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Given the importance of crop yield and yield progress, this review endeavours to clearly define the different representations of yield, discuss their measurement, and elucidate some controlling factors in yield change. For a field...
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Given the importance of crop yield and yield progress, this review endeavours to clearly define the different representations of yield, discuss their measurement, and elucidate some controlling factors in yield change. For a field, farm, district or region, average farm or actual yield (FY) is central, but potential (and water-limited potential) yield (PY, PYw) is also an important yardstick. PY is defined here as the measured yield of the best cultivar, grown with optimal agronomy and without manageable biotic and abiotic stresses, under natural resource and cropping system conditions representative of the target area. Economic yield, governed by considerations of profit and risk, and record and theoretical yield, complete the picture. Yield gap is defined as the difference between PY and FY under the same environment. Across most crop-region combinations in the last 2 to 3 decades, FY progress has been associated with both PY progress and yield gap closing, and a simple model, based on linear regression against time, is proposed for understanding this. PY advance is the result of plant breeding and new agronomy (and their interaction, usually positive), while yield gap closing arises with the adoption by farmers of known innovations faster than new ones are invented. Unravelling the true technological component in apparent progress in PY, and especially in FY, is not necessarily simple, and confounding factors are listed and discussed. (C) 2014 Elsevier B.V. All rights reserved.
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Regression analyses of the relationships between yield and time over the last century were conducted for wheat, barley, oats, maize, and rice at a national level and those for the three winter cereals in New South Wales (NSW), Vic...
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Regression analyses of the relationships between yield and time over the last century were conducted for wheat, barley, oats, maize, and rice at a national level and those for the three winter cereals in New South Wales (NSW), Victoria (Vic), South Australia (SA), Western Australia (WA), and Queensland (Qld). The fitted function accounts for the impact of agronomic improvement on yield and the residuals stand for the variability of yield beyond this impact. Another measure of the stability was obtained by considering the residuals as a proportion of actual yield ('relative residuals'). Crops varied greatly in their yields but there was no relationship between the coefficient of variation and average yield amongst these cereals. As expected, yields of all five crops are presently higher than early this century. The residuals and relative residuals for each crop were plotted against years. Residuals of wheat yields over time showed no increase or decrease during the century, but the relative residuals exhibited a clear trend towards an increased yield stability. Barley and oats showed sirnilar patterns to those of wheat. Residuals of maize yields increased with time, but relative residuals remained unchanged. Rice yields exhibited the largest residuals, but no trends with time. Yield stability, measured as a proportion of yield, has been clearly improved during this century. Yield trends for the winter cereals at a State level confirmed the results observed at a national level. In conclusion, yields of newer cultivars grown under modern management were higher and more stable, or at least not less stable, than those of crops grown early in the century. Across States and crops, there was no relationship between yield stability and yield.
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Yield of rubber tree varies over the years depending on many biological, environmental and management factors. In an experiment, the latex yield of 12 Hevea clones was monitored for 16 years under S/2 d2 6 d/7 system of tapping. T...
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Yield of rubber tree varies over the years depending on many biological, environmental and management factors. In an experiment, the latex yield of 12 Hevea clones was monitored for 16 years under S/2 d2 6 d/7 system of tapping. The yield increased gradually in initial years of tapping and maintained a higher yield output from 3rd to 15th year. Yielding pattern of rubber trees varied among the clones. Clone PB 235 and RRII 118 showed a long duration of higher yield output for 15 years. Clones RRII 300, RRII 105, RRIM 501 and PR 107 exhibited higher yield output for 8 to 10 years. After a specific period of vigorous latex output, the yield started declining in all clones. The onset of yield decline was different among the clones and it varied from 11th to 16th year of tapping. In clones RRII 105 and RRIM 703, the yield decline commenced from 12th year of tapping, whereas this was between 15th to 16th year of tapping in clones PB 235, RRII 118, RRIM 600, GT1 and Gl 1. Generally, a drastic reduction in yield was observed after 16 years of tapping when the trees were 23 years old. Clones RRIM 703 and RRIM 501 showed the highest decline (40%) from peak yield at 16th year of tapping. The popular clone RRII 105 recorded around 20 per cent decline. This was almost negligible in clones RRII 118 and Gl 1. The decline in yield of rubber trees could be attributed to ageing, soil fertility, environmental and agro-management factors that might reduce the tree growth and shorten the economic life span of trees.
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Yield enhancements and quality improvements must be considered as factors of the utmost importance in VLSI (Very Large Scale Integration circuits) manufacturing in order to reduce cost and ensure customer satisfaction. This paper ...
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Yield enhancements and quality improvements must be considered as factors of the utmost importance in VLSI (Very Large Scale Integration circuits) manufacturing in order to reduce cost and ensure customer satisfaction. This paper will present a study of the yield theory, an analysis of actual manufacturing data, and the challenges of yield enhancement.
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To reduce the yield gap, specifying yield constraints in a particular area is necessary. A complete yield gap assessment method must provide information regarding potential yield, actual yield, and causes of the gap and their impo...
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To reduce the yield gap, specifying yield constraints in a particular area is necessary. A complete yield gap assessment method must provide information regarding potential yield, actual yield, and causes of the gap and their importance. Therefore, documenting the production process to explain crop management factors in each area is very important. The objective of the study was to perform a rice yield gap analysis by using comparative performance analysis (CPA) and boundary-line analysis (BLA). Datawere gathered from about 100 paddy fields in Neka, eastern Mazandaran province, one of the major rice producing regions in Iran, in 2015 and 2016. All agricultural practices from nursery preparation to harvest have been recorded for improved rice cultivars. CPA focuses on the ability to estimate potential yield and the reason for a yield gap. Boundary lines were fitted to the edge of the data cloud of crop yield versus management variables in data from paddy fields monitoring. The documenting analysisshows that the range of paddy yield in 100 fields varied from 6100 to 8200 kg ha~(-1). Potential yields were 9241 kg ha~(-1) for CPA method, and 7999 kg ha~(-1) for BLA method. Furthermore, yield gap predicted 2047 kg ha~(-1) for CPA method and 874 kg ha~(-1) for BLA method. In BLA, the average relative yield and relative yield gap of the 13 investigated variables were 89.75% and 10.25% respectively. These results show the importance of each management factor in yield gap. It was concluded that CPA andBLA as applied in thestudy is a cheap and simple method that, without the need for expensive experimentation, is able to detect yield gap and its causes in a district. From these results, it can be said that the calculated yield gap is close to the definition given for the utilised yield gap and shows the difference between the actual yield and attainable yield in relation to the environmental conditions of the region.
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A field experiment was conducted during November 2009-April 2010 in Bangladesh Rice Research Institute, Bangladesh to examine the response of two rice (Oryza sativa L.) varieties (BRRIdhan28 and BRRI dhan29) to six N rates of nitr...
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A field experiment was conducted during November 2009-April 2010 in Bangladesh Rice Research Institute, Bangladesh to examine the response of two rice (Oryza sativa L.) varieties (BRRIdhan28 and BRRI dhan29) to six N rates of nitrogen fertilizer viz. 0, 50, 100, 150, 200 and 250 kg ha-1. The experiment was conducted in a RCB design with three replications. Grain yields of both BRRI dhan28 and BRRI dhan29 increased significantly in a quadratic fashion with N rates. The highest grain yields were obtained from 150 kg N ha-1 in both the varieties. More than 1 t ha-1 yield was obtained in BRRI dhan29 (6.34 t ha-1) at the same rate of N indicated BRRI dhan29 as a nitrogen efficient variety. However, the predicted economic optimum doses of N appeared to be 156 and 158 kg ha-1 for BRRI dhan28 and BRRI dhan29, respectively. The grain yield was mainly influenced by the number of panicles per hill, which was found to increase with the increase of N rates in both the varieties.
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A field experiment was carried out during the summer season of 2015 at research farm of Afghanistan National Agricultural Sciences and Technology University (ANASTU), Kandahar, Afghanistan in randomized complete block design to fi...
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A field experiment was carried out during the summer season of 2015 at research farm of Afghanistan National Agricultural Sciences and Technology University (ANASTU), Kandahar, Afghanistan in randomized complete block design to find out the effect ofdifferent combinations of nitrogen (N) and phosphorus (P) fertilization on growth, yield attributes and yield of hybrid maize (Zea mays L.) 'CS-200'. The treatments consisted of 8 combinations of N : P205 in 2 : 1 ratio, viz. control, 20 : 10, 40 : 20, 60 : 30, 80 : 40, 100 : 50, 120 : 60 and 140 : 70 kg/ha and replicated thrice. Significantly higher growth and yield attributes, viz. plant height (194 cm), number of green leaves (13.3/plant), leaf-area index (4.81), dry-matter accumulation (289 g/plant), cob length (20.7 cm), cob girth (12.9 cm), cob diameter (3.97 cm), cobs/plant (1.57), grain rows/cob (14.8.), grains/row (37.7), gains/cob (514), 1,000-grain weight (276 g), grain yield (6.3 t/ha) and stover yield (15.6 t/ha) were recorded with 140 : 70 N : P205 kg/ha. The findings of the study concluded that to realize the higher yield of hybrid maize in Kandahar province of Afghanistan, the crop should be fertilized with 140 : 70 N : P205 kg/ha.
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Australian dry-land crop producers farm in regions with highly variable climate and soils. Farmers have responded to the pressures of rising costs by pioneering and adapting new technologies to narrow the gap between actual and wa...
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Australian dry-land crop producers farm in regions with highly variable climate and soils. Farmers have responded to the pressures of rising costs by pioneering and adapting new technologies to narrow the gap between actual and water-limited yield. With yields reaching a plateau in many of the developed world's cropping areas, it is possible that Australia's leading farmers have similarly closed the exploitable yield gap and require technological breakthroughs to sustainably push the production frontier to new and higher levels. To assess the potential for Australian farmers to continue closing the yield gap, and possibly increase water-limited yield, the long-term farm production records of individual wheat fields of three leading farmers in South East Australia were used to ascertain the applicability of modelling to develop new and innovative practices. The cropping systems simulator APSIM was used to establish the attainable simulated yield based on the farmers' chosen management inputs for wheat crops over a period of 16-20 years. A strong relationship (r(2) = 0.89, RMSD = 508 kg ha(-1)) was found between actual and simulated yields. This relationship indicates that yield-reducing factors not simulated by APSIM (weeds, disease etc.) were largely controlled on these farms and confirms APSIM's suitability for this analysis. Over the 16-20 year study period, the average yield gaps on the three farms ranged from 480 to 770 kg ha(-1); representing between 74 and 82% of their water-limited yield potential. For these leading farmers, the yield gap is only small and unlikely to be economically exploitable under current management practices. Consequently, three tactical management innovations with potential to improve farm wheat yield and reduce risk were evaluated. One innovation investigated whether farmers practicing no-till crop establishment, who were able to control weeds prior to sowing, could benefit from sowing current cultivars earlier than present-day practice. It was found that leading farmers are already sowing at the optimum time and sowing earlier would not increase yield because of greater risk of frost damage. Two other innovations were found to have practical application. The first used Yield Prophet (R) to assist farmers decide when to apply in-crop nitrogen fertiliser based on a more complete understanding of nitrogen and water requirements of crops in variable growing seasons. The second innovation involved sowing slow maturing wheat cultivars earlier than current practice but only in years with adequate stored soil water and early season rainfall. Both innovations were found to increase grain yield and reduce risk of over- or under-application of nitrogen fertiliser. Investigation of strategic and tactical management options to increase yield using simulation modelling for subsequent evaluation in the field has the potential to keep Australian farmers at the forefront of innovations in crop production. (C) 2014 Elsevier B.V. All rights reserved.
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An experiment was conducted at Jimma University College of Agriculture and Veterinary Medicine (JUCAVM) experimental field to evaluate selected tomato (Lycopersicon esculentum Mill.) varieties for their seed yield under irrigated ...
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An experiment was conducted at Jimma University College of Agriculture and Veterinary Medicine (JUCAVM) experimental field to evaluate selected tomato (Lycopersicon esculentum Mill.) varieties for their seed yield under irrigated condition. The experiment was set using a Randomized Complete Block Design (RCBD) with three replications wherein nine tomato varieties: five determinate type (Bishola, Chali, Cochoro, Fetan and Melkasalsa) and four semi-determinate type (Metadel, Miya, Melkashola and Arp tomato d2) and one local variety (Roma VF) were used. Data was collected on yield, seed weight per fruit, seed weight per plant, seed yield per hectare, number of seed per fruit, thousand seed weight, fruit diameter, fruit weight per plant and fruit yieldper hectare. The results revealed that Variety had highly significantly (p<0.01) affected the yield and yield component parameters. Significantly the highest fruit diameter (6.25 cm) was recorded from variety Bishola whereas the lowest seed yield per hectare was obtained from Fetan (58.1 kg). Correlation analysis also indicated that Seed weight per plant was significantly and positively associated with seed weight per hectare (r = 0.95), fruit yield per hectare (r = 0.40) and fruit weight per plant (r =0.40). Fruit weight per plant was highly significantly and positively correlated with seed weight per hectare (r = 0.47) and fruit yield per hectare (r = 0.99). The tomato variety Bishola was found to be high seed yielder as compared to the other varieties compared and hence it is suggested that tomato producers in Jimma area can use Bishola variety for high seed yield.
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Effects of micronutrients [molybdenum (Mo), boron (B), iron (Fe), zinc (Zn), manganese (Mn) and copper (Cu)] on seed yield and yield components (seed yield per unit area, fertile shoots per unit area, number of racemes per shoot, ...
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Effects of micronutrients [molybdenum (Mo), boron (B), iron (Fe), zinc (Zn), manganese (Mn) and copper (Cu)] on seed yield and yield components (seed yield per unit area, fertile shoots per unit area, number of racemes per shoot, number of pods per raceme, number of seeds per pod and 1000-seed weight) of alfalfa were investigated in the northwest region of China, over two seasons (2003-2004) on a torrifluvent soil and a site of 1720 m altitude. After two years study, it demonstrated that molybdenum and boron were more critical for alfalfa seed production. Molybdenum increased seed yield by 27-47%, the number of racemes per shoot by 38-55%, the number of pods per raceme by 100-133%, the number of seeds per pod by 48-61% and 1000-seed weight by 24%, and boron increased seed yield by 22-35%, fertile shoots per unit area by 17-35%, the number of racemes per shoot by 38-64%, the number of pods per raceme by 100%, the number of seeds per pod by 41-52% and 1000-seed weight by 16%. Iron, manganese, and copper had any effect on yield components, but they had no effect on seed yield. Zinc had no positive effect on seed yield and yield components. Among seed yield components, the number of pods per raceme was the most important factor to determine alfalfa seed yield. Results from this study will be used to recommend further evaluation of molybdenum and boron across a number of environments around the world and as a basis for developing recommendations to the alfalfa seed production industry.
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