreme weather events, and indirectly, through disruption of plant–pollinator interactions. To explore how plant–pollinator interactions are modified by extreme weather, we exposed faba bean (Vicia faba) plants to elevated temperature for 5 d during flowering, simulating a heatwave. We then moved the plants to flight cages with either bumblebees or no pollinators, or to two field sites, where plants were enclosed in mesh bags or pollinated by wild insect communities. We used a morphological marker to quantify pollen movement between experimental plants. There was a substantial increase in the level of outcrossing by insect pollinators following heat stress. Proportion outcrossed seed increased from 17 % at control temperature to 33 % following heat stress in the flight cages, and from 31 % to 80 % at one field site, but not at the other (33 % to 32 %). Abiotic stress can dramatically shift the relative contributions of cross- and self-pollination to reproduction in an insect pollinated plant. The resulting increases in gene flow have broad implications for genetic diversity and functioning of ecosystems, and may increase resilience by accelerating the selection of more stress-tolerant genotypes