This paper describes a study of the use of large diameter "agrowells" used for irrigation in Sri Lanka. Detailed field information for a single location is presented and a numerical radial flow model was used to interpret the field response. Initially the model was used to represent a pumping test in which the pumping and subsequent recovery were monitored. It was then used to investigate the operation of the well during a dry season. Satisfactory agreement could only be obtained when account was taken of the withdrawal of water from below the water table by trees. From the simulation it was possible to show that skilful farming practice could be used in steadily exploiting the resources for irrigation over the whole of the dry season. Interprétation par un modèle d'écoulement radial du comportement d'un système de puits agricoles au Sri-Lanka Résumé Cet article est une étude de l'utilisation des "agropuits" au Sri Lanka; ceux-ci sont des puits de grand diamètre utilisés pour l'irrigation. Nous avons présenté les caractéristiques détaillées d'un puits particulier et nous avons utilisé un modèle numérique d'écoulement radial pour étudier son comportement . Le modèle a d'abord été utilisé pour interpréter un essai de débit au cours duquel le niveau de l'eau dans le puits a été mesuré pendant et après l'arrêt du pompage jusqu'au retour à l'équilibre. Le modèle a ensuite été utilisé pour évaluer la performance du puits pendant une saison sèche. Des résultats satisfaisants ne peuvent être obtenus que si l'on tient compte de la capacité des arbres à prélever de l'eau au-dessous du niveau de la nappe. Il a été possible grâce à la simulation de montrer qu'un bonne pratique agricole consiste à exploiter la ressource de façon continue pendant toute la durée de la saison sèche.

Drought stress is one of the most adverse limitations of local black pepper production in Dry and Intermediate zones of Sri Lanka. Application of Super Absorbent Polymers (SAPs) is hypothesized to result in the optimised use of water resources in these regions. A study was undertaken to examine the effect of different levels of irrigation intervals and different level of SAPs and then to find out the best treatment combination for growth of black pepper plants under nursery management. The experiment was conducted at Intercropping and Betel Research Station, Narammala. GK49 was the selected variety and Zeba (commercial name) was the selected SAP type. The experiment was carried out following a factorial layout based on Complete Random Design (CRD) with three replicates. The factors were three levels of irrigation intervals as 4, 8 and 10 days (T1 to T3) and four levels of SAPs as no Zeba, 1g, 1.5g and 2g of Zeba (L1 to L4). Plant growth parameters were measured at two weeks interval and all the parameters were analysed by anova using SAS software. Statistical analysis had shown that there were

Understanding the effect of temperature stress on growth and yield of crops, and also identifying suitable management options to sustain the productivity under different changes in the natural environment are of timely importance. The main aim of this research is to compare the growth, yield and quality parameters of Tomato (solanum lycopersicum) variety Thilina grown with mulch when subjected to temperature and water stress if there is global warming. The plants were grown in pots under temperature-controlled poly tunnels. Main plot included two different irrigation applications (no water stress by irrigation to field capacity moisture level and, water stress by irrigating only up to the 50% of the available water capacity). Coir dust and saw dust were used as mulch and sub plots contained 3 different temperature regimes (34°C maximum temperature poly tunnel/32°C maximum temperature polytunnel/Open space-ambient temperature). The treatments were set up in a completely randomized design with 3 replicates. To make sure of the temperature replication, the trials were repeated 3 times. According to the results, there is significant effect of mulch on growth parameters of Tomato plants exposed to water and temperature stresses. Individual water stress showed a highly significant effect on growth, and yield parameters of Tomato. High yield reduction was shown in the high temperature (34°C) and water stressed plants. Mulching of saw dust and coir dust improved the yield even at 34 °C temperature treatment. Therefore, Tomato variety Thilina would not be a successful crop in open field condition due to temperature and water stress if there is global warming, but mulching will help to improve the situation.

The effect of climate change on global food security has assumed a frightening dimension in developing nations. The need for efficient management to cope with the effect of climate change became imperative. The main aim of this research is to compare the growth and yield parameters of Chilli when it subjected to temperature and water stress. Experiments were conducted on the growing seasons of 2010 and 2011 at the Open University Sri Lanka Agricultural field located at Nawala, Nugegoda using Chilli Varity MI-2 in temperature regulated polytunnels. Split plot experiment based on Completely Randomized Design with 10 replicates was applied as an experimental design. Main plot included two different wetting applications (No water stress-at field capacity level and water stress at 50 % depletion from the field capacity level) and sub plots contained 3 different temperature regimes (34 °C, 32 °C temperature and ambient temperature).According to the results the temperature stress has especially affected the plant height, branches, canopy diameter and number of fruit weight at 0.01 probability levels. Further temperature stress showed significant effect at 0.05 probability level on transplant success, fruit diameter and number of fruits per plant. According to the yield parameters it was observed that interaction effect of the stresses of temperature and water had higher significant impact on growth and yield of Chilli. Yield reduction of Chilli due to temperature stress can be overcome by providing water at field capacity level of the soil moisture during growing period.

Experiments were conducted in the temperature regulated polytunnels for five consecutive growing seasons at the Open University of Sri Lanka to evaluate the impact of the enhanced temperature and water stress due to Global warming on marketable fruit quality. Split plot experiment based on complete randomized design with 10 replicates was applied as experimental design. The plants were grown in pots, and the main plot included two moisture levels (No water stress, 50% water stress from the field capacity) and sub plots contained 3 different temperature regimes (34°C maximum temperature / 32°C maximum temperature / ambient temperature). Experiments were repeated for 3 seasons to replicate temperature effect. The combination effect of water stress and temperature stress proved to be a significant drawback for tomato yield and marketable fruit quality such as colour, shape, soluble solids content, pH and sugar acid ratio. Mealy bug attack too was very significant in high temperature poly tunnel experiment which affected the marketable fruit quality. Therefore, tomato variety Rajitha could not be a successful open field crop in the dry zone of Sri Lanka if temperature is increased due to global warming. But tomato could be cultivated under green houses by providing adequate water and required soil temperature.