Growth, water relations and physiological processes of starfruit (Averrhoa carambola L) plants under root growth restriction

Starfruit (Averrhoa carambola L., Clone B17) plants were grown in two levels of root zone volume (3.36 m3 or 0.68 m3) and two levels of water availability (well watered or 30% of field capacity). Root restriction inhibited the growth of starfruit plants as indicated by the reduction in leaf and root growth, and to a greater extent under water stress conditions. Under well-watered conditions, root growth restriction resulted in a slight reduction in leaf water potential. Regardless of watering regimes, root growth restriction causes an increase in leaf diffusive resistance, which consequently contributes to the reduction in leaf photosynthetic rate. The beneficial effect of root growth restriction in plants grown under well watered conditions is to hasten flower initiation

Effect of irradiance on growth, physiological processes and yield of melon (Cucumis mela) plants grown in hydroponics

The effect of different irradiance levels on melon (Cucumis mela) cv. Birdie, Charity Ball and Jade Dew grown in hydroponics was investigated. Plants were exposed to mean daily irradiance levels of 11.4,8.2, 6.1 and 3.0 MJ m-2 day-1 achieved by using different levels of shade. The dry matteryield appeared to be directly proportional to the irradiance level received by plants. Stomatal conductance and photosynthetic rate were highest when the plants were grown under the highest irradiance level. Plants grown under 11.4 MJ m-2aI had the highest fruit fresh weight and total soluble solids. All cultivars failed to fruit when grown under irradiance of 3.0 MJ m-2aI

Effects of low irradiance on growth, water uptake and yield of tomatoes grown by the nutrient film technique

A study was carried out on the effects of irradiance on growth and development of tomatoes grown using the Nutrient Film Technique(NFr). Plants were exposed to mean daily irradiance levels of 14. 7, 8.5, 3.3 and 0.87 MJ m-2day-l achieved by using different levels of shade. High irradiance (14.7 and 8.5 MJ m-2day-1) increased leaf area and dry weight, root and stem dry weight compared to the plants grown under lower irradiance. Plants under shade were up to 5 DC cooler than those under high irradiance. Plant water uptake and leaf nutrient concentrations in the leaves were generally lower in shaded plants than those in full sun. The highest fruit production was obtained with an irradiance of 14. 7 MJ m-2 day-l. Plants grown under 3.3 and 0.87 MJ m-2 day-J failed to fruit

Growth and physiological changes of Averrhoa carambola as influenced by water availability

Utilizing an integrated soil moisture stress approach, two different experiments were conducted simultaneously to investigate the effects of water stress o.n growth and related physiological characteristics of Averrhoa carambola. The first experiment clearly indicated a high correlation between soil water availability and a reduction in plant vegetative growth. In the second experiment, there was a significant correlation between leaf water potential and a reduction in stomata conductance, transpiration rate and photosynthesis rate. The inhibition of photosynthesis mte was only apparent when leaf water potential was reduced to -0.85 MFa. However, chlorophyll content was only affected by a further reduction in water availability. The Telationship between physiological characteristics and vegetative growth is discussed

Deterministic model approaches in identifying and quantifying technological challenges in rice production and research and in predicting population, rice production and consumption in Malaysia

In general, rice production and sufficiency is the main concern to all Asian countries in currently facing the ever growing population and climatic uncertainties. The consumption in Malaysia relies largely on the locally produced (70%) and imported (30%) rice for years. The price hike of this staple food, which can be categorized as a security food crop with an annual production of 1.6 million tons (beras) yielded from about 650,000 ha of the harvested paddy irrigated- and non-irrigated growing areas nationwide, could possibly be expensive to the lower-income consumers. With “no further reduction” in the modelled per capita rice consumption (82.3 kg/person/ year) versus the increasing population, various efforts must be made in term of research and technological advancement, increased cropping hectarage, as well as active extension program to increase the production of rice for consumption, self-sufficiency and more importantly, for having strong rice stock-file accumulation. Based on the data gathered from the past 27-years (1980 – 2007), the deterministic mathematical models of the Malaysian population, rice per capita consumption and five rice yield models versus years (1980 – 2007 and 2008 – 2030) were developed and predicted. The proposed model was based on the national average yields over the years and the model could be used to predict the yield ‘close’ to the nation’s rice production in the years ahead. The data on the crop cutting test or survey were used for comparison purposes. With the derivatives of the yield models, the quantitative technological advancement indexes were used in identifying the research objective, scope and areas, as well as in quantifying the contribution of crops and their management-related technologies in the past, present and predicted technological performances in rice production. To reach sufficient rice production at a relatively faster rate, the scope of the research’s objective should be based on the high yield model, in which the averaged yield could reach 13.4 t/ha in the year 2030. The priority order of the research areas would be irrigation/water > crop establishment-related management > sustainability of the existing management technology > large plot production-related adaptive studies (technological uniformity studies) > continual varietal improvement. The local released varieties are ecologically suited to the Malaysian rice growing areas, where varietal development and improvement are generally time consuming. With the current planted hectareage, coupled with the inclusion of the planned additional 100,000 ha (assumed to be staggered), as planned by the Ministry of Agriculture and with the conversion of the non-fully to fully irrigated areas by 2012, the Malaysian rice self-sufficiency is predicted to be observed/achieved in 2012. The ‘modified higher-order polynomial’ yield model which was conditioned with the scope of the above research objective and the area priorities predicts the rice production of 2.0, 4.4 and 9.1 million t/ha in 2010, 2020 and 2030, respectively. With the modelled minimum per capita consumption (82.3 g/person/year) and the predicted population of 29.3 (2010), 36.7 (2020) and 45.7 million (2030), the respective consumption, surplus and self-sufficiency would be 2.4, 3.0 and 3.8 million tons, -0.4, 1.3 and 5.3 million tons and 83, 144 and 241%, respectively. The surplus could then be used for the stock-pile accumulation and export

Effects of Partial Rootzone and Controlled Deficit Irrigation on Growth, Yield and Peroxidase Activities of Tomatoes (Lycopersicon esculentum Mill.)

The aim of the experiment was to examine the application of partial rootzone drying and deficit irrigation on growth and plant development of tomatoes. Potted fresh market tomatoes (Lycopersicon esculentum Mill.) in pots were subjected to partial root zone drying (PRD) and controlled deficit irrigation (CDI) under glasshouse conditions. Roots of plants were remained attached to plants and half the volume divided in one plant and the other half planted in the other adjacent pot. The treatments were: well-watered continually maintained close to field capacity in both pots (control), CDI50 (half the amount of water in control divided equally to both pots with each watering), PRD50 (half the amount of water in control applied to one pot while water was withheld from the other pot until soil water declined to 50-70% the field capacity and then water was applied to the other pot), PRD25 (half the amount of water in control was applied to one pot while water was withheld from the other pots until soil moisture declined to 25-50% field capacity and then water was applied to the other pot) and CDI25 (quarter amount of water in control divided equally to both pots with each watering). Imposing water deficit reduced fruit yield up to 18% in PRD50 and 33% in CDI50 which coincided with an impairment of fruit expansion. The percentage of fruit dry matter and osmotic potential increased in both PRD and CDI compared with the control. The incidence of blossom end rot increased in both CDI and PRD25 compared with the control and PRD50 treatments. Cell wall peroxidase in the epidermal layer of fruit may have a role in cessation of fruit expansion towards fruit maturity under reduced water availability