Stochastic dynamic simulation of fruit abortion: a case study of sweet pepper

Abortion of reproductive organs diminishes yields in many crops. In indeterminate greenhouse crops, alternating periods of fruit abortion and fruit set exist, resulting in fluctuations in fruit yield. Factors affecting the level of abortion are e.g., the supply and demand for assimilates (source and sink strength, respectively), temperature and cultivar. However, simulation of fruit abortion is still a weak part of crop simulation models. Variation in fruit abortion exists between plants, which results in differences in the timing and the number of set fruits. Therefore, simulating fruit abortion with variation could give more realistic simulation results. The probability of a fruit to abort should be related to factors like source strength and sink strength. The more favourable the circumstances are for fruit abortion, e.g., low source strength or high sink strength, the more likely it is that the fruit aborts. Survival analysis estimates parameters quantifying the influence of explanatory variables on the abortion rate. Time-varying explanatory variables can be used in the analysis. In a case study, we used survival analysis to analyse a data set with observations on flowering, fruit abortion and fruit harvest for sweet pepper. Source and sink strength were used as explanatory variables. The resulting equation determining the probability of abortion per day was implemented in a simple simulation model to simulate fruit set. The model output, as an average of 100 plants, showed similar timing in the fluctuations in fruit set as the observations, although the amplitude of the fluctuations was in some cases underestimated. The percentage fruit set was simulated correctl

Cuckoo Search via Levy Flights

In this paper, we intend to formulate a new metaheuristic algorithm, called Cuckoo Search (CS), for solving optimization problems. This algorithm is based on the obligate brood parasitic behaviour of some cuckoo species in combination with the Levy flight behaviour of some birds and fruit flies. We validate the proposed algorithm against test functions and then compare its performance with those of genetic algorithms and particle swarm optimization. Finally, we discuss the implication of the results and suggestion for further research

Private Standards, Handling and Hygiene in Fruit Export Supply Chains: A Preliminary Evaluation of the Economic Impact of Parallel Standards

With the emergence of private food safety and quality standards in developed countries fruit exporting countries in the developing world face increasing constraints to access markets in the rich industrialised countries in the North. Producers in the South have no alternative as to make the necessary investments on farms and in pack houses to comply with the requirements of these food quality and safety standards. The export of fresh fruit is an important component of South African agricultural exports, with citrus fruit exported to markets such as Europe being of particular importance. This paper reports selected results from a large research project into the impact of private standard compliance on the quality of the fruit and the returns to farmers. The research process involved a multi-disciplinary analysis of Agricultural Economics and Microbiology / Plant pathology as we analysed the dynamics of the citrus export supply chain from the farms in South Africa to the end consumer in Europe. Sampled fruit containers were followed through the whole supply chain which allowed us to provide an exposé of the behaviour of the different actors in the citrus supply chain and obtain some evidence of poor handling and hygiene standards by means of a comparison of the experimental observations with various relevant components of the EurepGAP control points and compliance criteria for fruit and vegetables. Observations suggest that these standards are adequately applied to the production and handling of fruit at the farm and pack house levels while on the other hand the subsequent stages (mainly after the importing harbour in Europe) of the fruit supply chain are seemingly not subjected to the same strict requirements laid out for producers, leading to fruit quality deterioration and financial losses for producers. This constitutes clear parallel standards in terms of fruit safety and quality standards between upstream and downstream sections of the supply chain and questions thus the purpose of the standards and the financial return for producers making large investments to comply with these privately introduced standards.International Relations/Trade,

Flower heating following anthesis and the evolution of gall midge pollination in Schisandraceae

Premise of the study: Flower heating is known from a few species in 11 of the c. 450 families of flowering plants. Flowers in these families produce heat metabolically and are adapted to beetles or flies as pollinators. Here, we focus on the Schisandraceae, an American/Asian plant family known to exhibit flower heating in some species, but not others, raising the question of the adaptive function of heat production. Methods: We used field observations, experiments, and ancestral trait reconstruction on a molecular phylogeny for Schisandraceae that includes the investigated species. Key results: At least two Chinese species of Illicium are exclusively pollinated by gall midges that use the flowers as brood sites (not for pollen feeding). Continuous monitoring of flower temperatures revealed that the highest temperatures were attained after the flowers’ sexual functions were over, and experiments showed that post-anthetic warming benefited larval development, not fruit development. Midge larvae in flowers with trimmed tepals (and hence a lower temperature) died, but fruit set ratios remained unchanged. Based on the DNA phylogeny, gall midge pollination evolved from general fly/beetle pollination several times in Schisandraceae, with some species adapted to flower-breeding midges, others to pollen-feeding midges. Conclusions: Flower heating may be an ancestral trait in Schisandraceae that became co-opted in species pollinated by flower-breeding midges requiring long-persistent warm chambers for larval development

Dietry and lifestyle changes of Malaysia breast cancer survivors: a qualitative study

Objective : This study was performed to determine changes in diet and lifestyle among breast cancer survivors in Malaysia. Methods : This was a qualitative study done on fifteen survivors (8 Malays and 7 non-Malays) obtained from the Oncology and Surgery Department, National University of Malaysia Hospital. The study was conducted using a semi-structured interview format. The data obtained were sorted into various categories via content analysis. Results : Majority of breast cancer survivors increased their fruit and vegetable intake following diagnosis. Some non-Malays changed to vegetarian whereas all the Malays remained on the same dietary pattern. As far as exercise was concerned, all Malays did not exercise before diagnosis, but did so after diagnosis, whereas most of non-Malays did not exercise either before or after diagnosis. Conclusion : Some changes were noticed in dietary and lifestyle behaviors after diagnosis among some survivors. The differences were due to their different cultural and religious backgrounds