Basal Fertilizer Application Research Articles

Effects of Cysteine and Inorganic Sulfur Applications at Different Growth Stages on Grain Protein and End-Use Quality in Wheat.

The aim of this study was to test the significant effects of inorganic sulfur and cysteine on grain protein and flour quality in wheat and to provide a theoretical basis of wheat cultivation techniques with high yield and quality. In the field experiment, a winter wheat cultivar, Yangmai 16, was used, and five treatments were established, i.e., S0 (no sulfur fertilizer application during the whole wheat growth period), S(B)60 (60 kg ha−1 inorganic sulfur fertilizer was applied as the basal fertilizer), Cys(B)60 (60 kg ha−1 cysteine sulfur fertilizer was applied as the basal fertilizer), S(J)60 (60 kg ha−1 inorganic sulfur fertilizer was applied as the jointing fertilizer), and Cys(J)60 (60 kg ha−1 cysteine sulfur fertilizer was applied as the jointing fertilizer). The fertilizer application at jointing stage showed a better influence than basal fertilizer application on protein quality; for the content of albumin, gliadin, and high molecular weight glutenin (HMW-GS), Cys(J)60 was the best among these treatments. An increase of 7.9%, 24.4%, 43.5%, 22.7% and 36.4% was found in grain yield, glutenin content, glutenin macro-polymer (GMP), low molecular weight glutenin (LMW-GS), and S content under Cys(J)60, in relation to the control, respectively. A similar trend was found in the end-use quality, as exemplified by an increase of 38.6%, 10.9%, 60.5%, and 109.8% in wet gluten content, dry gluten content, sedimentation volume, and bread-specific volume, respectively; a decrease of 69.3% and 69.1% in bread hardness and bread chewiness was found under Cys(J)60. In terms of application period, topdressing at jointing stage is compared with base fertilizer, the sulfur fertilizer application at jointing stage showed larger effects on grain protein and flour quality, from the different types of sulfur fertilizer, the application of cysteine performed better than the use of inorganic sulfur. The Cys(J)60 exhibited the best effects on protein and flour quality. It was suggested that sufficient sulfur application at jointing stage has the potential to enhance the grain protein and flour quality.

Analysis of Ammonia Volatilization Loss from a Paddy Soil with Empirical and Mechanistic Models

AbstractAmmonia volatilization from agricultural land has a negative impact on the atmospheric, aqueous, and land environments. However, this process is still not fully understood. In this study, a 2‐year field experiment is conducted in the Taihu Lake region of China to monitor ammonia volatilization from a paddy soil. The ammonia volatilization losses are in the range of 43.4 to 53.6 kg N ha−1 in the year 2013 and 25.9 to 35.4 kg N ha−1 in the year 2014, which account for 19.7% to 19.9% and 11.8% to 13.1% of the applied nitrogen with two different N treatments (N1: 220 kg N ha−1, N2: 270 kg N ha−1). The ammonia volatilization loss is highest during the basal fertilizer application, followed by the tillering and the ear‐differentiation stages. Then, two empirical models and one mechanistic model are used to simulate the ammonia volatilization process. These models are calibrated and validated with field experimental data. The results show that none of the three models accurately predict the ammonia volatilized from the rice field (R2 < 0.40), however, among the three models evaluated, the mechanistic model is more effective in simulating the ammonia volatilization process (R2 = 0.38).

Particulate N and P exports from sugarcane growing watershed are more influenced by surface runoff than fertilization

Excessive fertilization and accelerated erosion, due to intensive agriculture, have resulted in a large nitrogen (N) and phosphorus (P) exports from farmlands to rivers and lakes, contributing substantially to eutrophication in many regions. But many studies mainly emphasized the influence of fertilizer overuse, neglecting the contribution of accelerated erosion to diffuse N and P pollution. Thus, the objectives of this study were to determine the seasonal changes of sediment and particulate N (PN) and P (PP) entering the river by surface runoff from core sugarcane growing watershed, and clarify their influencing factors. Surface runoff, sediment and associated nutrients were measured in summer and autumn at the outlets of three sub-watersheds under rainfall events, in Nala watershed, southern subtropics of China. The total sediment, PN and PP loads in the entire seasons were 30.9 t ha−1, 41.1 kg ha−1 and 14.7 kg ha−1, respectively. The seasonal exports from the entire watershed in early summer, late summer, early autumn and late autumn were respectively, 8.5, 10.5, 11.6 and 0.3 t ha−1 for sediment, 15.3, 12.4, 12.9, and 0.4 kg ha−1 for PN, and 3.4, 5.3, 5.9, and 0.1 kg ha−1 for PP. The largest sediment and PP exports in late autumn coincided with the rainfall peak (208.8 mm), but the highest PN export in early summer was due to sugarcane establishment and basal fertilizer application in the watershed. Particulate N and P exports across the seasons were equivalent to 14 % and 64 % of applied N (296.4 kg ha−1 yr−1) and P (22.8 kg ha−1 yr−1) fertilizers, respectively, but PP exports were highest when no fertilizer and 31 % of P fertilizer were applied. Surface runoff had significant positive relationships with exported sediment and particulate nutrient loads, explaining 41–72 % of the seasonal variations in sediment, PN and PP. Ground covered by sugarcane plants was inversely correlated with sediment, PN and PP exports, and explained 15–40 % of the seasonal variations. Applied N fertilizer only had a positive relationship with PN, whereas no significant relationship (P > 0.05) exists between P fertilizer and PP. The contribution of the sub-watersheds to the export of sediment and particulate nutrients only varied spatially with slope gradient. Thus, our results imply that surface runoff played a dominant role in particulate N and P exports from the sugarcane watershed, but the seasonal variations of particulate N and P exports were dependent on a combined effect of surface runoff and fertilization.

Response of Guava cv. L-49 to Urea and murate of potash fertigation levels

Farmer’s practices of guava cultivation in trend with basin irrigation and basal fertilizer application, which has low application and use efficiencies. However, some farmers in the state are reluctant to adopt drip technology, due to lack of information on fertigation scheduling and high cost of water soluble fertilizers (WSF) this practice not in vogue. Now need to assess basal fertilizer doses application through drip for better use efficiency. Guava cv. L-49 imposed to apply eleven treatment combinations comprised viz., Farmer’s practice (basin & basal application) with urea and murate of potash fertigation levels viz., Farmer’s practices (basin &basal application) (T1), drip irrigation and basal application of fertilizers (T2), 50 % RDF (N+K) at 3 days interval through fertigation(T3), 50 % RDF (N+K) at 5 days interval through fertigation(T4), 50 % RDF (N+K) at 7 days interval through fertigation(T5), 75 % RDF (N+K) at 3 days interval through fertigation(T6), 75 % RDF (N+K) at 5 days interval through fertigation(T7), 75 % RDF (N+K) at 7 days interval through fertigation(T8), 100 % RDF (N+K) at 3 days interval through fertigation (T9), 100 % RDF (N+K) at 5 days interval through fertigation(T10) and 100 % RDF (N+K) at 7 days interval through fertigation(T11). All observations were recorded from winter season crop. Treatment T11 (100 % RDF (N+K) at 7 days interval through fertigation) additional produced fruit yield of 8.12 q ha-1 in comparison to the farmer’s practices (T1).

Rice genotype and fertilizer management for improving rice productivity under saline soil conditions

Soil salinity is a threat to crop production in the Senegal River Delta where salt intrusion increases soil electrical conductivity and most of farmers had abandoned their rice farms. The objective of this study was to evaluate an integrated management to improve rice productivity under saline soil condition in the Senegal River Delta. Field experiments were conducted during four rice-growing seasons from July 2014 to July 2016 at Africa Rice Center research station at Ndiaye, Senegal. The performance of five rice genotypes (IR63275-B-1-1-3-3-2, WAS73-B-B-231-4, NERICA-L9, FL478, and IR29) was evaluated under three salinity levels (0.5–0.8 dS m−1, 2.0 dS m−1, 3.5 dS m−1) and two fertilizer management options (basal dressing at 100 kg ha−1 of N–P–K (15–15–15) only and basal dressing at 200 kg ha−1 of N–P–K (15–15–15) + 50 kg N ha−1 urea at panicle initiation and at booting. Rice seedlings were raised at nursery for 21 days and transplanted at the density of 20 cm × 20 cm around March 15 and August 15 and harvested around July 15 and early December. The plots were drained canal when soil EC increased 0.1 dS m−1 above the designed EC levels. The results showed that rice yield decreased with the increasing soil salinity and were season dependent. Rice grain yield varied from 0.9 to 8 tons ha−1. Rice grain yield was 20% higher during the hot and dry seasons than the wet season. The application of the recommended fertilizer improved rice yield by 52% compared to the basal fertilizer application only. Nitrogen application at panicle initiation and at booting stages in addition to the basal fertilizer application doubled rice grain yield and should be adopted under salinity condition across the Senegal River Delta. The analysis of the combination of yield index, yield stability index, stress susceptibility index and the stress tolerant index indicated that the newly developed rice genotypes IR63275-B-1-1-3-3-2 and WAS73-B-B-231-4 showed high salt tolerance with better yield stability and low stress susceptibility and constitute good candidate to be adopted under the best fertilizer management option in the Senegal River Delta climate, soil salinity and similar environmental conditions.

鉄コーティング湛水直播栽培における全量基肥施肥が飼料用米'中生新千本'の収量に及ぼす影響

鉄コーティング湛水直播栽培における全量基肥施肥が飼料用米'中生新千本'の収量に及ぼす影響

Versatile Strip Seed Drill: A 2-Wheel Tractor-Based Option for Smallholders to Implement Conservation Agriculture in Asia and Africa

Smallholders in Asia and Africa require low-cost seed drills for minimal soil disturbance while establishing various crops. A seed drill that can be drawn by the widely-available two-wheel tractor (2WT) is an attractive option for mechanization of no-till in small-sized fields. The Versatile Strip Seed Drill (VSSD) was designed with the capacity to make up to 40 mm wide and 60 mm deep strips in untilled land along with seed and basal fertilizer application in a single-pass operation, while powered by the 8.95 to 11.93 kW 2WT. An important innovation of the VSSD was to fit the seed box with both fluted roller-type seed meters for delivery of sufficient small-size seeds to achieve adequate plant density per unit row length; and vertical disk-type seed meters for precision and spaced row planting of larger seeds. Both incessant seed dropping by fluted roller seed meters and spaced planting by vertical disk type seed meters provided optimum plant populations that were generally higher than in conventional, full-tillage plots with the same rate of hand broadcasted seed and fertilizers. Time required for crop establishment by VSSD ranged from 0.13 to 0.18 ha·h−1. When the VSSD was attached to the 2WT for crop establishment, the diesel fuel consumption varied from 4.4 to 6.1 L·ha−1, which was lower than for most 2WT-based planters previously used in Bangladesh. In on-farm multi-locations trials, wheat crops established with the VSSD had statistically similar grain yield compared to conventional tillage; however, significantly higher grain yield was obtained from mustard and lentil, by 14% and 19%, respectively. The VSSD is a unique, minimum-soil-disturbance multi-crop planter, and can be a platform on which to build conservation agriculture systems for small farms in Asia and Africa.

Effect of foliar spray of water soluble fertilizer at pre flowering stage on yield of pulses

Field experiments were conducted at Pulses and Oilseeds Research Station, Berhampore, Murshidabad, West Bengal during <italic>pre kharif, kharif and rabi</italic> seasons of 2011-12, 2012-13 and 2013-14 to study the effect of water soluble fertilizer spray on growth and yield of greengram, blackgram, lathyrus, lentil and chickpea. Pulses are mostly grown by the farmers without any fertilizer application, as positive effect of supplying legume plants with supplementary nitrogen was found to have beneficial effect on enhancing growth and increasing seed yield. Five sets of experiments were laid out in a split plot design with three replications <italic>viz.</italic> two levels of basal fertilizer application (F<sub>0</sub> -No basal dose of fertilizer, F<sub>1</sub> -Basal dose of fertilizer application @ 20, 40, 40 kg N, P<sub>2</sub>O<sub>5</sub>, K<sub>2</sub>O ha<sup>−1</sup>.) as factor A in main plot and seven levels of foliar spray of water soluble fertilizers at pre flowering stage (no spray, 0.5% NPK(19-19-19), 1% NPK(19-19-19), 2% NPK(19-19-19), 3% NPK(19-19-19), 2% DAP, 2% Urea) as factor B in sub plot. Significantly higher seed yield of pulses were recorded with application of 2% urea spray over basal dose of fertilizer application The lowest seed yield was recorded with no basal fertilizer and spray. Without basal dose of fertilizer application, 3% NPK (19-19-19) spray recorded highest seed yield. Under basal dose of fertilizer application, the results showed a gradual increase in yield with the increase in concentration of NPK (19-19-19) fertilizer spray up to 2%, Among the fertilizer spray treatments irrespective of basal dose of fertilizer application, urea spray was significantly better than all other treatments.

Parameterization of leaf growth in rice (Oryza sativa L.) utilizing a plant canopy analyzer

Monitoring leaf growth is a useful method for evaluating crop growth. In this study, frequent measurements of the rice canopy were conducted with a plant canopy analyzer, and parameters were estimated by applying several equations to evaluate leaf growth. The applicability of this evaluation method is discussed based on the statistical analysis of parameters. Experiments were conducted for 6 rice cultivars under 5 treatments in 2 years. Parameters describing the dynamics of leaf growth were obtained by applying 4 mathematical growth models in which the independent variable was the effective accumulated temperature. The parameters numerically represented the dynamics of leaf growth in each cultivar and treatment. In particular, maximum LAI and interception growth rates (MLGR and MIGR) which were obtained by applying logistic function to leaf area index (LAI) and diffuse non-light intercepted (DIFN), respectively, showed no interaction between the cultivar and environment. The lack of interaction may indicate that these parameters typically characterize cultivar and growth environments. The differences in the parameters could also be used to quantify the effect of basal fertilizer application on leaf growth enhancement and that of additional fertilizer on the extension of this enhancement. These results suggest that the applied method for parameterizing leaf growth based on frequent measurements with a canopy analyzer is suitable for evaluating the effects of genotype, management and the environment because it facilitates measurements in many plots.

Root and shoot growth of soybean (Glycine max) as influenced by naturally available phosphorus nutrition with manure

Effect of rock phosphate (RP) combined with cattle manure (CM) on plant growth of soybean was studied. As basal fertilizer application, RP at different levels (0, 25, 50, 75 and 100 kg/ha) along with 10 tons/ha CM (T2-T6) were applied and also recommended chemical fertilizer (T1 as a control). The results revealed that seed-pod ratio ranged from 0.68 to 0.74 at the maturity stage (12 weeks) and the highest ratio (0.74) was reported in RP (50 kg/ha) with CM (T4) and lowest value (0.68) was observed when CM solely applied. Further, the plants grown in inorganic fertilizer had a high root-shoot ratio (1:17) while comparatively lower ratios (1:12 to 1:15) were noted in plants grown with RP (0-100 kg/ha) and CM. Application of CM alone or in combination with RP at the optimal level could improve root and shoot growth for better yield of the soybean with less environmental pollution.

Nitrogen and phosphorus leaching losses from intensively managed paddy fields with straw retention

A field experiment was carried out for three years to examine the concentrations of NH4+-N, NO3−-N and dissolved total phosphorus (TP) in leachates and cumulative leaching losses in rice fields with straw retention under different rates of fertilizer N application. With straw retention, the percolation rate had a significant (p<0.05) negative exponential relationship with the day after rice transplanting, accounting for an average 2.57mmd−1. NH4+-N and NO3−-N concentration in percolation increased with increasing of N fertilizer application rate. Compared to the control (without straw or fertilizer), the wheat straw incorporation with nil N fertilizer decreased the concentration of NH4+-N and NO3−-N but promoted TP concentration. Cumulative inorganic N (NH4+-N+NO3−-N) and P losses were about 14.4 and 0.53kgha−1, accounting for 5.6% and 3.5% of N and P fertilizer applied. NH4+-N leaching losses accounted for 62–97% of the total leaching of inorganic N. Nitrogen leaching losses occurred mainly at the basal fertilizer application stage, accounting for 76.8% of total N leaching. Straw retention reduced the N leaching losses because the straw can enhance microbial N immobilization due to its high C:N ratio. However, the mechanism of straw incorporation impacts on N and P leaching requires more detailed study.

The Effect of Cattle Manure Enriched With ERP Fertilizer on Seed Yield of Soybean (Glycine max) in Sandy Regosol

The experiment was carried out in the Eastern region of Sri Lanka to evaluate the effect of cattle manure with different levels of rock phosphate application on seed yield of soybean ( Glycine max ) in sandy regosol. The air dried cattle manure (CM) (10 t/ha) with ERP fertilizer (eppawela rock phosphate) at 0-100 kg/ha and also recommended chemical fertilizers as a control were applied two weeks and two days before sowing respectively as a basal fertilizer application. The six treatments were arranged in a randomized complete block design with four replications. The yield response to each treatment was observed at the harvesting stage. The results revealed that significant differences (P Journal of Food and Agriculture 2010 Vol. 03, No. 1 & 2, Page 24-30 DOI: http://dx.doi.org/10.4038/jfa.v3i1-2.5167

Nitrous oxide emissions from Chinese maize–wheat rotation systems: A 3-year field measurement

Nitrous oxide (N2O) fluxes were measured over a 3-year period (2004–2007) in a long-term experimental field. The objectives of the study were to evaluate the interannual variation of N2O emissions from a maize–wheat rotation, under different fertilizer regimes and to determine the key controlling factors. The study involved four treatments: compost (OM), half compost N plus half inorganic fertilizer-N (HOM), inorganic fertilizer-N (NPK), and control (CK) where no N application. The mean annual N2O emission over a 3-year period was 0.30 ± 0.11 kg N2O–N ha−1 in the CK treatment, but increased to 1.61 ± 0.10 kg N2O–N ha−1 in the HOM treatment, 2.13 ± 0.15 kg N2O–N ha−1 in the OM treatment, and 2.76 ± 0.19 kg N2O–N ha−1 in the NPK treatment. Differences were significant among treatments. The N2O emission factors of the applied OM, NPK and HOM were 0.61 ± 0.02, 0.82 ± 0.10 and 0.44 ± 0.04%, respectively, at a rate of 300 kg N ha−1 year−1, indicating that the combined application of compost with inorganic fertilizer significantly reduced N2O emission. Over a maize–wheat rotation year, more than 65% of the annual N2O emission occurred during the maize growing season. There was a large interannual variation in N2O emission in all treatments, albeit not significant either during the maize growing season or at an inter-year scale. This interannual variation was mainly attributable to differences in soil moisture after basal fertilizer application, and irrigation and/or heavy rainfall events immediately following basal fertilization could induce more N2O production than pre-irrigation before plowing. The HOM treatment had higher N fertilizer use efficiency and lowest yield-scaled N2O emissions compared with the OM and NPK treatments. We therefore argue that the combined application of half compost N plus half fertilizer-N will mitigate N2O emissions from soils in the North China plain.

Evaluation of a Multiple Linear Regression Model for the Prediction of Panicle Number in Rice

In Japan, it is required to develop rice production technology that can achieve stable targets of yield and quality, given the high demands of consumers about rice quality, the necessity of enhancing our international competitive power, and a declining trend in the production of first grade rice (Ministry of Agricultaure, Forestry and Fisheries, 2011). Rice yield is determined by yield components such as panicle number, spikelet number, percentage of ripened grains, and grain weight (Kokubun, 2010). Among these components, panicle number is the most important because it significantly affects other yield components as well as rice quality. Panicle number is largely determined by tiller number, which is affected by various factors such as air temperature (Kobayashi et al., 1985), solar radiation (Shimizu et al., 1962; Kitagawa et al., 1988), water temperature (Honjo et al., 1968; Ueki, 1968), and soil nitrogen content (i.e., quantity of ammo–nium in the soil solution and exchangeable ammonium in the soil (Ando et al., 1988). Yet, the interaction of these factors is complicated; thus, tiller number has mainly been controlled on the basis of trial and error experiences of farmers. However, unstable rice yield and quality in recent years indicate limitation of agricultural practice when based on farmer experience. Hence, the development of a prediction model that expresses the relationship between tiller or panicle number and various influential factors is required to support the decision–making process of farmers in agricultural practice. There has been a limited number of studies regarding prediction models on tiller or panicle number, with such studies being focused on factorial analysis. Tanifuji and Thokairin (1985) developed the successive prediction model for tiller and panicle numbers that focused on short–term forecasts. In this model, tiller and panicle numbers were predicted 10 to 20 days in advance by using plant length and tiller number at the time of prediction and daily mean temperature of ordinary year. This model may provide useful information to support decision–making for top–dressing; however, the model does not provide information about required basal fertilizer application, which is the most important practice to control tiller number. In addition, the explanatory variables included in the model were not sufficient to express Evaluation of a Multiple Linear Regression Model for the Prediction of Panicle Number in Rice

Nitrification, ammonia-oxidizing communities, and N2O and CH4 fluxes in an imperfectly drained agricultural field fertilized with coated urea with and without dicyandiamide

Agricultural soil is a major source of nitrous oxide (N2O), and the application of nitrogen and soil drainage are important factors affecting N2O emissions. This study tested the use of polymer-coated urea (PCU) and polymer-coated urea with the nitrification inhibitor dicyandiamide (PCUD) as potential mitigation options for N2O emissions in an imperfectly drained, upland converted paddy field. Fluxes of N2O and methane (CH4), ammonia oxidation potential, and ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) abundances were monitored after the application of PCU, PCUD, and urea to upland soil. The results showed that urea application increased the ammonia oxidation potential and AOB and AOA abundances; however, the increase rate of AOB (4.6 times) was much greater than that of AOA (1.8 times). These results suggested that both AOB and AOA contributed to ammonia oxidation after fertilizer application, but the response of AOB was greater than AOA. Although PCU and PCUD had lower ammonia oxidation potential compared to urea treatment, they were not effective in reducing N2O emissions. Large episodic N2O emissions (up to 1.59 kg N ha−1 day−1) were observed following heavy rainfall 2 months after basal fertilizer application. The episodic N2O emissions accounted for 55–80 % of total N2O emissions over the entire monitoring period. The episodic N2O emissions following heavy rainfall would be a major source of N2O in poorly drained agricultural fields. Cumulative CH4 emissions ranged from −0.017 to −0.07 kg CH4 ha−1, and fertilizer and nitrification inhibitor application did not affect CH4 oxidation.

Effect of N-fertilizer application on return flow water quality from a terraced paddy field in Northern Taiwan

Intensive use of chemical fertilizer for crops may be responsible for nitrogen and phosphate accumulation in both groundwater and surface waters. The return flow polluted by nutrients not only results in the limitation of water reuse goals but also creates many environmental problems, including algal blooms and eutrophication in neighboring water bodies, posing potential hazards to human health. This study is to evaluate the N-fertilizer application of terraced paddy fields impacting return flow water quality. Water quality monitoring continued for two crop-periods around subject to different water bodies, including the irrigation water, drainage water at the outlet of experimental terraced paddy field, and shallow groundwater were conducted in an experimental paddy field located at Hsin-chu County, Northern Taiwan. The analyzed results indicate that obviously increasing of ammonium-N (NH4 +-N) and nitrate-N (NO3 −-N) concentrations in the surface drainage water and ground water just occurred during the stage of basal fertilizer application, and then reduced to relatively low concentrations (<0.1 mg/l and <3 mg/l, respectively) in the remaining period of cultivation. The experimental results demonstrate the potential pollution load of nitrogen can be reduced by proper drainage water control and fertilizer application practices.

Direct-seeded rice culture in Sri Lanka: Lessons from farmers

About 95% of the rice grown in Sri Lanka is direct-seeded (wet- and dry-seeding). The average rough rice yield in irrigated predominantly direct-seeded dry zone (DZ) is about 5.0 t ha −1and in the wet zone (WZ) it is about 3.3 t ha −1. However the average realizable yield in DZ and WZ are 8 t ha −1 and 5 t ha −1 respectively. A survey was conducted to understand the cultural practices, farmers’ perceptions and the reasons for the yield gap in direct-seeded rice culture in Sri Lanka. Farmers’ seed rate ranged from 87 to 220 kg ha −1 for intermediate bold-type varieties and from 71 to 176 kg ha −1 for varieties with short round grains. About 90% of the farmers in the DZ and the intermediate zone (IZ) consider both yield potential and duration as criteria in selecting a variety. Among the farmers surveyed, only 21% of the farmers in the DZ, 13% of the farmers in the IZ, and 29% of the farmers in the WZ adhered to the recommended method of basal fertilizer application. Farmers did not adhere to the correct timing of fertilizer application. More than 50% of the cost for rice farming goes to labor, followed by cost of inputs in all climatic zones. Farmers reported that the most important production constraint for direct-seeded rice in the DZ and IZ is the non availability of reliable labor followed by soil problems and weeds. While in the WZ, it is the soil problems specially iron toxicity followed by lower soil fertility. The survey revealed that smaller land holding size, non adherence to the optimum time of farm activity initiation, less efficient use of rain water, higher seed rate and higher cost of production are a few reasons for the existing yield gap. Location-specific technologies for different agro-ecological zones of Sri Lanka should be developed to reduce the cost of production and to increase resource-use efficiency and should be transferred to the farmers to achieve sustainable optimum direct-seeded rice yields.

Lodging resistance locus prl5 improves physical strength of the lower plant part under different conditions of fertilization in rice ( Oryza sativa L.)

High fertilizer application rates increase grain yield and biomass in rice, but reduces lodging resistance. Lodging resistance locus prl5 enhances pushing resistance through delaying leaf senescence and increasing carbohydrate reaccumulation in stems. This study demonstrates the effects of prl5 under different levels of Nitrogen·Phosphorus·Potassium basal fertilizer application using a chromosome segment substitution line based on the genetic background of Koshihikari, which contains prl5. High fertilizer application rates enhanced pushing resistance of the lower part, but did not consistently affect the pushing resistance of the whole plant. Independent of fertilizer application rates, prl5 enhanced pushing resistances of both the lower part and the whole plants. Plant height, biomass and grain yield were increased by high fertilizer application rates, but stem diameter and the dry weight of basal culms did not show consistent increases as determined over a period of 2 years. In leaves just after heading, chlorophyll (Chl) contents, rather than Rubisco contents, were correlated with fertilizer application rates. At the fully ripe stage, fertilizer application did not affect Chl and Rubisco contents in leaves, while prl5 increased the contents in the second leaf. High fertilizer application rates did not affect the concentration of non-structural carbohydrates (NSCs) in basal culms, but prl5 increased them at the fully ripe stage. These results suggest that fertilizer application reduces lodging resistance by highly elevating the center of gravity, but that prl5 can counteract this effect by enhancing the physical strength of the lower part through delaying leaf senescence and increasing NSC reaccumulation in culms without any effects of different fertilizer application rates.

Effect of Successive Cultivation Using Single Whole Basal Fertilizer Application to the Nursery Box on the Growth and Yield of Paddy Rice under Early and Normal Season Culture in Tomo Area of Gunma Prefecture

群馬県東毛地域の早植・普通期水稲栽培において育苗箱全量基肥施肥法によって継続して栽培を行い, 水稲の生育・収量の変動について検討した. この地域の土壌はグライ土から成る肥沃な水田地帯である. 館林市の現地圃場で「苗箱まかせNK301-100」を供試し, 4か年継続して水稲を栽培した. 施肥量は本田における標準体系の基肥と追肥合計窒素施肥量の40％減とした. 前年作の稲わらは全量すき込みとして, 専用肥料に不足している燐酸, 加里成分は本田に施用しなかった. 1年目は標準体系に対する施肥量が実測値で49％減となり, 生育・収量は標準体系に比べて不足気味となった. 2～4年目は同38～45％減の施肥量であったが, 生育に明らかな差は認められなかった. 3年目は著しい虫害が発生したため, 4年目に3年目と同様の設計で追加試験を行った. 収量までの検討は3年間であったが, 継続施用による収量等の低下は特に発生しなかった. 肥沃な土壌条件であれば, 概ね減肥率40％で稲わらを圃場に全量還元することによって化学肥料として燐酸, 加里の不足分の補給を行わなくても標準体系と遜色ない生育・収量を得られることが明らかとなった.

Effects of Fused-Phosphate-Covering and Extension of Seedling Raising Period in the Culture of Paddy Rice by Single Whole Basal Fertilizer Application to the Nursery Box in Gunma Prefecture

Effects of Fused-Phosphate-Covering and Extension of Seedling Raising Period in the Culture of Paddy Rice by Single Whole Basal Fertilizer Application to the Nursery Box in Gunma Prefecture