“WaterMan”: an on-farm water management game with heuristic capabilities

A modern computer-based simulation tool (WaterMan) in the form of a game for on-farm water management was developed for application in training events for farmers, students, and irrigators. The WaterMan game utilizes an interactive framework, thereby allowing the user to develop scenarios and test alternatives in a convenient, risk-free environment. It includes a comprehensive soil water and salt balance calculation algorithm. It also employs heuristic capabilities for modeling all of the important aspects of on-farm water management, and to provide quantitative performance evaluations and practical water management advice to the trainees. Random events (both favorable and unfavorable) and different strategic decisions are included in the game for more realism and to provide an appropriate level of challenge according to player performance. Thus, the ability to anticipate the player skill level, and to reply with random events appropriate to the anticipated level, is provided by the heuristic capabilities used in the software. These heuristic features were developed based on a combination of two artificial intelligence approaches: (1) a pattern recognition approach and (2) reinforcement learning based on a Markov decision processes approach, specifically the Q-learning method. These two approaches were combined in a new way to account for the difference in the effect of actions taken by the player and action taken by the system in the game world. The reward function for the Q-learning method was modified to reflect the suggested classification of the WaterMan game as what is referred to as a partially competitive and partially cooperative game.     

Water uses and productivity of irrigation systems

Reducing overall water diversions for agriculture, while maintaining or increasing production to keep up with increasing world population, has been and will continue to be a challenge. Yet there is not good agreement regarding the programs needed to improve the productivity of agricultural water use, nor what increases are feasible. It is recognized that field irrigation is inherently nonuniform. So also is the distribution of water to users and water delivery service nonuniform. Here, we suggest that crop-scale irrigation uniformity can be examined at a project scale by understanding how field, farm and project irrigation systems contribute to nonuniformity. We also discuss the interrelation between project scale uniformity and the relative irrigation water supply, and their combined impact on project productivity. We provide an example which relates internal measures of project performance (e.g., water distribution operations) and external measures of project performance (e.g., project-wise water productivity).     

Boron Induced Oxidative Stress,Antioxidant Defence Response and Changes in Artemisinin Content in Artemisia annua L.

Boron is an essential plant micronutrient and the range between deficient and toxic levels of boron is narrow for most of the plants. Like other elements, boron becomes toxic to growth at high concentrations. High boron concentrations in soil reduce crop productivity in many areas of the world. The effect of increasing levels of boron (0, 0.50, 1.00, 1.50, 2.00 mm ) on oxidative stress, antioxidant defence response and changes in artemisinin content in Artemisia annua were investigated in the present study. Boron toxicity reduced the growth parameters viz. stem height, fresh weight and dry weight. Treatments induced oxidative stress resulting in lower net photosynthetic rate, stomatal conductance, internal CO₂ and total chlorophyll content. The increased activities of antioxidant enzymes like CAT, POX and SOD were also noted in response to increasing levels of boron stress. However, H₂O₂ and artemisinin content were found to be high up to 1.00 mm concentration of boron compared to control, and on applying higher doses, further reduced contents were obtained. Thus, the results suggest that a mild stress of boron can be utilized for enhanced artemisinin production.     

The significance of VA-Mycorrhiza to future arable farming in the Netherlands

Present conditions of high inputs and narrow rotations render the importance of vesicular-arbuscular mycorrhiza (VAM) in arable farming in the Netherlands rather low. Changes expected in the near future under the influence of economic pressures and environmental problems may change this situation. This is discussed in the light of some such expected changes in Dutch arable farming.     

Molecular breeding for virus resistant potato plants

To engineer resistance against potato virus X (PVX), the viral coat protein (CP) gene has been introduced into two potato cultivars. Stable expression of the gene in transgenic clones throughout the growing season has been obtained and resulted in considerably increased virus resistance. With varying frequencies depending on the original cultivar used, true-to-type PVX resistant transgenic clones have been obtained. Since deviant light sprout characteristics were invariably associated with aberrations in plant phenotype, they can be used in procedures to early screen for deviations. Furthermore, it has been possible to unequivocally discriminate between the original untransformed and independent transgenic cultivars. Although no relation has been found between the presence, if any, of the CP of potato virus Y (PVY) or potato leafroll virus (PLRV) in CP gene transgenic potato, appreciable levels of resistance to these viruses has been obtained. This suggests that the mechanism by which a viral CP gene in the potato genome evokes resistance, differs amongst various viruses.     

Progress in aphid forecasting systems

Potato virus Y and many other viruses of potatoes cause major economic losses to seed potato production in many countries. Potato virus Y, which is transmitted in a non-persistent manner, is one of the most important virus diseases of potatoes in many countries in Europe and especially in the northern regions.During the last decade there has been an increasing interest in developing methods for potato virus forecasting. The abundance of virus vectors is often estimated by yellow water traps (YWT), suction traps or field surveys. In Sweden the relationship between occurrence of alate aphids and the proportion of PVY infected progeny tubers has been studied since 1975. A dynamic simulation model for PVY has been designed for predicting the incidence of PVY. The simulation model describes a system which includes e.g., healthy and PVY diseased potato plants, different aphid species as virus vectors an their efficiency as virus vectors, the susceptibility of the potato crop according to mature plant resistance and date of haulm destruction. There was a good correlation between model output and samples of progeny tubers tested for PVY.     

Alarm pheromones and allelochemics as a means of aphid control

The relevance of studies on aphid-plant relationships for plant virus epidemiology is highlighted. Many behavior-modulating chemicals (semiochemicals) play a major role in intraspecific (pheromones) or interspecific (allelochemics) interrelations and therefore offer opportunities to interfere with virus transmission. Present knowledge on the role of semiochemicals in different behavioral events is emphasized using examples (alarm and sex pheromones, allelochemics involved in host selection, antifeedants) and their potential for controlling virus transmission and spread is discussed.