Does pollarding trees improve the crop yield in a mature alley-cropping agroforestry system?

In agroforestry systems, the canopy of maturing trees progressively reduces the radiation available for the crop. Tree management practices such as pollarding can be used to restore the crop light availability. We monitored durum wheat, barley and pea yields during three consecutive years in an alley-cropping agroforestry system with hybrid walnut trees in Southern France. Trees have been pruned regularly to 4 m since planting (in 1995), and a section of 50 trees was pollarded at 4 m height for the first time in 2013. We measured the yields and yields components in the two different tree management systems and in a sole crop control. The non-pollarded trees reduced significantly the incident light (around 80% of the global radiation left in average) and both wheat (68% of the control) and pea (69% of the control), but not barley mean yields. In pollards inter-row, the average incident light was 98% of the total radiation the first year and the wheat yield 89% of the control. But 3 years after pollarding, the incident light was 79% of the total radiation and the pea yield was only 67% of the control. Pollarding had a transient positive impact on crop yield; after 3 years, pollards were more competitive for light than control trees. Pollarding may also reduce the belowground trees competition, but slightly, as the crop vegetative growth occurs when the trees are leafless.     

Sulphur in crop production — invited paper

The fact that crop deficiencies of sulpher (S) have been reported with increasing frequency over the past several years greater attention has been focused on the importance of this element in plant nutrition. In many regions in the world S deficiency has been recognized as a limiting factor for crop production. Especially in Western Europe incidence of S deficiency has increasingly reported in Brassica over the last decade. While sulphate in soil is a direct S source for plants, generally more than 95% of soil S is organic bonded and divided into sulphate ester S and carbon-bonded S. Although not readily plant available, organic S compounds may potentially contribute to the S supply of plants via mineralization. While sulphate esters play an important role in the short term release of sulphate, carbon-bonded S seems to be responsible for long-term mineralization. Predicting the S requirement of plants has become increasingly importance in European agriculture. To predict S delivery of soils different soil testing methods are suggested, which take the most important soil characteristics into consideration. It is suggested to elaborate a sulphur test in field experiments with the most sensitive crop in rotation, like oilseed rape. Besides soil test tissue analysis assist in identifying S deficiencies. However, in general they are used very seldom for making fertilizer S recommendations. To achieve high yields and to minimize S leaching, rates of fertilizer S should be recommended on the basis of available soil S and crop requirement.     

Does the recoupling of dairy and crop production via cooperation between farms generate environmental benefits? A case-study approach in Europe

The intensification of agriculture in Europe has contributed significantly to the decline of mixed crop-livestock farms in favour of specialised farms. Specialisation, when accompanied by intensive farming practices, leaves farms poorly equipped to sustainably manage by-products of production, capture beneficial ecological interactions, and adapt in a volatile economic climate. An often proposed solution to overcome these environmental and economic constraints is to recouple crop and livestock production via cooperation between specialised farms. If well-managed, synergies between crop and livestock production beyond farm level have the potential to improve feed and fertiliser autonomy, and pest regulation. However, strategies currently used by farmers to recouple dairy livestock and crop production are poorly documented; there is a need to better assess these strategies using empirical farm data. In this paper, we employed farm surveys to describe, analyse and assess the following strategies: (1) Local exchange of materials among dairy and arable farms; (2) Land renting between dairy and arable farms; (3) Animal exchanges between lowland and mountainous areas; and (4) Industrially mediated transfers of dehydrated fodder. For each strategy, cooperating farm groups were compared to non-cooperating farm groups using indicators of metabolic performance (input autonomy, nutrient cycling and use efficiency), and ecosystem services provision. The results indicate that recoupling of crop and dairy production through farm cooperation gives farmers access to otherwise inaccessible or underutilised local resources such as land, labour, livestock feed or organic nutrients. This in turn leads to additional outlets for by-products (e.g. animal manure). Farmers’ decisions about how to allocate the additional resources accessed via cooperation essentially determine if the farm diversifies, intensifies or expands operations. The key finding is that in three of the four crop-livestock integration strategies assessed, these newly accessed resources facilitated more intensive farming practices (e.g. higher stocking rate or number of milking cows per hectare) on cooperating dairy farms relative to non-cooperating, specialised dairy farms. As a consequence, cooperation was accompanied by limited environmental benefits but helped to improve resource use efficiency per unit of agricultural product produced. This article provides a critical step toward understanding real-world results of crop-livestock cooperation beyond the farm level relative to within-farm crop-livestock integration. As such, it brings practical knowledge of vital importance for policy making to promote sustainable farming.     

Has yield stability changed with genetic improvement of wheat yield?

The effect of plant breeding on yield and their physiological determinants has been widely studied in wheat. However, it is poorly understood how, and to what extent, yield stability has been modified. To attempt a direct analysis of changes in absolute and relative yield stability, data of yield of cultivars released in different eras in different environments were obtained from records from our lab and from the literature. Depending on the availability of data, effects of plant breeding on yield stability of cultivars released in Argentina, Australia, Italy and the United Kingdom were evaluated using a quantitative approach. In this paper it was assumed that the slope of yield vs. environmental index estimates the instability of the cultivars. In addition, a more qualitative approach for Mexico, and the former USSR complemented this analysis. There was a clear decrease in yield stability assessed in absolute terms as a consequence of wheat breeding. In Argentina, Australia, Italy and the UK this decrease was related to the magnitude of yield increases. However, the decrease in yield stability in Argentina and Australia was less than for Italy and the UK, particularly so during the last 30 years. Modern cultivars released in Argentina and Australia showed a trend to maintain yield stability as a percentage of their yield similar to that of their predecessors, while the two European countries analysed tended to a slight decrease in yield stability even in relative terms. The complementary, less quantitative evaluation of Mexico and the former USSR appeared to confirm the quantitative trends described for the other countries, i.e. a general decrease in yield stability (assessed in absolute terms) with genetic gains in yield potential. This revised version was published online in July 2006 with corrections to the Cover Date.     

Yield and yield components of wheat and maize in wheat–maize intercropping in the Netherlands

Intercropping is widely used by smallholder farmers in developing countries, and attracting attention in the context of ecological intensification of agriculture in developed countries. There is little experience with intercropping of food crops in Western Europe. Yields in intercrops depend on planting patterns of the mixed species in interaction with local growing conditions. Here we present data of two years field experimentation on yield and yield components of a wheat–maize intercrop system in different planting configurations in the Netherlands. Treatments included sole crops of wheat (SW) and maize (SM), a replacement intercrop consisting of strips of six wheat rows alternating with two maize rows (6:2WM), as well as subtractive or additive designs, based on skip-row (6:0WM, 0:2WM) and add-row (8:2WM, 6:3WM) configurations. The land equivalent ratio (LER) of intercrops varied from 1.18 to 1.30 in 2013 and from 0.97 to 1.08 in 2014. Wheat grown in the border rows of wheat strips had higher ear number per meter row, greater kernel number per ear, and greater yield per meter row than wheat in inner rows and sole wheat, indicating reduced competition. Wheat in the border rows in the intercrops had, however, reduced thousand kernel weight and harvest index, indicating that competition in border rows intensified over time. Intercropping negatively affected maize biomass and thousand kernel weight, especially in add-row treatments. This study indicates that there is a potential yield benefit for the wheat–maize intercropping system under Western European growing conditions. However, the LER was affected by yearly variation in weather conditions and significantly greater than one in only one of the two years of the study.     

Dry matter yield,nitrogen content,and competition in pea–cereal intercropping systems

Intercrops of pea (Pisum arvense L.), a popular legume used in intercropping systems with winter cereals for forage and silage production, with wheat (Triticum aestivum L.), rye (Secale cereale L.), and triticale (× Triticosecale Wittmack) in two seeding ratios (60:40 and 80:20) were compared with monocrops of pea and cereals for two growing seasons. Growth rate, dry matter yield, and N uptake were determined in each intercropping system. Furthermore, several indices were used to evaluate the intercropping systems and analyze the competition and the interrelationships between mixture components. Growth rate of cereals was lower in the mixtures than in the monocrops. Dry matter yield was higher in triticale monocrop, followed by its two intercrops, and the pea–wheat 80:20 intercrop. Moreover, triticale monocrop, pea–triticale intercrops, and pea–wheat 80:20 intercrop showed the highest crude protein yield and N uptake. The land equivalent ratio (LER), relative crowding coefficient (K), actual yield loss (AYL), and system productivity index (SPI) values were greater for the pea–triticale mixtures and the pea–wheat and pea–rye mixtures (80:20), indicating an advantage of intercropping. In most intercrops, the values of partial K, AYL, aggressivity, and competitive ratio (CR) indicated that the cereal was more competitive than pea. The highest values of monetary advantage index (MAI) and intercropping advantage (IA) were recorded for the pea–triticale and the pea–wheat mixtures (80:20). Overall, pea–triticale and pea–wheat mixtures (80:20) were more productive and produced better forage quality than the other mixtures and thus could be adopted by the farmers as alternative options for forage production.     

Identifying the impact of multi-hazards on crop yield—A case for heat stress and dry stress on winter wheat yield in northern China

Winter wheat production in northern China severely suffered from high temperatures and low relative humidity. However, the spatio-temporal pattern of heat stress and dry stress and the impacts of these multi-hazards on winter wheat yield have rarely been investigated. Using historical climate data, phenology data and yield records from 1980 to 2008, an analysis was performed to characterize the spatio-temporal variability of heat stress and dry stress in the post-heading stages of wheat growth in northern China. Additionally, these stresses’ impacts on winter wheat yield fluctuations were evaluated. Spatially, the central and northern parts of northern China have seen more serious heat stress, while greater dry stress has been observed in the northwest and north of the research area. Temporally, the heat stress has increased in the western part but decreased in the central and eastern parts of research area. Dry stress has aggravated in the entire northern China during the past decades, indicating the complexity of the exposure to adverse climate conditions. These two hazards (heat stress and dry stress) have contributed significant yield loss (up to 1.28% yield yr⁻¹) in most parts of the research region. The yield in the west was more sensitive to heat stress, and dry stress was the main hazard in the south. Additionally, the opposite spatial pattern between the sensitivity and exposure revealed that the climate is not the only factor controlling the yield fluctuation, the local adaptation measures used to mitigate negative influences of extreme events should not be ignored. In general, this study highlighted a focus on the impacts of multi-hazards on agricultural production, and an equal importance of considering local adaptation ability during the evaluation of agricultural risk in the future. Additionally, paying more attention to higher sensitive areas and to more reasonable and practical adaptive strategies is critical and significant for food supply security.     

Crop and cattle production responses to tillage and cover crop management in an integrated crop–livestock system in the southeastern USA

Integrated crop–livestock systems can help achieve greater environmental quality from disparate crop and livestock systems by recycling nutrients and taking advantage of synergies between systems. We investigated crop and animal production responses in integrated crop–livestock systems with two types of winter cover cropping (legume-derived N and inorganic fertilizer N), two types of tillage [conventional disk (CT) and no tillage (NT)], and whether cover crops were grazed by cow/calf pairs or not. The 13-ha field study was a modification of a previous factorial experiment with four replications on Ultisols in Georgia, USA. Recurring summer drought severely limited corn and soybean production during all three years. Type of cover crop had little influence and grazing of cover crops had minor influence on crop production characteristics. Cattle gain from grazing of winter cover crops added a stable component to production. No-tillage management had large positive effects on corn grain (95 vs. 252 g m⁻² under CT and NT, respectively) and stover (305 vs. 385 g m⁻²) production, as well as on soybean grain (147 vs. 219 g m⁻²) and stover (253 vs. 375 g m⁻²) production, but little overall effect on winter wheat grain (292 g m⁻²) and stover (401 g m⁻²) production. Our results suggest that robust, diversified crop–livestock systems can be developed for impoverished soils of the southeastern USA, especially when managed under no tillage to control environmental quality and improve resistance of crops to drought.     

Genotype × environment interaction and genetic improvement for yield and yield stability of rainfed durum wheat in Iran

The genotype × environment (GE) interaction influences genotype selection and recommendations. Consequently, the objectives of genetic improvement should include obtaining genotypes with high potential yield and stability in unpredictable conditions. The GE interaction and genetic improvement for grain yield and yield stability was studied for 11 durum breeding lines, selected from Iran/ICARDA joint program, and compared to current checks (i.e., one durum modern cultivar and two durum and bread wheat landraces). The genotypes were grown in three rainfed research stations, representative of major rainfed durum wheat-growing areas, during 2005–09 cropping seasons in Iran. The additive main effect and multiplicative interaction (AMMI) analysis, genotype plus GE (GGE) biplot analysis, joint regression analysis (JRA) (b and S²di), six stability parameters derived from AMMI model, two Kang’s parameters [i.e., yield-stability (YSi) statistic and rank-sum], GGE distance (mean performance + stability evaluation), and two adaptability parameters [i.e., TOP (proportion of environments in which a genotype ranked in the top third) and percentage of adaptability (Ad)] were used to analyze GE interaction in rainfed durum multi-environment trials data. The main objectives were to (i) evaluate changes in adaptation and yield stability of the durum breeding lines compared to modern cultivar and landraces (ii) document genetic improvement in grain yield and analyze associated changes in yield stability of breeding lines compared to checks and (iii) to analyze rank correlation among GGE biplot, AMMI analysis and JRA in ranking of genotypes for yield, stability and yield-stability. The results showed that the effects due to environments, genotypes and GE interaction were significant (P < 0.01), suggesting differential responses of the genotypes and the need for stability analysis. The overall yield was 2,270 kg ha^?1 for breeding lines and modern cultivar versus 2,041 kg ha^?1 for landraces representing 11.2 % increase in yield. Positive genetic gains for grain yield in warm and moderate locations compared to cold location suggests continuing the evaluation of the breeding material in warm and moderate conditions. According to Spearman’s rank correlation analysis, two types of associations were found between the stability parameters: the first type included the AMMI stability parameters and joint regression parameters which were related to static stability and ranked the genotypes in similar fashion, whereas the second type consisted of the rank-sum, YSi, TOP, Ad and GGED which are related to dynamic concept of stability. Rank correlations among statistical methods for: (i) stability ranged between 0.27 and 0.97 (P < 0.01), was the least between AMMI and GGE biplot, and highest for AMMI and JRA and (ii) yield-stability varied from 0.22 (between GGE and JRA) to 0.44 (between JRA and AMMI). Breeding lines G8 (Stj3//Bcr/Lks4), G10 (Ossl-1/Stj-5) and G12 (modern cultivar) were the best genotypes in terms of both nominal yield and stability, indicating that selecting for improved yield potential may increase yield in a wide range of environments. The increase in adaptation, yield potential and stability of breeding lines has been reached due to gradual accumulation of favorable genes through targeted crosses, robust shuttle breeding and multi-locational testing.     

Agronomic management options to enhance adoption of maize–common bean–common bean sequential intercropping in southern Ethiopia

Journal of Crop Science and Biotechnology - Achieving food security is a prime strategic goal for many developing countries where subsistence smallholder farming is dominant. It is crucial to study...     

The introduction of oil palm in Northeast Thailand: A new cash crop for smallholders?

As part of the Thai Government's objective to increase energy security through biodiesel, oil palm was introduced to Northeast Thailand in 2005. Nong Khai Province was selected as a pilot project because of its suitable environmental conditions. This study assesses the acceptance of policy interventions and socio‐economic conditions by adopters and non‐adopters. We found that total farmland size was significantly higher among oil palm producers than among non‐producers. Nevertheless, the area under oil palm cultivation did not increase in accordance with land size in the way rubber did. Oil palm and non‐oil palm farmers had almost equal amounts of rice area thereby providing household food security. Oil palm did not replace food crops. Farmers investing in oil palm tend to base their livelihood around on‐farm production, whereas non‐adopters tend to diversify with off‐farm income sources. Oil palm was found to be one component of a diversified farming system and an additional income source, albeit not the primary one. In conclusion, oil palm was a crop that had been tried by (wealthier) farmers with sufficient capital, and an aim to further diversify on‐farm household income. Oil palm is certainly not (yet) contributing substantially to household income in Thailand's Northeast.     

Exploring genotype × environment interaction in Robusta coffee for growth and yield stability under tropical environments

Journal of Crop Science and Biotechnology - Agronomic performance of Robusta coffee (Coffea canephora) is affected by genotype by environment interaction, which demands multi-environment testing of...     

Responses of soil properties,root growth and crop yield to tillage and crop residue management in a wheat–maize cropping system on the North China Plain

Crop residue removal and subsoil compaction are limiting to yield improvement in the North China Plain (NCP). We conducted a field study composed of six consecutive crop growing seasons from 2010 to 2013 in Henan province, China, to determine responses of soil properties, crop root distribution and crop yield to tillage and residue management in a wheat–maize cropping system under irrigated conditions. Tillage practices comprised mouldboard ploughing (MP) to a depth of 15-cm, deep mouldboard ploughing (DMP) to a depth of 30-cm, and chisel ploughing (CP) to a depth of 30-cm. Crop residue management included crop residue retained (CRRet) and crop residue removed (CRRem). The results indicated that yields in DMP and CP increased by 6.0% and 7.3% for wheat and by 8.7% and 9.0% for maize, respectively, relative to MP. The CRRet treatment also increased wheat yield by 6.7% and maize yield by 5.0%. The yield increases under DMP and CP were related to reduced bulk density and soil penetration resistance, increased soil water content, improved total N distribution and improved root density (0–60-cm). Compared with MP, the root mass density under DMP and CP were increased by 43.4% and 42.0% for wheat and by 40.6% and 39.4% for maize, respectively. The yield increases under CRRet were also related to increased soil water content, reduced penetration resistance and increased N status (0–40-cm). Overall, for DMP + CRRet and CP + CRRet, a more favorable soil environment alongside greater root mass density and suitable spatial distribution resulted in higher grain yields of wheat and maize. Thus, compared with conventional shallow tillage practice, DMP or CP with residue application could improve soil quality and agricultural productivity under irrigated areas with loam soil in the NCP.     

Genotype × environment interaction and yield stability in barley (Hordeum vulgare L.) genotypes in the central highland of Ethiopia

Journal of Crop Science and Biotechnology - Barley is one of the most important cereal crops cultivated over a wider environment in the diverse agro-ecologies in Ethiopia. Study on genotype by...     

Poverty in Canada: Does Manufacturing Matter?

We focus our research on this question: Does an expansion in the percentage of labour employed in the manufacturing sector lead to reductions in the poverty rate? While some research suggests that regional differences in the employment share of the manufacturing sector explain variation in poverty rates, we do not find empirical evidence of this poverty‐ameliorating effect in our regression analysis of Canadian Census Districts between the years 2001 and 2006.     

Importance of growth characteristics for yield of barley in different growing systems: will growth characteristics describe yield differently in different growing systems?

The interest in organic grown cereals has increased the need for variety tests under organic growing systems and/or the knowledge on whether growth characteristics describe yield differently under conventional and organic conditions. This paper is a contribution to that question by examining the relationships between some important growth characteristics in barley trials in both systems in Northern Sweden and in Denmark. Mixed model analyses were used for regressions of growth characteristics (or transformations of those) on yield (and log-transformed yield), allowing the slope to depend on the growing system. The analyses showed that diseases seemed to have a less negative effect on yield in the organic growing system than in the conventional growing system if pesticides were not applied. For other characteristics the effect depended on the country. This was the case for grain characteristics where the effect of volume weight in the Swedish trials was much larger in the conventional growing system than in the organic growing system, while a non-significant difference in the opposite direction was found for the trails from Denmark. For the trials from Denmark the effect of grain weight was much larger in the organic growing system than in the conventional growing system, but there was only a small and non-significant difference in the Swedish trials. In both countries there was a significant interaction between the two grain characteristics.     

Should crop scientists consider a journal's impact factor in deciding where to publish?

To publish papers that have impact is indispensable for good scientists. It is frequently accepted that the impact factor (IF) of a journal reflects the likelihood of a paper to have impact. Many scientists may then attempt publishing their papers in journals with the highest possible IF. This is relevant for crop scientists as in many cases our hypotheses may be relevant to agronomy/agriculture but the product of our work may be published in the more basic plant science journals, which in general have higher IF than agronomic journals. To test whether agronomic journals may be better vehicles than plant science journals for crop physiological work, I did an analysis of my own publications (only “standard” papers, disregarding reviews) relating their annual citation rates against the IF of the journal in which they were published. The relationship was virtually inexistent, and my most frequently quoted papers were published in agronomic rather than in plant sciences journals. Conversely, restricting the analysis to the papers published within agronomic journals there was a relationship between the record of citations of the papers and the IF of the journals, particularly if the analysis is restricted to the most quoted papers in each journal. I then analyzed the cases of three other well-recognized crop scientists, to check whether the findings with my results were exceptional, and in the three cases results were remarkably similar. Therefore, it seems that the journal IF might be a valuable criterion for choosing the best journal in which to publish our best contributions only when comparing within agronomic journals, but not within combinations of agronomy and plant science journals. This should be also taken into account in evaluation processes when comparing scientists working in related but not identical fields.     

An approach to understanding persistent yield variation—A case study in North China Plain

Large gaps between maize yields on average farmers’ fields and the highest yields achieved by either experiment or farmers are typical throughout the developing world, including in the North China Plain (NCP). Understanding the underlying causes to this yield gap is important for prioritizing strategies for shrinking this gap and improving food security. Quzhou county in Hebei province is typical of the winter-wheat summer-maize system in NCP where the average plot size is only 0.25 ha. To analyze this cropping system amidst the challenge of substantial heterogeneity, we identified fields that were either persistently higher or lower yielding according to remote sensing yield estimates, and then conducted detailed field surveys. We found irrigation facility to be a major constraint to yield both in terms of irrigation water quality and farmers’ access to wells. In total, improving the access to unsalty water would be associated with a 0.32 t/ha (4.2%) increase in multi-year average yield. In addition, farmers’ method of choosing cultivar, which likely relates to their overall knowledge level, significantly explained yield variation. In particular, those choosing cultivars according to technician advice, personal experiences and high yielding neighbors’ advice had on average higher yield than farmers that either followed seed sellers’ advice or collectively purchased seeds.     

Utilization of alien genes to enhance Fusarium head blight resistance in wheat – A review

Fusarium head blight (FHB) is a destructive disease of wheat worldwide. Sources of resistance to FHB are limited in wheat. Search for novel sources of effective resistance to this disease has been an urgent need in wheat breeding. Fusarium head blight resistance has been identified in relatives of wheat. Alien chromatin carrying FHB resistance genes has been incorporated into wheat through chromosome addition, substitution, and translocation. Relatives of wheat demonstrate a great potential to enhance resistance of wheat to FHB.