• Authors:
    • Schimmelpfennig, D. E.
    • McCarl, B. A.
    • Chen, C. C.
  • Source: Climatic Change
  • Volume: 66
  • Issue: 1/2
  • Year: 2004
  • Summary: One of the issues with respect to climate change involves its influence on the distribution of future crop yields. Many studies have been done regarding the effect on the mean of such distributions but few have addressed the effect on variance. Furthermore, those that have been done generally report the variance from crop simulators, not from observations. This paper examines the potential effects of climate change on crop yield variance in the context of current observed yields and then extrapolates to the effects under projected climate change. In particular, maximum likelihood panel data estimates of the impacts of climate on year-to-year yield variability are constructed for the major U.S. agricultural crops. The panel data technique used embodies a variance estimate developed along the lines of the stochastic production function approach suggested by Just and Pope. The estimation results indicate that changes in climate modify crop yield levels and variances in a crop-specific fashion. For sorghum, rainfall and temperature increases are found to increase yield level and variability. On the other hand, precipitation and temperature are individually found to have opposite effects on corn yield levels and variability.
  • Authors:
    • Hrstkova, P.
    • Chloupek, O.
    • Schweigert, P.
  • Source: Field Crops Research
  • Volume: 85
  • Issue: 2-3
  • Year: 2004
  • Summary: Officially published data for the Czech Republic (CR) from 1920 to 2000 and for selected European countries (mostly from 1960 to 2000) were analysed. In the last 40 years, the yield of the five main crops was comparable with European Union (EU) for wheat, barley and rape, but lower for potato and sugar beet. The fastest yield growth was found for flax (2.15% per year), maize and wheat (1.61 and 1.53%), while growth was slower for hops and root crops and slowest for grassland hay (0.22%). The highest yield variation caused by individual years was for wine grapes (32.5%), poppy, edible legumes and flax (18.5-18.3%), while the lowest level of variation was for cereals, i.e. oats, barley, wheat, rye and hay from arable land (9.7-12.0%). For many crops, yield variation decreased over time. The most adaptable crops, whose yield increased most in fertile years, were flax, wheat, edible legumes, maize, rape and barley (regression coefficient of 1.76-1.24), while the lowest level of adaptability was shown by hops, sugar beet, hay from grassland and poppy (0.68-0.14). The higher the level of adaptability the higher the yield growth over the 75 years analysed. The differences in yield of the most commonly grown crops between the EU and the CR can be explained by the different levels of adaptability of the crops in the two regions. Of the five most commonly grown CR crops, wheat was the most adapted crop in 7 of the 10 European countries studied (without regard to other countries), and sugar beet was the least adapted in 6 countries, Within the 10 countries analysed (without regard for the adaptability of the crop in particular countries) wheat, rape and sugar beet were most adaptable in Spain; barley was most adaptable in Italy; and potato was most adaptable in Hungary. The crops in other countries showed more stability across years. Yields of these five crops in the 10 countries were correlated to each other, with only the yield of potato and sugar beet in the former Soviet Union and that of rape in United Kingdom not being influenced by general factors affecting other countries. The higher the yield of sugar beet in a country of the 10 evaluated, the higher was its adaptability in that country (r = 0.717*). Crop diversity in the CR decreased significantly over the period. Each year the percentage of the three most commonly grown crops increased by 0.41% (percentage of the five most commonly grown crops by 0.14%). The percentage of particular cereals on arable land (wheat 23.0%, barley 17.1%, rye 5.1%, oat 5.2%) and their yields were related to their response to fertilisation over the last 40 years. The average temperature increased significantly during the last 50 years, on average by 0.021 degreesC each year, but in the last 10 years by 0.087 degreesC each year. These climate changes were favourable for the most of the commonly grown crops (wheat, barley, rape, sugar beet, rye, maize and legumes), since the crops gave higher yields in warmer years that were accompanied by more hours of sunshine. The other crops were indifferent to climate changes. Fertilisers have been used in the CR to a greater extent since 1946/1947 (22 kg of nutrients per hectare) with maximum usage in 1985/1986 (273 kg ha(-1), including 105 kg N, 86 kg P and 82 kg K). The consumption rate of nutrients increased by 2.91 kg ha(-1) annually from 1918 to 2000, as found by the regression coefficient. One kilogram of nutrients (N + P + K) increased yields of cereals by 6.7-10.1 kg ha(-1) of grain, rape by 5.2, root crops by 26.1-37.8, hops and wine grapes by 2.0-2.6 kg ha(-1). Yield growth due to fertilisation varied from 9.1% (hay from arable land) up to 84.1% (hops) of the entire growth (=100%). The percentage in grain crops (cereals, grain legumes and rape) was 54.3 (maize)-69.8% (barley), and 63.3% on average in the eight crops. It was also similar in root crops, but only 13.4% for wine grape yields. The highest yield growth per 1 kg of nutrients from fertilisers was found in wheat, rape, sugar beet and potato at the level of application of 70-120 kg ha(-1) nutrients. The efficiency of applied nutrients was higher in years with average precipitation than in years with over-average precipitation, and much higher than in dry years. The yield growth for 1 kg nutrients in all grain crops was lowest in years with average temperature, and highest in most of the crops in years with low mean annual temperature. The estimated balance of nitrogen (applied nitrogen in fertilisers minus nitrogen utilised in harvested crops) was negative during 1947-1960, positive during 1970-1990, and slightly negative again from 1995 to 2000. The surplus of applied mineral nitrogen reached in the years of positive balance was 18.5-36.8 kg ha(-1). The impact of the weather was less than the influence of fertilisation. The dynamics of yield in Germany was studied by multiple regression analysis from 1946 to 1999. The annual increase of wheat yield was 50 kg ha(-1), and per kilogram of N-fertiliser by 10 kg ha(-1). The increase per year in the multiple regression was only 73% of the increase in the simple regression. Therefore, 27% of the increase was related to N-fertilisation (and also to other inputs). The corresponding figures were 25% for rye, 30% for rape, 36% for oats, 47% for potato and 66% for flax. No significant influence of N-fertiliser could be found for other crops. It is concluded that those crops exhibiting the highest increase in yield in the CR over the 75 years investigated were also the most adaptable to inter-annual variability in weather, cultivars grown and to cultivation technologies used. The least adapted crop across 10 European countries was sugar beet, for which adaptability was correlated to yield in the particular country. Among the factors studied, the high response to fertilisation was an important factor in the adaptability of particular crops over the 75 years studied. The adaptability of crops to inter-annual variation is therefore a very important trait for consideration by plant breeders. (C) 2003 Elsevier B.V. All rights reserved.
  • Authors:
    • Yang, H.
    • Walters, D. T.
    • Dobermann, A.
    • Cassman, K. G.
  • Source: Annual Review of Environment and Resources
  • Volume: 28
  • Issue: 1
  • Year: 2003
  • Summary: Agriculture is a resource-intensive enterprise. The manner in which food production systems utilize resources has a large influence on environmental quality. To evaluate prospects for conserving natural resources while meeting increased demand for cereals, we interpret recent trends and future trajectories in crop yields, land and nitrogen fertilizer use, carbon sequestration, and greenhouse gas emissions to identify key issues and challenges. Based on this assessment, we conclude that avoiding expansion of cultivation into natural ecosystems, increased nitrogen use efficiency, and improved soil quality are pivotal components of a sustainable agriculture that meets human needs and protects natural resources. To achieve this outcome will depend on raising the yield potential and closing existing yield gaps of the major cereal crops to avoid yield stagnation in some of the world's most productive systems. Recent trends suggest, however, that increasing crop yield potential is a formidable scientific challenge that has proven to be an elusive goal.
  • Authors:
    • Thottappilly, G.
    • Loebenstein, G.
  • Source: Virus and virus-like diseases of major crops in developing countries
  • Issue: xlvii + 800 pp
  • Year: 2003
  • Summary: This book is a comprehensive up-to-date treatise on virus and virus-like diseases of the major crops (cassava, potatoes, sweet potato, yam, rice, maize, sorghum, other cereal crops, cowpea, soyabean, groundnut, common bean, other legumes, banana, pawpaw, cocoa, sugarcane, coconut, palm trees, citrus, tomato, cucurbits, other vegetables, cotton, sunflower and spices) in developing countries and their detection, isolation, biological and molecular characterization, transmission and possible approaches for their control. Also included are chapters on the general impact of these diseases, epidemiology, quarantine and technology transfer.
  • Authors:
    • Kasha, K. J.
    • Maluszynski, M.
    • Forster, B. P.
    • Szarejko, I.
  • Source: Doubled haploid production in crop plants: a manual
  • Year: 2003
  • Summary: This manual presents a set of protocols for the production of doubled haploid plants in 22 major crops species including 4 tree species, and includes protocols from different germplasm of the same species. The crops covered include barley, wheat, maize, rice, triticale, rye, oats, durum wheat, timothy grass ( Phleum pratense), ryegrass ( Lolium), rape, broccoli, tobacco, potato, flax/linseed, sugarbeet, asparagus, onion, apple, poplar, cork oak ( Quercus suber), and citrus. All steps of doubled haploid production are detailed from donor plant growth conditions, through in vitro procedures, media composition and preparation, to regeneration of haploid plants and chromosome doubling methods. The practical protocols are supplemented with a list of published protocols for other crop plants, and separate chapters deal with major application of doubled haploids in breeding, mutant production, transgenesis, genetic mapping and genomics.
  • Authors:
    • Beghin, J. C.
    • Fang, C.
  • Source: Agricultural trade and policy in China: issues, analysis and implications
  • Year: 2003
  • Summary: This chapter assesses the protection and comparative advantage of China's major agricultural crops in six regions, using a modified Policy Analysis Matrix and 1997-2000 data. The following commodities are considered: early indica rice, late indica rice, japonica rice, wheat, maize, sorghum, soyabean, rapeseed, cotton, tobacco, sugarcane, and a subset of fruits and vegetables. The results suggest that, with the exception of high quality rice, the production of grains and oilseeds tends to suffer from a lack of comparative advantage over other crops in China, such as fruit and vegetables, tobacco and cotton. Further, it is concluded that grain self-sufficiency policies reduce allocative efficiency several-fold.
  • Authors:
    • Sukhochev, V. N.
    • Gurin, A. G.
  • Source: Sadovodstvo i Vinogradarstvo
  • Issue: 2
  • Year: 2003
  • Summary: In research during 1997-2000 at the All-Russian Institute of Fruit Crop Breeding in Orel province, Russia, the use of field crops sown between strawberry rows was investigated as a means of suppressing weed growth. Oats, barley, rape and mustard were sown between rows of strawberry cv. Red Gauntlet; the sowing date was manipulated so that the field crops would be cut down after strawberry harvest but before they could set seed. In terms of the number of plants of the major weed species present at the end of vegetative growth, there were 122 plants per linear m in the untreated control, but only 37 in the barley, 48 in the oats, 53 in the mustard and 60 in the rape treatments. The cereals were better at suppressing weeds because they were sown earlier than the crucifers. In terms of annual strawberry fruit yield, the average for the 4 years of the trial was 8.07 t/ha in the control but higher with the weed suppressing crops: 8.18, 8.49, 8.62 and 8.66 for the rape, mustard, oats and barley treatments, respectively.
  • Authors:
    • Lokaj, G. R. W.
    • Majek, B. A.
    • Belding, R. D.
    • Hammerstedt, J.
    • Ayeni, A. O.
  • Source: HortTechnology
  • Volume: 13
  • Issue: 2
  • Year: 2003
  • Summary: Peach ( Prunus persica cv. Candor) trees were established and grown from 1996 to 1999 at the Rutgers Agricultural Research and Extension Center, Bridgeton, New Jersey, USA, to compare their performance under four methods of orchard floor preparation: flat no-till, flat cultivated, mound unmulched, and mound mulched orchard floors. The experimental site was flat and the soil was a well-drained Aura gravelly sandy loam (61% sand, 31% silt and 8% clay) with a pH of 6.5, cation exchange capacity of 5.7, and organic matter content of 2.0%. Soil moisture holding capacity and gas exchange capacity determine the efficacy of mounding in peach orchards. Under these conditions, the method of orchard floor preparation had no effect on peach tree trunk cross-sectional area, fruit number per tree, fruit size and yield. Thus, without irrigation, there was no advantage to the early performance of peach trees associated with orchard floor mounding on Aura gravelly sandy loam when situated on a flat terrain.
  • Authors:
    • Morse, R. D.
    • Miyao, E. M.
    • Temple, S. R.
    • Lanini, W. T.
    • Mitchell, J. P.
    • Herrero, E. V.
    • Campiglia, E.
  • Source: California Agriculture
  • Volume: 55
  • Issue: 1
  • Year: 2001
  • Summary: The efficacy of no-till systems in conserving soil moisture and improving water infiltration under furrow irrigation was evaluated during 1997 and 1998 in California, USA. Two grass/legume mixtures, i.e. triticale/lana woolypod vetch (* Triticosecale/ Vicia dasycarpa [ V. villosa]) and rye/lana woolypod vetch ( Secale cereale/ V. dasycarpa), were used as cover cop mulches in no-till treatments, and compared with a winter fallow treatment with pre-plant herbicide (fallow +h) and a fallow control treatment with no herbicide (fallow -h). Tomato cv. Halley 3155 plants were transplanted in April 1997 and 1998, sprinkle irrigated during the first 6 weeks after transplanting, and furrow irrigated thereafter until 3 weeks before harvest. During 1997, soil water content between 0 and 78 inches did not differ among treatments, while soil water content during the 1997/98 winter was higher under the fallow +h than the cover crop treatments until cover crop termination. Soil water content of cover crop treatments in shallower soil layers (18 and 42 inches) was significantly lower than fallow treatments at the end of the winter. During the 1998 tomato crop season, soil water content between 0 and 90 inches was greater under the triticale and rye mulches than the fallow +h, beginning the 3rd week after furrow irrigations were started. Soil moisture in the shallower layers was also affected by cover crop mulches. In the 42-inch depth increment, there was significantly higher water content under the cover crops than under the fallow +h from about 1 month after the first furrow irrigation until 2 weeks before the last irrigation. Changes in soil water content during furrow irrigation under the fallow +h treatment appeared to be more pronounced than under the triticale or rye surface mulches. Soil compaction in the fallow +h treatment was higher than under the cover crop mulches for most of the 0.6-inch intervals, especially below 1 foot, but differences were significantly higher only for the 3, 3.6, 4.2, 17, 18, and 24-inch depth, but lower from the surface to 2.4 inches. Soil carbon was significantly higher (by 14 and 18%) under triticale and rye, respectively, compared with the fallow +h treatment. The number of earthworms was also higher in no-till (2.1 earthworms per square foot) than in the fallow treatments (0.6 earthworms). Tomato canopy growth did not reach 100% cover in either 1997 or 1998, while tomato plant growth, assessed by measuring the photosynthetically active radiation intercepted by the canopy, did not differ in the triticale, rye, and fallow +h system in either 1997 or 1998. Results showed that the no-till mulch system enhanced water infiltration and soil water conservation.
  • Authors:
    • Morse, R. D.
    • Miyao, E. M.
    • Temple, S. R.
    • Lanini, W. T.
    • Mitchell, J. P.
    • Herrero, E. V.
    • Campiglia, E.
  • Source: HortTechnology
  • Volume: 11
  • Issue: 1
  • Year: 2001
  • Summary: No-tillage processing tomato production in four winter cover crop-derived mulches was evaluated in 1997 and 1998 in Five Points, California, USA. The effectiveness of two medics, 'Sava' snail medic ( Medicago scutellata), and 'Sephi' barrel medic ( Medicago truncatula), and two cereal/legume cover crop mixtures, triticale/'Lana' woolypod vetch ( Triticum x Secale/ Vicia dasycarpa [ Vicia villosa]) and rye/'Lana' woolypod vetch ( Secale cereale/ V. dasycarpa), was compared with two conventionally tilled fallow controls (with and without herbicide) (fallow+h and fallow-h) in suppressing weeds and maintaining yields with reduced fertilizer inputs. The comparison was conducted as a split plot, with three N fertilization rates (0, 100, and 200 lb/acre; 0, 112, and 224 kg/ha) as main plots and cover crops and fallow controls as subplots. Tomato seedlings were transplanted 3 weeks after the cover crops had been mowed and sprayed with herbicide. There were no significant differences in weed cover in the no-till cover crop treatments relative to the fallow controls in 1997. Early season weed suppression in rye/vetch and triticale/vetch plots was similar to herbicide-treated fallow (fallow+h) in 1998, however, later in the 1998 season weed suppression was best in the fallow+h. Tissue N was highest in the fallow treatments in both 1997 and 1998. Yields were highest in the triticale/vetch and fallow and lowest in sephi treatments in 1997, but there were no differences among treatments in 1998.