Chickpea Abiotic Stresses: Combating Drought, Heat and Cold

Chickpea is an important legume providing dietary proteins to both humans and animals. It also ameliorates soil nitrogen through biological nitrogen fixation. Drought, heat and cold are important factors among abiotic stresses limiting production in chickpea. Identification, validation and integration of agronomic, physiological and biochemical traits into breeding programs could lead to increased rates of genetic gain and the development of better adapted cultivars to abiotic stress conditions. This chapter illustrates the effects of stresses on chickpea growth and development. It also reviews the various traits and their relationship with grain yield under stress and proposes recommendation for future breeding

Modelling broccoli development, yield and quality

Broccoli is a vegetable crop of increasing importance in Australia, particularly in south-east Queensland and farmers need to maintain a regular supply of good quality broccoli to meet the expanding market. A predictive model of ontogeny, incorporating climatic data including frost risk, would enable farmers to predict harvest maturity date and select appropriate cultivar - sowing date combinations. To develop procedures for predicting ontogeny, yield and quality, field studies using three cultivars, 'Fiesta', 'Greenbelt' and 'Marathon', were sown on eight dates from 11 March to 22 May 1997, and grown under natural and extended (16 h) photoperiods at the University of Queensland, Gatton Campus. Cultivar, rather than the environment, mainly determined head quality attributes of head shape and branching angle. Yield and quality were not influenced by photoperiod. A better understanding of genotype and environmental interactions will help farmers optimise yield and quality, by matching cultivars with time of sowing. The estimated base and optimum temperature for broccoli development were 0 degrees C and 20 degrees C, respectively, and were consistent across cultivars, but thermal time requirements for phenological intervals were cultivar specific. Differences in thermal time requirement from floral initiation to harvest maturity between cultivars were small and of little importance, but differences in thermal time requirement from emergence to floral initiation were large. Sensitivity to photoperiod and solar radiation was low in the three cultivars used. This research has produced models to assist broccoli farmers in crop scheduling and cultivar selection in south-east Queensland

Cotton growth and yield dynamics across canopy layers in response to soil waterlogging

Due to an indeterminate growth habit, we hypothesised that different canopy layers of cotton might be variably influenced by soil waterlogging. The field-grown cotton cultivar (Sicot 71BRF) was waterlogged at early (WL, 77 days after planting [DAP]) and late reproductive phases (WL, 101 DAP) for 120 h. Data from different canopy layers e.g. bottom eight (MSN), middle five (MSN), and upper five main stem nodes (MSN) were collected 1 d (post-WL) and 7 d after termination of waterlogging (post-recovery). Both waterlogging events significantly reduced post-WL dry biomass, leaf N concentration and fruit development on MSN. In addition, WLearly significantly reduced photosynthesis and increased total soluble sugars (TSS) in the MSN and MSN leaves, although MSN leaves restored photosynthesis, N levels and TSS at recovery. It suggested that WL plants maintained photosynthesis of the upper leaves possibly by transporting N from the lower canopy leaves. Reduction (22%) in seed cotton yield under WL was the result of fruit loss from first position fruits of the upper and lower sympodial fruiting branches (FB and FB). Despite restoring the growth through improved photosynthesis and N supply, no yield recovery on FB suggested that the plants used these assimilates for growth of the established fruits. No significant yield reduction in response to WL suggested that the established cotton bolls were less sensitive to abscission across all canopy layers

Contribution of climate models and APSIM phenological parameters to uncertainties in spring wheat simulations: application of SUFI‐2 algorithm in northeast Australia

We used SUFI-2 for the first time to calibrate the phenology module of the APSIM-wheat model for 10 spring wheat cultivars cultivated in northeast Australia (south-eastern Queensland). Calibration resulted in an average root mean square error (RMSE) of 5.5 days for developmental stages from stem elongation up to flowering. Projections from 33 climate models under the representative concentration pathway 8.5 were used for simulations at 17 sites. Using adapted sowing times, we simulated significantly shorter crop cycles and grain yield improvements for the period 2036–2065 relative to 1990–2019 for three selected cultivars (Hartog, Scout and Gregory). Photoperiod and vernalisation sensitivities were shown to be the largest and smallest contributors to total uncertainties in the simulated flowering day and grain yield, respectively. Uncertainties in climate models had a relatively minor contribution to the total uncertainties in the simulated values of target traits. This contribution significantly increased when climate change impact on the target traits was quantified

Understanding of the Interactive Effect of Waterlogging and Shade on Cotton (Gossypium hirsutum L.) Growth and Yield

AbstractUnder the current climatic variability, extreme weather events with multiple stresses have become more frequent. Cotton, a relatively waterlogging sensitive crop, often experiences significant yield losses under persistent summer rainfall followed by extended cloudy weather. In two years of field experiments, we studied individual and interactive effects of soil waterlogging (WL) and shade on cotton growth and yield, hypothesising that low light conditions would amplify WL damage in cotton. The crop was exposed to WL, shade (50% reduction in photosynthetic photon flux) and WL + shade at peak flowering. Waterlogging was imposed by extending irrigation time from 8h to (96h and 120h, in 2012-13 and 2013-14, respectively), while the plants were shaded for 6 days or 9 days in 2012-13 and 2013-14, respectively. Waterlogging significantly inhibited cotton growth and yield during both seasons, although yield reduction in shaded (9 days) cotton was significant only in 2013-14. Under individual stresses, both WL and shaded plants had similar reductions in lint yield (15% and 18%, respectively), compared with controls (non-waterlogged, non-shaded). The interactive effect of WL and shade was significant only when the effect of WL alone on cotton yield was relatively small, suggesting that shade exacerbated moderate WL but intense WL acted on yield independently of light levels. Yield reductions were the result of lower number of final bolls produced, while boll weight remained unaffected. Increased post-waterlogging fruit abscission of WL and / or shaded cotton restricted the total number of bolls produced. In addition, these stresses (individual or combined) significantly impaired leaf nitrogen acquisition, photosynthesis and the consequent development of new fruiting nodes

Cambodian rice farmers’ knowledge, attitudes, and practices (KAPs) regarding insect pest management and pesticide use

Insect pests are a serious problem for rice farmers in Cambodia, threatening livelihoods and food security. To protect their yields, farmers are dependent on broad-spectrum pesticides, which has led to a pesticide ‘lock-in’ scenario. Our study aimed to better understand farmers’ current pest management practices and the underlying knowledge and attitudes driving these behaviours. We surveyed rice farming households (n = 168) from five different villages in Battambang Province, Cambodia. Survey respondents considered insect pests to be the most significant cause of yield loss. Respondents depended solely on chemical insecticides to manage insect pests. Combinations of agronomic and pesticide application practices contributed to pesticide dependency, including high seeding rate, insecticide timing and application rate. Additionally, 77% of respondents misidentified the beneficial lady beetle, Micraspis discolor, as a pest. Respondents indicated a desire for education and training on pest and beneficial arthropod identification, safe pesticide use, and improved cropping practices. We suggest critical areas for education and training are damage thresholds of local pests, the role of natural enemies, and improved awareness of pesticide toxicity and exposure. Promoting local knowledge sharing to engage and empower farmers to make informed decisions about their own pest management can forge a pathway away from pesticide dependency.</p

Does the social gradient remain in the dietary habits of a health-conscious population? A study of Seventh-Day Adventists in West Malaysia

Background: Socioeconomic status (SES) is a strong predictor of health, and individuals with higher SES generally have better health than those with lower SES. One of the pathways that SES influences health is through health behaviors, such as dietary intake, and a higher SES has been associated with a better diet. The purpose of this study was to determine whether there was a social gradient in dietary habits among the Seventh-Day Adventists, a group of conservative Christians, where healthy eating is part of the doctrinal teaching. Methods: Data from a survey of 574 Adventists residing in West Malaysia, aged 18–80 years, were analyzed. Dietary habits were measured using the Nutrition subscale of Health Promoting Lifestyle Profile II. Results: Education and income were significantly associated with dietary habits before and after controlling for demographics. There was a gradient of association; a higher level of education and higher income were associated with better dietary habits. However, only education remained significantly associated with dietary habits when the other two socioeconomic variables were included. Employment was not significantly associated with dietary habits before or after controlling for demographic variables and the other two sociodemographic variables. Conclusions: This study showed that education is the strongest predictor of healthy diet, and a social gradient in dietary habits still exists even among health-conscious population

Effects of elevated CO 2

Changes in temperature and CO2 under the scenarios of climate change present a challenge to crop production and may have significant impacts on the yield of cotton (Gossypium hirsutum L.) crops. The aims of this study were to (a) investigate the use of novel chambers to evaluate the impacts of climate change, specifically warmer temperatures combined with elevated atmospheric CO2 concentration ([CO2]), on field-grown plants; (b) compare the combined effects of elevated [CO2] and temperature on leaf-level photosynthetic rate and plant biomass; and (c) assess the effects of elevated [CO2] and warmer temperature on soil water content and leaf-level water-use efficiency (Asat/E). Canopy evapotranspiration and assimilation (CETA) chambers were used to elevate [CO2] in the field over two consecutive seasons, but also generated higher air temperatures (on average 2–4 °C warmer) at ambient (CA: 400 μl L−1) and elevated [CO2] (CE: 650 μl L−1) from ∼44 days after planting (DAP) until 72 DAP. Elevated [CO2] increased early stage vegetative biomass by 34–68% in well-watered, field-grown cotton growing at warmer temperatures. Despite increased Asat/E with CE, there were minimal changes in leaf-level biochemistry (estimated from gas exchange) and volumetric soil water content (VSWC) over the 28 d period, potentially the result of the combination of greater biomass and improved Asat/E. We observed increased early season crop growth of cotton grown in a changing climate; however, studies are needed to assess the effects of elevated CO2 and temperature on cotton production over a full growing season in the field