Low Yield Years Research Articles

Year patterns of climate impact on wheat yields

ABSTRACTRainfall, temperature, and solar radiation are important climate factors, which determine crop growth, development and yield from instantaneous to decadal scales. We propose to identify year patterns of climate impact on yield on the basis of rain and non‐rain weather. There are inter‐related impacts of climatic factors on crop production within a specific pattern. Historical wheat yield data in Queensland during 1889–2004 were used. The influence of meteorological conditions on wheat yields was derived from statistical yield data which were detrended by 9‐year‐smoothing averages to remove the effects of technological improvements on wheat yields over time. Climate affects crop growth and development differently over different growth stages. Therefore, we considered the climate effects at both vegetative and reproductive stages (before and after flowering date, respectively) on yield. Cluster analysis was employed to identify the year patterns of climate impact. Five patterns were significantly classified. Precipitation during the vegetative stage was the dominant and beneficial factor for wheat yields while increasing maximum temperature had a negative influence. Crop yields were strongly dependent on solar radiation under normal rainfall conditions. As the effect of rainfall on soil water is relatively long‐lasting, its beneficial effect in vegetative stage was higher than its effect during the reproductive stage. The Agricultural Production Systems sIMulator (APSIM) was evaluated using long‐term historical data to determine whether the model could reasonably simulate effects of climate factors for each year pattern. The model provided good estimates of wheat yield when conditions resulted in medium yield levels, however, in extremely low or high yield years, corresponding to extremely low or high precipitation in the vegetative stage, the model tended to underestimate or overestimate. Under high growing season precipitation, simulations responded more favourably to reproductive stage rainfall than measured yields.

Foliar Potassium Fertilizer Additives Affect Soybean Response and Weed Control with Glyphosate

Research in 2004 and 2005 determined the effects of foliar-applied K-fertilizer sources (0-0-62-0 (%N-%P2O5-%K2O-%S), 0-0-25-17, 3-18-18-0, and 5-0-20-13) and additive rates (2.2, 8.8, and 17.6 kg K ha−1) on glyphosate-resistant soybean response and weed control. Field experiments were conducted at Novelty and Portageville with high soil test K and weed populations and at Malden with low soil test K and weed populations. At Novelty, grain yield increased with fertilizer additives at 8.8 kg K ha−1in a high-yield, weed-free environment in 2004, but fertilizer additives reduced yield up to 470 kg ha−1in a low-yield year (2005) depending on the K source and rate. At Portageville, K-fertilizer additives increased grain yield from 700 to 1160 kg ha−1compared to diammonium sulfate, depending on the K source and rate. At Malden, there was no yield response to K sources. Differences in leaf tissue K(P=0.03), S(P=0.03), B(P=0.0001), and Cu(P=0.008)concentrations among treatments were detected 14 d after treatment at Novelty and Malden. Tank mixtures of K-fertilizer additives with glyphosate may provide an option for foliar K applications.

Estimation of genetic data and breeding values of traits related to wax production in Rhus succedanea L. clones using the REML/BLUP method

Rhus succedanea L. is cultivated in Japan for the wax that can be extracted from its fruits. We determined genetic data for specific traits associated with wax production (fruit number per cluster, FN, fruit weight, FW, number of clusters per area, CN, and wax content, WC) in five traditional cultivars and 13 newer clones. Data were collected over 4 years and alternate bearing was observed: 2001 and 2003 were years with high yields; in 2002 and 2004 yields were poor. The restricted maximum likelihood method was used to calculate (co)variance components for analysis. Broad sense heritability was estimated and ranged from low (FN and CN) to high (FW and WC) for the traits examined. There were positive genetic correlations between FW and WC and negative ones between FN and FW throughout the 4 years. Genetic correlations between CN and the other traits were positive in good crop years and negative in bad crop years. For each assessed clone, the four traits in the 4 years were evaluated using best linear unbiased predictors (BLUP) of the clonal breeding values. The BLUP scores for both FW and WC exhibited positive correlations between pairs of years, whereas there were positive BLUP correlations for CN when the high yield and low yield years were examined separately. The traditional cultivars and the newer clones were also characterized. Some of the clones were better than the traditional cultivars with regard to wax yield and reliability of production. The trait characteristics and the future breeding are discussed.

Weather conditions associated with irrigated crops in an arid and semi arid environment

Climate variability and weather extremes are principal sources of fluctuations of annual productivity of many crops in arid and semi-arid environments. Temperature and precipitation are the major weather variables that determine the variability of crop yields. In this study, the relationship between weather descriptors and major irrigated crops yield were assessed for Khorasan province in northeast of Iran. Long term daily weather (1984–2007) and crop yield (wheat, barley, sugarbeet, cotton, potato, chickpea, alfalfa) data were analyzed with simple correlation analysis and also the iterative chi-square analysis identified relationships of low and high wheat yield years to maximum and minimum air temperatures within each region. Our results indicated that association between various crop yield and descriptors varied in different study location. As in Bojnourd located in the north of Khorasan yields of the crops studied did not correlate with temperature indicators, whereas in Birjand the relationship between temperature descriptors and crop yields were strong. Correlation between growing season precipitation and wheat, barley, chickpea and sugarbeet yields was positive while cotton yield decreased with increasing precipitation during the growing season. The results of chi-square analysis for wheat yield demonstrated that the critical time in which extreme temperature led to yield loss differed among regions. In Bojnourd, in late April to early May, and excess days (high or low yield years have more days meeting a cardinal value than normal years) with maximum temperature higher than 30°C, wheat yield decreased while in Birjand, cooler maximum temperature (≤10°C) and excess days with minimum temperature particularly lower than −5°C in mid-December were associated with low yielding year of wheat. Determination of critical periods when wheat is most sensitive to air temperature extremes provides important information for modifying management practices, such as adjusting planting date in order to decrease the negative impacts of these climatic extremes on yield.

Risk analysis of climate variability on food production in Hailun, Northeast China

粮食生产具有不确定性特征, 气候波动是影响粮食产量年际变化的主要因素之一。本研究采用风险分析方法, 基于海伦市22个乡镇1978~2007年大豆和玉米产量的统计资料, 以相对气象产量作为农作物受气候波动影响程度的指标, 采用非参数信息扩散方法中正态扩散模型, 对各乡镇大豆和玉米产量不同减产程度出现的概率进行了计算, 进而获得各乡镇大豆、玉米单产受气候波动影响的风险度。在此基础上, 基于海伦市气象站逐日降雨量和气温资料, 按照气候干燥度将所有年份分为偏干旱年份、正常年份和偏湿润年份, 分别计算不同水热耦合年份下各乡镇粮食产量受气候波动影响的风险程度。结果表明, 大豆和玉米极端减产年出现的概率高于极端高产年; 北部大豆减产风险小于南部, 玉米在总体上呈现出和大豆减产概率空间分布相反的趋势; 在不同水热耦合年份中, 海伦市旱田农作物生产风险具有空间差异性, 其中大豆生产风险空间分布与河网相关性较玉米高。

Yellow Nutsedge (Cyperus esculentus) Interference in Soybean

Field research was conducted in 2000 and 2001 to determine the effect of yellow nutsedge emergence timing and plant density on soybean yield and on yellow nutsedge propagation the following year. Yellow nutsedge tubers were planted at 0-, 7.5- (13/m2), 15- (8.6/m2), 30- (4.3/m2), 60- (2.2/m2), and 90-cm (1.5/m2) in-row spacings with soybean. Yellow nutsedge densities from 2.2 to 13 plants/m2in a high-yield year (2000) and 4.3 to 13 plants/m2in a low-yield year (2001) reduced grain yields 9 to 34%. In a separate experiment, tubers were planted 0, 2, 4, 6, and 8 wk after planting at a 15-cm (8.6/m2) in-row spacing. Seedlings that emerged with the crop and until 2 wk after planting reduced yield 9 to 11%. Yellow nutsedge densities from 1.5 to 13 plants/m2contributed to significant aboveground biomass production, even with a competitive crop, such as soybean. For every gram of aboveground yellow nutsedge biomass produced in the fall, there were more than four shoots present the following spring.

Analysis of biomass feedstock availability and variability for the Peace River region of Alberta, Canada

Biorefineries or other biomass-dependent facilities require a predictable, dependable feedstock supplied over many years to justify capital investments. Determining inter-year variability in biomass availability is essential to quantify the feedstock supply risk. Using a geographic information system (GIS) and historic crop yield data, average production was estimated for 10 sites in the Peace River region of Alberta, Canada. Four high-yielding potential sites were investigated for variability over a 20 year time frame (1980–2000). The range of availability was large, from double the average in maximum years to nothing in minimum years. Biomass availability is a function of grain yield, the biomass-to-grain ratio, the cropping frequency, and residue retention rate to ensure future crop productivity. Alternate feedstock sources must be identified to supply biomass processing facilities in low yield years.

Scheme of Weather-Based Indemnity Indices for Insuring Against Freeze Damage to Citrus Orchards in Zhejiang, China

We design a weather-based indemnity index for the insurance against freeze damage to citrus orchards so as to provide technological support for the development of policy-based agriculture. The indices are prepared by separating a relative meteorological yield from the yield that is dependent on tree age, high-yield and low-yield years, and environmental factors, and then using a risk assessment scheme to determine the percentage yield reduction due to the meteorological hazard. We thus develop a set of indices associated with cold temperature damage with which to construct more severe weather indices in conjunction with the yield percentage decrease. We then combine the insured regional citrus yield index with the insured meteorological counterpart to obtain a weather-based indemnity index for the varying degree of freeze damage to crops. When the freeze damage index (FDI) is greater than −7.0°C for the coastal belt of Zhejiang Province, China, or greater than −9.0°C for other regions of Zhejiang, weather-based indemnity index (WBII) is zero, meaning there is no compensation; when the FDI is from −7.0 to −7.9°C for the coastal belt or from −9.0 to −9.9°C for other regions, the WBII is 1 with 50% compensation; when the FDI is from −8.0 to −8.9°C for the coastal belt or from −10.0 to −10.9°C for other regions, the WBII is 2 with 70% compensation; and when the FDI is less than −9.0°C for the coastal belt or less than −11.0°C for other regions, the WBII is 3 with 90% compensation. The weather indemnity indices of insured orchards are developed in the interest of owners, thereby eliminating adverse selection and moral hazard issues and providing timely recompense from the insurer, and resolving the problem of high indemnity cost in agricultural insurance.

Climate Variability and Sugarcane Yield in Louisiana

Abstract This paper seeks to understand the role that climate variability has on annual yield of sugarcane in Louisiana. Unique features of sugarcane growth in Louisiana and nonclimatic, yield-influencing factors make this goal an interesting and challenging one. Several methods of seeking and establishing the relations between yield and climate variables are employed. First, yield–climate relations were investigated at a single research station where crop variety and growing conditions could be held constant and yield relations could be established between a predominant older crop variety and a newer one. Interviews with crop experts and a literature survey were used to identify potential climatic factors that control yield. A statistical analysis was performed using statewide yield data from the American Sugar Cane League from 1963 to 2002 and a climate database. Yield values for later years were adjusted downward to form an adjusted yield dataset. The climate database was principally constructed from daily and monthly values of maximum and minimum temperature and daily and monthly total precipitation for six cooperative weather-reporting stations representative of the area of sugarcane production. The influence of 74 different, though not independent, climate-related variables on sugarcane yield was investigated. The fact that a climate signal exists is demonstrated by comparing mean values of the climate variables corresponding to the upper and lower third of adjusted yield values. Most of these mean-value differences show an intuitively plausible difference between the high- and low-yield years. The difference between means of the climate variables for years corresponding to the upper and lower third of annual yield values for 13 of the variables is statistically significant at or above the 90% level. A correlation matrix was used to identify the variables that had the largest influence on annual yield. Four variables [called here critical climatic variables (CCV)], mean maximum August temperature, mean minimum February temperature, soil water surplus between April and September, and occurrence of autumn (fall) hurricanes, were built into a model to simulate adjusted yield values. The CCV model simulates the yield value with an rmse of 5.1 t ha−1. The mean of the adjusted yield data over the study period was 60.4 t ha−1, with values for the highest and lowest years being 73.1 and 50.6 t ha−1, respectively, and a standard deviation of 5.9 t ha−1. Presumably because of the almost constant high water table and soil water availability, higher precipitation totals, which are inversely related to radiation and temperature, tend to have a negative effect on the yields. Past trends in the values of critical climatic variables and general projections of future climate suggest that, with respect to the climatic environment and as long as land drainage is continued and maintained, future levels of sugarcane yield will rise in Louisiana.

Potential yield and water-use efficiency benefits in sorghum from limited maximum transpiration rate.

Limitations on maximum transpiration rates, which are commonly observed as midday stomatal closure, have been observed even under well-watered conditions. Such limitations may be caused by restricted hydraulic conductance in the plant or by limited supply of water to the plant from uptake by the roots. This behaviour would have the consequences of limiting photosynthetic rate, increasing transpiration efficiency, and conserving soil water. A key question is whether the conservation of water will be rewarded by sustained growth during seed fill and increased grain yield. This simulation analysis was undertaken to examine consequences on sorghum yield over several years when maximum transpiration rate was imposed in a model. Yields were simulated at four locations in the sorghum-growing area of Australia for 115 seasons at each location. Mean yield was increased slightly (5-7%) by setting maximum transpiration rate at 0.4 mm h-1. However, the yield increase was mainly in the dry, low-yielding years in which growers may be more economically vulnerable. In years with yield less than ∼450 g m-2, the maximum transpiration rate trait resulted in yield increases of 9-13%. At higher yield levels, decreased yields were simulated. The yield responses to restricted maximum transpiration rate were associated with an increase in efficiency of water use. This arose because transpiration was reduced at times of the day when atmospheric demand was greatest. Depending on the risk attitude of growers, incorporation of a maximum transpiration rate trait in sorghum cultivars could be desirable to increase yields in dry years and improve water use efficiency and crop yield stability.

Estimates of genetic parameters and expected genetic gains with selection in robust coffee

The present paper aimed to study the genetic variation of 15 half-sib progenies of robust coffea ( Coffea canephora Pierre). The trial was conducted at the Instituto Agronomico de Campinas (IAC/APTA) in a randomized complete block design with seven replications and one tree-plot. Annual and joint analyses of variance were obtained to estimate the genetic paramet ers for yield, in order to quantify the genetic gain from selection in eight production years. The genotypic variation coefficient s indicated expressive genetic variability for improvement of the yield. On account of the high variation in annual production, it is recommended that selection should be based on the general mean of the years. In low yield years, larger heritability values, coefficients of genetic variation, index of genotypic determination, and genetic gains were estimated.

Spatial and temporal patterns in Australian wheat yield and their relationship with ENSO

Spatial and temporal variability in wheat production in Australia is dominated by rainfall occurrence. The length of historical production records is inadequate, however, to analyse spatial and temporal patterns conclusively. In this study we used modelling and simulation to identify key spatial patterns in Australian wheat yield, identify groups of years in the historical record in which spatial patterns were similar, and examine association of those wheat yield year groups with indicators of the El Niño Southern Oscillation (ENSO). A simple stress index model was trained on 19 years of Australian Bureau of Statistics shire yield data (1975–93). The model was then used to simulate shire yield from 1901 to 1999 for all wheat-producing shires. Principal components analysis was used to determine the dominating spatial relationships in wheat yield among shires. Six major components of spatial variability were found. Five of these represented near spatially independent zones across the Australian wheatbelt that demonstrated coherent temporal (annual) variability in wheat yield. A second orthogonal component was required to explain the temporal variation in New South Wales. The principal component scores were used to identify high- and low-yielding years in each zone. Year type groupings identified in this way were tested for association with indicators of ENSO. Significant associations were found for all zones in the Australian wheatbelt. Associations were as strong or stronger when ENSO indicators preceding the wheat season (April–May phases of the Southern Oscillation Index) were used rather than indicators based on classification during the wheat season. Although this association suggests an obvious role for seasonal climate forecasting in national wheat crop forecasting, the discriminatory power of the ENSO indicators, although significant, was not strong. By examining the historical years forming the wheat yield analog sets within each zone, it may be possible to identify novel climate system or ocean–atmosphere features that may be causal and, hence, most useful in improving seasonal forecasting schemes.

Teleconnections between Pacific sea surface temperatures and Canadian prairie wheat yield

Relations between Pacific sea surface temperature (SST) and Canadian prairie wheat yield were investigated by correlation and by composites of SST during the nine lowest yield years, and the nine highest yield years. During winter, the SST anomalies (SSTA) in the North Pacific displayed a three-cell pattern of alternating negative–positive–negative–correlation with wheat yield, stretching diagonally from the Gulf of Alaska to the Philippine Sea. Major asymmetry between the SSTA composites for low yield years and those for high yield years implied a nonlinear relation between SSTA and wheat yield. As the composites for low yield years displayed much stronger SSTA than those for the high yield years, low yields seem more predictable than high yields. The composites also showed La Niña conditions in the equatorial region having a much more significant influence on Canadian wheat yield than El Niño conditions. A new teleconnection index was constructed from normalized SSTA. For March, this index had a correlation of 0.63 (and a Spearman rank correlation of 0.43) with the wheat yield during 1960–1997.

Thermal environment of cotton irrigated using canopy temperature

The threshold canopy temperature method for controlling a drip irrigation system includes a physiologically based threshold temperature and irrigation application rate that responds to the environment. Energy input from the environment causes canopy temperature to exceed the threshold value and irrigation is then applied. This study evaluated temperature distributions, amount of optimum time, and the amount of irrigation control time for cotton where irrigation scheduling was controlled by different threshold temperatures during the years 1988 to 1991. Optimum time for cotton growth was defined as the accumulated time that canopy temperatures were between 25 and 31 °C and the time accumulated above different threshold temperatures was designated as irrigation control time. Threshold temperatures over a 26 to 32 °C range altered the frequency distribution of temperature within the optimum temperature range (25–31 °C) by reducing temperatures above the threshold. Frequency of canopy temperatures of a 28 °C threshold temperature treatment decreased in the 28 to 29 °C increment and then remained below air temperature. Irrigation control time was more sensitive than optimum time to changes in threshold temperature between 26 and 31 °C. Optimum time and irrigation control time of the 28 °C threshold temperature varied by 37% and 29%, respectively. Lint yields in 1988 and 1990 were high while those in 1989 and 1991 were low because of unfavorable weather. Irrigation amounts applied during DOY 198–273 that were above 20 cm in high yield years or 12 cm in low yield years did not increase yield.

An Alternative Rationale for Corn Nitrogen Fertilizer Recommendations

Nitrogen recommendations based on corn (Zea mays L.) yield goal can overestimate N needs if yield expectations are not realistic, and yield goal-based N recommendations may not be well correlated with observed economic optimum N rates. This study investigated the feasibility of basing corn N recommendations on soil- and year-specific data rather than on yield goals. Soilspecific data from multiyear corn N rate studies, which included several soils and locations, were separated into high- and low-yielding groups based on each year's maximum yield. Based on a 24-yr corn N rate study on a Rozetta silt loam soil (finesilty, mixed, mesic Typic Hapludalfs) at Lancaster, WI, economic optimum N rates in high- and low-yielding years were nearly identical (160 to 170 Ib N/acre) [...]

Fluctuation in Yield and Chemical Composition of Rice Plant between High-yielding and Low-yielding Years

Fluctuation in Yield and Chemical Composition of Rice Plant between High-yielding and Low-yielding Years

てん菜の葉の損傷が根重、根中糖分におよぼす影響 : とくに多収年と低収年の違いについて

てん菜の葉の損傷が根重、根中糖分におよぼす影響 : とくに多収年と低収年の違いについて