Suitable inflow rate and furrow length for simplified surge flow irrigation

Paddy and Water Environment - In the arid lands covering Uzbekistan, furrow irrigation with low application efficiency is still widely used due to a lack of funds and shortage of labor. To save...     

Rice plant growth and nutrient leaching under different patterns of split chemical fertilization on sandy soil using a pot

Paddy and Water Environment - Savannakhet Province has 25% of the total lowland rice cultivation area of Lao People’s Democratic Republic (Laos). However, most of the fields are rainfed, with...     

Variation in lowland rice yield and its determinants in a rainfed area in Savannakhet Province,Laos

Paddy and Water Environment - Irrigated areas in the Lao People’s Democratic Republic (Laos) constitute only 12% of the total agricultural land. Most of the lowland rice is cultivated under...     

Factors affecting differences in the rainy season rice yield in a lowland area of a mountainous village in Lao PDR

The unevenness of rice productivity in lowland areas is caused by differences in farming techniques, accessibility of water, planting environment, and other field-specific factors. In order to increase rice production in low-productivity fields, this study examined the factors affecting yield reduction. In this study, the influence of water conditions, farming activities, and soil fertility on rice yield were analyzed in a lowland area located in the northern part of Lao PDR. A field survey was conducted in a village in Vientiane Province during the rainy season of 2013. Water conditions were observed (i) prior to land preparation, (ii) between land preparation and transplanting, and (iii) after transplanting. Farming activities were recorded in each lowland rice field weekly from June to August. Yield surveys were also conducted in 47 field blocks, and soil samples were collected for soil fertility analyses. The ponding of fields commenced in the middle of June, and extended from the upper part to the lower part of the lowland area. Transplanting was conducted following the distribution of surface water, and no serious water shortages were observed after transplanting in the surveyed areas. There was no correlation between grain yield and the content of total nitrogen or available phosphorus in the field soil. Significant differences in grain yield were detected between direct and plot-to-plot irrigation, early and late ponding, and transplanting in July and in August. The results suggest that water shortages and the delay of field ponding before land preparation led to late transplanting which caused yield reduction.     

Effect of different microbubble generation methods on growth of Japanese mustard spinach

To provide the necessary oxygen for plant growth, the effectiveness of different generating methods of microbubbles (MB), a gas-water circulation type or a pressurization type (pressurization treatment), was investigated by comparing the growth characteristics and morphological observation of Brassica campestris L. var. Komatsuna Matsum. The plant growth in the pressurization treatment were significantly less than those in the circulation treatment at 3 weeks after planting. In plants grown in the pressurization treatment, epidermal cell abrasion and plasmolysis, indicators of cell death, were observed in root tip cells at 3 weeks after planting. The growth inhibition of plant in the pressurization treatment is suggested to be related to the oxidization of Fe in the nutrient solution under super-saturated dissolved oxygen conditions, the generation of hydroxyl radicals from MB, the oxidization of the root tip cell membrane, and osmotic stress to the roots.     

Effect of jasmonates on ethylene biosynthesis and aroma volatile emission in Japanese apricot infected by a pathogen (Colletotrichum gloeosporioides)

The effects of the application of the jasmonic acid derivative n-propyl dihydrojasmonate (PDJ) on ethylene biosynthesis, volatile compounds, and endogenous jasmonic acid (JA) and methyl jasmonate (MeJA) were examined in Japanese apricot (Prunus mume Sieb.) infected by a pathogen (Colletotrichum gloeosporioides). The fruit were dipped into 0.4 mM PDJ solution before inoculation with the pathogen and stored at 25 °C for 6 days. The inoculation induced an increase in 1-aminocyclopropane-1-carboxylic acid (ACC), ethylene, JA, and MeJA. In contrast, PDJ application reduced the endogenous JA, MeJA, and ethylene production and expression of the ACC oxidase gene (PmACO1) caused by the pathogen infection. The lesion diameter with C. gloeosporioides decreased upon PDJ application. The alcohol, ester, ketone, and lactone concentrations and alcohol acyltransferase (AAT) activity increased in the pathogen-infected fruit, but were decreased by PDJ application. These results suggest that PDJ application might influence ethylene production through PmACO1 and that aroma volatile emissions affected by pathogen infection can be correlated with the ethylene production, which is mediated by the levels of jasmonates.     

Estimation of potential area of preparatory irrigation for rainy season lowland rice and supplemental irrigation for dry season cropping using existing reservoirs constructed for aquaculture: a case study in semi-mountainous village,Lao PDR

Paddy and Water Environment - The rural area in Lao PDR has a low yield of rainy season lowland rice, and most rice fields are not utilized for crop cultivation during the dry season. Delay in...     

Effect of microbubbles in deep flow hydroponic culture on Spinach growth

Microbubbled air may be efficiently supplied to the culture solution, since microbubbles are more efficiently dissolved in water than millibubbles. To establish an enhanced air supply method in the hydroponic culture of vegetables, microbubbles were applied using the deep flow technique to a hydroponic culture system of spinach. Spinach was cultivated in culture solution treated microbubbles for 21 days, then harvested and measured growth and concentrations of inorganic components and chlorophyll in the leaf blade. The results showed that microbubbles applied to the culture solution promoted the growth of spinach more than that by millibubbles. Using microbubbles, cultivars maintained a high concentration of dissolved oxygen at the middle growth stage, during which the dissolved oxygen concentration in the culture solution was reduced by the active root respiration. This result suggests that microbubbles are more effective than millibubbles in the hydroponic culture of vegetables.     

Effects of microbubble generation methods and dissolved oxygen concentrations on growth of Japanese mustard spinach in hydroponic culture

The use of microbubbles (MB) can improve the oxygen supply to plants grown under the deep flow technique of hydroponic culture. In a previous study, we compared the growth of komatsuna (Brassica rapa L. perviridis, Japanese mustard spinach) plants grown under hydroponic culture with MB generated by the pressurisation (P) method and the gas-water circulation (G) method. Plant growth was significantly lower in the presence of the P-MB than the G-MB. In this study, we aimed to identify the factor(s) responsible for the poor growth of komatsuna plants in the presence of P-MB. At three weeks after planting, the growth of the P-MB plants was less than the growth of G-MP plants and controls, regardless of dissolved oxygen concentrations. Analysis of the root tips by transmission electron microscopy showed plasmolysis of the P-MB root tip cells but not of the G-MB and control root tips. Our results suggest that the growth inhibition of plants grown in the presence of P-MB is due to inhibition of water and nutrition absorption from root tip cells due to this plasmolysis. This is likely due to oxidisation of root tip cells by hydroxyl radicals generated by many fine MB and/or osmotic stresses caused by the MB.