Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Factors affecting fertilizer use efficiency in dry season paddy production in Makawanpur district, mid hill, Nepal  [PDF]
M Thapa
Agronomy Journal of Nepal , 2010, DOI: 10.3126/ajn.v1i0.7552
Abstract: On-farm assessment of factors defining fertilizer use efficiency (FUE) for dry season paddy production was carried out through field survey and applying a two-step approach. The research was carried out in Makawanpur district, central mid hill, Nepal for the early rice ( Chaite season) cropping season 2000. Data on land and land use aspects and yield record were collected through interview and field observation. Data entry, coding and normalization procedure were followed by stepwise regression analysis. In step one, the general regression model for causes of actual yield variations was derived; it included some land and management parameters that satisfactorily explained the variability of actual yields (adjusted R 2 of 65 %). This model was used to calculate the adjusted yields by removing the impacts of non-fertilizer related variables from the actual yield data. In order to evaluate aspects of fertilizer use efficiency (step two), a stepwise regression produced a highly significant (adjusted R2 of 45%) result. The important factors defining FUE were the relationship between many parameters such as quantity of 1st N topdressing x soil pH, basal N x FYM, 1st N top dressing x good drainage condition, 2nd N top dressing x insect attack during tillering-flowering stage, 2nd N topdressing x soil pH, basal N x soil pH, FYM x soil pH, 1st N topdressing x FYM and 2nd N topdressing x zinc deficiency. Thus the study concluded that FUE is one of the critical issues that hindered sustainable paddy production. The timing and quantity of fertilizer especially N application, source of fertilizer, nutrient content combination, and their interactions with land and land use aspects were crucial elements for getting optimum response to fertilizer. DOI: http://dx.doi.org/10.3126/ajn.v1i0.7552 Agronomy Journal of Nepal (Agron JN) Vol. 1: 2010 pp.123-133
Reconstruction of the Rainfall in Rainy Season Based on Historical Drought/ Flood Grades
Reconstruction of the Rainfall in Rainy Season Based on Historical Drought/Flood Grades

Xiong Anyuan,Wu Yijin,Cai Shuming,
Xiong Anyuan
,Wu Yijin,Cai Shuming

大气科学进展 , 1999,
Abstract: On the basis of historical yearly drought and flood grades from A. D. 1470 to A. D. 1949, the ten-year mean precipitation in the rainy season in Wuhan district was reconstructed by means of statistical method. The reconstructing method was testified to be simple and effective.
Insight into Differential Responses of Upland and Paddy Rice to Drought Stress by Comparative Expression Profiling Analysis  [PDF]
Xipeng Ding,Xiaokai Li,Lizhong Xiong
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14035214
Abstract: In this study, the drought responses of two genotypes, IRAT109 and Zhenshan 97 (ZS97), representing upland and paddy rice, respectively, were systematically compared at the morphological, physiological and transcriptional levels. IRAT109 has better performance in traits related to drought avoidance, such as leaf rolling, root volumes, the ratio of leaf water loss and relative conductivity. At the transcriptional level, more genes were induced by drought in IRAT109 at the early drought stage, but more genes had dynamic expression patterns in ZS97 at different drought degrees. Under drought conditions, more genes related to reproductive development and establishment of localization were repressed in IRAT109, but more genes involved in degradation of cellular components were induced in ZS97. By checking the expression patterns of 36 drought-responsive genes (located in 14 quantitative trail loci [QTL] intervals) in ZS97, IRAT109 and near isogenic lines (NILs) of the QTL intervals, we found that more than half of these genes had their expression patterns or expression levels changed in the NILs when compared to that in ZS97 or IRAT109. Our results may provide valuable information for dissecting the genetic bases of traits related to drought resistance, as well as for narrowing the candidate genes for the traits.
Evaluation of Deep Percolation Rates at a Transect of Paddy Fields During Crop Season  [cached]
S. M. Mousavi,A. Hoshmand,S. Bromandnasab,M. Yazdani
Journal of Science and Technology of Agriculture and Natural Resources , 2012,
Abstract: The common method of irrigating rice in paddy fields of Iran, like most countries, is flooded irrigation. The water required in this method is too much. However, because of water shortage in recent years, and malfunctioning of irrigation systems, it is needed to use water in a reasonable way and increase water use efficiency. Therefore, it is necessary to know water loss amounts at the paddy fields. The deep percolation (DP) was measured by closed- and open-bottom rings in 4 locations, and 7 sites at each location, of paddy fields in Somae-Sara city, Guilan province. These locations were selected on the base of different physiographic units. The average DP of these locations was also monitored during plant growth season. The measurements were performed twice a week. Results showed that the rate of DP varied during the season, and could take a positive or negative value. The most important factors of these variations were the lateral seepage (from surrounding rice fields) and the high perched groundwater table in paddy fields.
Impacts of Drought on Socio-Economic Conditions of Paddy Farmers in Guilan Province, North of Iran
Hamid Devisti,Mohamad Karim Moetamed
International Journal of Agricultural Management and Development , 2011,
Abstract: The purpose of this study was to survey impacts of droughton Socio-economic conditions of Guilan Paddy farmers.Besides recognizing these impacts, it ranked them accordingto the viewpoint of the Paddy farmers. It was of the descriptive-correlation type. Questionnaire was the main tool of thisstudy. To determine the validity of questionnaire used of commentsof panel experts and reliability of the questionnaire byusing of Cronbach's alpha coefficient was 89%. The informationgathered by using the survey method. The statistical populationwas the farmers whom their basic career was production ofrice and according to the information of Agricultural Organization(Jihad-e-Keshavarzi) in 2009 was caught by drought. By usingthe proportional stratified sample method, 270 of theseindividuals were chosen and filled in the questionnaires. Inorder to determine the scale of drought impacts, year 2008 (ayear which paddy farmers had ensured water reservoir) comparedto year 2009 (a year which paddy farmers were caught bydrought and water shortage). The results indicated that droughtcaused decrease in white-rice production for 312 kg per hectare.This problem also caused increase in costs, decrease in income,decrease in saved money, and increase in anxiety, mentalproblems etc on Guilan paddy farmers. Other findings indicatedthat there hasn’t been statistically significant relationshipbetween age and farming experience of paddy farmers withthe amount of damage. But, there was statistically significantrelationship between literacy, type of water resource and takingextension advices with amount of damage.
Organic and Inorganic Carbon in Paddy Soil as Evaluated by Mid-Infrared Photoacoustic Spectroscopy  [PDF]
Du Changwen, Zhou Jianmin, Keith W. Goyne
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043368
Abstract: Paddy soils are classified as wetlands which play a vital role in climatic change and food production. Soil carbon (C), especially soil organic C (SOC), in paddy soils has been received considerable attention as of recent. However, considerably less attention has been given to soil inorganic carbon (SIC) in paddy soils and the relationship between SOC and SIC at interface between soil and the atmosphere. The objective of this research was to investigate the utility of applying Fourier transform mid-infrared photoacoustic spectroscopy (FTIR-PAS) to explore SOC and SIC present near the surface (0–10 μm) of paddy soils. The FTIR-PAS spectra revealed an unique absorption region in the wavenumber range of 1,350–1,500 cm?1 that was dominated by C-O (carbonate) and C-H bending vibrations (organic materials), and these vibrations were used to represented SIC and SOC, respectively. A circular distribution between SIC and SOC on the surface of paddy soils was determined using principal component analysis (PCA), and the distribution showed no significant relationship with the age of paddy soil. However, SIC and SOC were negatively correlated, and higher SIC content was observed near the soil surface. This relationship suggests that SIC in soil surface plays important roles in the soil C dynamics.
Assessment of remotely sensed drought features in vulnerable agriculture
N. R. Dalezios, A. Blanta,N. V. Spyropoulos
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2012,
Abstract: The growing number and effectiveness of Earth observation satellite systems, along with the increasing reliability of remote sensing methodologies and techniques, present a wide range of new capabilities in monitoring and assessing droughts. A number of drought indices have been developed based on NOAA-AVHRR data exploiting the remote sensing potential at different temporal scales. In this paper, the remotely sensed Reconnaissance Drought Index (RDI) is employed for the quantification of drought. RDI enables the assessment of hydro-meteorological drought, since it uses hydrometeorological parameters, such as precipitation and potential evapotranspiration. The study area is Thessaly, central Greece, which is a drought-prone agricultural region characterized by vulnerable agriculture. Several drought features are analyzed and assessed by using monthly RDI images over the period 1981–2001: severity, areal extent, duration, periodicity, onset and end time. The results show an increase in the areal extent during each drought episode and that droughts are classified into two classes, namely small areal extent drought and large areal extent drought, respectively, lasting 12 or 13 months coinciding closely with the hydrological year. The onset of large droughts coincides with the beginning of the hydrological year, whereas the onset of small droughts is in spring. During each drought episode, the maximum occurs usually in the summer and they all last until the end of the hydrological year. This finding could justify an empirical prognostic potential of drought assessment.
Assessment of a GOES microburst product for two early cold season convective storms  [PDF]
Kenneth L. Pryor
Physics , 2010,
Abstract: This paper presents an assessment of the new Geostationary Operational Environmental Satellite (GOES) imager channel 3 - 4 brightness temperature difference (BTD) product for two early cold season severe convective storm events that occurred over the Mid-Atlantic region on 17 November and 1 December 2010. Both of these events involved squall lines that produced strong downbursts as they tracked over the Tidal Potomac River and Chesapeake Bay regions. It has been found recently that the BTD between GOES infrared channel 3 (water vapor) and channel 4 (thermal infrared) can highlight regions where severe outflow wind generation (i.e. downbursts, microbursts) is likely due to the channeling of dry mid-tropospheric air into the precipitation core of a deep, moist convective storm. These two cases demonstrate effective operational use of this image product for cold-season convective storm events.
Relationship of late-season ear leaf nitrogen with early- to mid-season plant height of corn  [PDF]
Xinhua Yin, M. Angela McClure, Robert M. Hayes
Agricultural Sciences (AS) , 2012, DOI: 10.4236/as.2012.32035
Abstract: Nitrogen concentration in the ear leaf is a good indicator of corn (Zea mays L.) N nutrition status during late growing season. This study was done to examine the relationship of late-season ear leaf N concentration with early- to mid- season plant height of corn at Milan, TN from 2008 to 2010 using linear, quadratic, square root, logarithmic, and exponential models. Six N rate treatments (0, 62, 123, 185, 247, and 308 kg·N·ha-1) repeated four times were implemented each year in a randomized complete block design under four major cropping systems: corn after corn, corn after soybean [Glycine max (L.) Merr.], corn after cotton [Gossypium hirsutum (L.)], and irrigated corn after soybean. The relationship of ear leaf N concentration determined at the blister growth stage (R2) with plant height measured at the 6-leaf (V6), 10-leaf (V10), and 12-leaf (V12) growth stages was statistically significant and positive in non-irrigated corn under normal weather conditions. However, the strength of this relationship was weak to moderate with the determination coefficient (R2) values ranging from 0.21 to 0.51. This relationship was generally improved as the growing season progressed from V6 to V12. Irrigation and abnormal weather seemed to have adverse effects on this relationship. The five regression models performed similarly in the evaluation of this relationship regardless of growth stage, year, and cropping system. Our results suggest that unlike the relationship of corn yield at harvest with plant height measured during early- to mid-season or the relationship of leaf N concentration with plant height when both are measured simultaneously during early- to mid-season, the relationship of late-season ear leaf N concentration with early- to mid-season plant height may not be strong enough to be used to develop algorithms for variable-rate N applications on corn within a field no matter which regression model is used to describe this relationship.
Risk Assessment on Drought Disaster in China Based on Integrative Cloud Model  [cached]
Junfei Chen,Shufang Zhao,Quanxi Shao,Huimin Wang
Research Journal of Applied Sciences, Engineering and Technology , 2012,
Abstract: This study promotes cloud model for risk assessment of drought disaster. Cloud model is an effective tool in uncertain transforming between qualitative concepts and their quantitative expressions. Cloud is expressed by a concept with three quantitative characteristics of expectation, entropy and hyper entropy and the mapping between qualitative and quantitative is realized. In this study, considering the fuzziness and uncertainty of drought disaster, we established the comprehensive cloudy model based on entropy weight method for evaluating the risk of drought disaster. The disaster-affected rate and disaster-damaged rate are selected as the evaluation indices of drought degree. The model is applied to assess the drought disaster risk in China. The BP neural network, hard division method and integrative cloud model are compared, and the integrative cloud model is shown better for evaluating drought risk. This study shows that risk assessment of drought disaster based on cloud model is feasible and effective and can provide decision-making for the risk assessment of drought disaster.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.