Agronomic Options Research Articles

Key norisoprenoid compounds in wines from early-harvested grapes in view of climate change

In view of climate change, the scheduling of an early harvest may be an agronomic option to limit wine alcohol, provided that a satisfactory content of secondary metabolites can be ensured in grapes. To better understand the link between grape ripening, seasonal trend and wine aroma, the aromatic expression of Barbera and Pinot Noir wines produced with early harvested grapes was assessed. Attention was focused on C13 norisoprenoids during both alcoholic fermentation and after three months of storage. At the end of fermentation, the highest β-damascenone content was detected in wines obtained from less ripe grapes, the content subsequently increased significantly after three months of storage; however, the levels of β-ionone decreased significantly during the same period. The reduction of wine alcohol as a result of harvesting earlier, especially for Barbera, was associated with optimal aromatic levels as well as good technological parameters.

Crop production with limited irrigation: A review

When water supplies are restricted, so that full evapotranspiration demands cannot be met, limited irrigation is practised. Management strategy of limited irrigation is to optimise production per unit of applied water rather than to maximise yield per unit of land. Principles that help to facilitate limited irrigation strategies can be broadly grouped into three: agricultural water management, crop considerations and agronomic options. When anticipating low water year, choose crops which maximise production with limited water. In decreasing order of efficiency, short season indeterminate and long season indeterminate crops should be chosen judiciously. Deficit irrigation practices, localised irrigation methods, reducing water losses,conjunctive use of water resources etc can help minimise yield losses due to soil moisture stress. Additional agronomic management options that can maximise production include conservation tillage, advancing or delaying planting dates in order to coincide the crop’s critical period with water availability, decreasing plant competition byreducing seeding density and controlling weeds. Available options to address the challenge of limited irrigation have been briefly presented.

Integrated management strategy for improving the grain yield and nitrogen-use efficiency of winter wheat

Understanding of how combinations of agronomic options can be used to improve the grain yield and nitrogen use efficiency (NUE) of winter wheat is limited. A three-year experiment involving four integrated management strategies was conducted from 2013 to 2015 in Tai'an, Shandong Province, China, to evaluate changes in grain yield and NUE. The integrated management treatments were as follows: current practice (T1); improvement of current practice (T2); high-yield management (T3), which aimed to maximize grain yield regardless of the cost of resource inputs; and integrated soil and crop system management (T4) with a higher seeding rate, delayed sowing date, and optimized nutrient management. Seeding rates increased by 75 seeds m−2 with each treatment from T1 (225 seeds m−2) to T4 (450 seeds m−2). The sowing dates were delayed from T1 (5th Oct.) to T2 and T3 (8th Oct.), and to T4 treatment (12th Oct.). T1, T2, T3, and T4 received 315, 210, 315, and 240 kg N ha−1, 120, 90, 210 and 120 kg P2O5 ha−1, 30, 75, 90, and 45 kg K2O ha−1, respectively. The ratio of basal application to topdressing for T1, T2, T3, and T4 was 6:4, 5:5, 4:6, and 4:6, respectively, with the N topdressing applied at regreening for T1 and at jointing stage for T2, T3, and T4. The P fertilizers in all treatments were applied as basal fertilizer. The K fertilizer for T1 and T2 was applied as basal fertilizer while the ratio of basal application to topdressing (at jointing stage) of K fertilizer for both T3 and T4 was 6:4. T1, T2, T3, and T4 were irrigated five, four, four and three times, respectively. Treatment T3 produced the highest grain yield among all treatments over three years and the average yield was 9 277.96 kg ha−1. Grain yield averaged across three years with the T4 treatment (8 892.93 kg ha−1) was 95.85% of that with T3 and was 21.72 and 6.10% higher than that with T1 (7 305.95 kg ha−1) and T2 (8 381.41 kg ha−1), respectively. Treatment T2 produced the highest NUE of all the integrated treatments. The NUE with T4 was 95.36% of that with T2 and was 51.91 and 25.62% higher than that with T1 and T3, respectively. The N uptake efficiency (UPE) averaged across three years with T4 was 50.75 and 16.62% higher than that with T1 and T3, respectively. The N utilization efficiency (UTE) averaged across three years with T4 was 7.74% higher than that with T3. The increased UPE with T4 compared with T3 could be attributed mostly to the lower available N in T4, while the increased UTE with T4 was mainly due to the highest N harvest index and low grain N concentration, which consequently led to improved NUE. The net profit for T4 was the highest among four treatments and was 174.94, 22.27, and 28.10% higher than that for T1, T2, and T3, respectively. Therefore, the T4 treatment should be a recommendable management strategy to obtain high grain yield, high NUE, and high economic benefits in the target region, although further improvements of NUE are required.

System of crop intensification for more productive, resource-conserving, climate-resilient, and sustainable agriculture: experience with diverse crops in varying agroecologies

ABSTRACTWith continually increasing demand for food accompanied by the constraints of climate change and the availability and quality of soil and water, the world’s farmers are challenged to produce more food per hectare with less water, and with fewer agrochemical inputs if possible. The ideas and methods of the system of rice intensification which is improving irrigated rice production are now being extended/adapted to many other crops: wheat, maize, finger millet, sugarcane, tef, mustard, legumes, vegetables, and even spices. Promoting better root growth and enhancing the soil’s fertility with organic materials are being found effective means for raising the yields of many crop plants with less water, less fertilizer, reduced seeds, fewer agrochemicals, and greater climate resilience. In this article, we review what is becoming known about various farmer-centred innovations for agroecological crop management that can contribute to agricultural sustainability. These changes represent the emerging system of crop intensification, which is being increasingly applied in Asian, African, and Latin American countries. More research will be needed to verify the efficacy and impact of these innovations and to clarify their conditions and limits. But as no negative effects for human or environmental health have been identified, making these agronomic options more widely known should prompt more investigation and, to the extent justified by results, utilization of these methodologies.

The Impacts of Nano-Structured Nutrients on Chickpea Performance under Supplemental Irrigation

Chickpea is a legume of the family Fabaceae and the most widely grown crop in the semi‑arid Mediterranean regions. This pulse crop can grow on almost any soil and is well adapted to the semi‑arid conditions, but for good growth it requires a fertile soil with good residual moisture. Therefore, nutrient‑and water‑management practices are necessary agronomic options to improve chickpea production. The objective of this study was to evaluate the effect of different conventional and nano‑fertilizers on growth and yield of Kabuli chickpea under supplemental irrigation. The experiment was carried out at a research field in dry highland of Maragheh, North western Iran. Plants were grown under rainfed situation during the vegetative growth and supplement irrigations was applied during flowering and seed filling stages. The effect of nine nutrient treatments including T1: control (no fertilizer application), T2: nano‑chelated iron, T3: nano‑chelated manganese, T4: nano‑chelated copper, T5: nano‑chelated boron, T6: organic manganese, T7: conventional NPK fertilizer, T8: multi‑nutrient nano‑fertilizer and T9: nano‑chelated zinc were evaluated. Result showed that application of multi‑nutrient nano‑fertilizer, conventional NPK fertilizer and nano‑chelated Zn considerably improved the both vegetative growth (e.g. plant height, canopy width, number of the branches) and yield components. Also the highest chlorophyll concentration (P < 0.05) was recorded for plant grown by application of multi‑nutrient / compound fertilizers. There was a significant positive correlation between chlorophyll concentration and seed yield components (P < 0.01). Among the applied micronutrients, plants significantly responded to nano‑chelated Zn. Conventional NPK significantly improved the lateral growth (canopy width, ground cover, branches numbers).The results pointed out that the best performance of chickpea could be achievable through utilization of nano‑ of multi‑nutrient fertilizer, with the simultaneous release of micronutrients and macronutrients. The findings provided illustrative information in order to appreciate the importance of balanced crop nutrition in semi‑arid Mediterranean region.

Maize and Potato Intercropping: A Technology to Increase Productivity and Profitability in Tigray

Abstract Smallholders have limited landholding in the highlands of Tigray and therefore there is a critical need to improve land use efficiency (LUE). One way to improve the LUE is through intercropping of companion crops including maize and potato. An experiment was conducted to evaluate the intercropping ratio as a means to improve land use efficiency during the 2012 cropping season. The treatments tested were three intercropping ratios of maize: potato in 1:1, 1:2, 2:1 row arrangement compared against the maize and potato only cropping. The objective of the study was to identify the best intercropping ratio that maximizes land use efficiency. Land equivalent ratio (LER) was used to compare the land use efficiency of the intercrops with each sole crop. The total yield of intercropped crops were greater than sole cropping, shown by LER>1. The overall advantage of intercropping ranged from 35 to 58%. The highest land equivalent value of 58% was recorded for one maize and two potato rows arrangements indicated a yield advantage of 58% over sole crop. The partial land equivalent value of both crops in intercropping was less than one indicating the cohesiveness of both crops in intercropping. Thus, it can be concluded that 1maize: 2 potato intercropping is a viable agronomic option in increasing land use efficiency and increased food security. It is, therefore, imperative to demonstrate the best treatment under farmer’s condition.

Physiological responses of genotypes soybean to simulated drought stress

Received: 2016-11-23 | Accepted: 2016-04-14 | Available online: 2016-12-22 http://dx.doi.org/10.15414/afz.2016.19.04.157-162 The objective of this research was to investigate possible genetic variation in the sensitivity of soybean cultivars for nitrogen fixation rates in response to soil drying. The work confirmed that the selected physiological characteristics (RWC, osmotic potential, stress index and created nodules on roots) are good evaluating parameters for the determination of water stress in plant. In the floricultural year 2014 an experiment with four genetic resources of soybean was launched. Sowing of Maverick (USA), Drina (HRV), Nigra (SVK) and Polanka (CZK) genotypes was carried out in the containers of 15 l capacity. This stress had a negative impact on the physiological parameters. By comparing the RWC values, the decrease was more significant at the end of dehydration, which was monitored in Maverick and Drina genotypes using the Nitrazon inoculants and water stress effect. Inoculated stressed Nigra and Polanka genotypes have kept higher water content till the end of dehydration period. Also the proline accumulation was monitored during the water stress, whilst higher content of free proline reached of Maverick. More remarkable decrease of osmotic potential was again registered in a foreign Drina and Maverick genotypes in the inoculated variations. Nigra and Polanka genotypes responses not so significant in the given conditions. Key words: soybean, drought, stress, inoculation of Nitrazon References CANDRAKOVA, E. and LISKA, E. (2006) Vplyv teplotných a vlahových podmienok na tvorbu urody hrachu siateho, Influence of Temperature and Water Conditions on Field Pea Yield Formation. Acta fytotechnica et zootechnica, vol. 9, no. 3, pp. 57-61. DOWNIE, J. A. (1998) Functions of rhizobial nodulation genes. In Spaink, H. P., Kondorosi A. and Hooykaas, P. J. J. (ed.), Rhizobiacee. Dordrecht: Kluwer Academic Publisher, pp. 387. FAROOQ, M. et. al. (2009) Plant drought stress: effects, mechanisms and management. Journal of Sustainable Agriculture, pp. 153–188. doi: http://dx.doi.org/10.1080/10440040802548555 FISCHER, R.A. and MAURER, R. (1978) Drought resistance in spring wheat cultivars. I. Grain yield response. Aust. J. Agric. Res., vol. 29, pp. 897–907. doi: http://dx.doi.org/10.1071/AR9780897 FREDERICK, J.R., CAMP, C.R. and BAUER, P.J. (2001) Drought-stress effects on branch and mainstem seed yield and yield components of determinate soybean. Crop Science, vol. 41, no. 3, pp. 759-763. doi: http://dx.doi.org/10.2135/cropsci2001 JAMES, A. T., LAWN R. J. and COOPER, M. (2008) Genotypic variation for drought stress response traits in soybean. I. Variation in soybean and wild Glycine spp. for epidermal conductance, osmotic potential, and relative water content. Australian Journal of Agricultural Research, vol. 59, no.7, pp. 656–669. doi: http://dx.doi.org/10.1071/AR07159 KU, Y. S., AU-YEUNG, W. K. and YUNG, Y. L. (2013) Drought Stress and Tolerance in Soybean. Chapter 10. http://dx.doi.org/ 10.5772/52945 LEPORT, L. et aL. (2003) Physiological responses of cool-season grain legumes to drought in the lowrainfall Mediterranean environment of south-western Australia. In: N.P. Saxena (Ed.), Management of Agricultural Drought: Agronomic and Genetic Options, pp. 163–172, Enfield: Science Publishers. MALHOTRA, R.S., SARKER, A. and SAXENA, M.C. (2004) Drought tolerance in chickpea and lentil-present status and future strategies. Challenges and Strategies for Dryland Agriculture, no. 32, pp. 257–273. MIRABELLLA, R., (2004) Role of ROP GTPases and NodFactor Signaling in Medicago Root Nodule Infection: Thesis. Wageningen: Wageningen University, 160p. PATTERSON, T.G. and LARNE, T.A. (1983) Nitrogen fixation by soybeans. Seasonal and cultivar effects, and comparison of estimates. Crop Science, vol. 23, no.3, pp. 488-492. doi: http://dx.doi.org/10.2135/cropsci1983.0011183X002300030012x RASAEI, B., GHOBADI, M.E. and AMIRI, M. K. (2013) Effect of osmotic potential on germination and seedling characteristics of soybean seeds. International Journal of Agriculture and Crop Sciences. vol., 5, no.11, 1265-1268. RICCARDI, L.,POLIGNANO, G.B. and DE GIOVANNI, C. (2001) Genotypic response of Faba bean to water stress. Euphytica, vol.118, no.1. pp. 39–46. doi: http://dx.doi.org/10.1023/A:1004078017159 SANCHOLI, G., MOBASSER, H. R. and FANAEI, H. R. (2015) Effect Inoculation of Soybean Cultivars with bacteria Rhizobium japonicum in Sistan. Biological Forum – An International Journal no.1, pp. 552-558. ISSN 0975-1130. SADEGHIPOUR, O. and ABBASI, S. (2012) Soybean response to drought and seed inoculation. World Applied Sciences Journal, vol.1, no.1, pp. 55-60. doi: http://dx.doi.org/10.1111/j.1467-6486.2004.00462.x VIRGINIA, S., PAGAN, M. and COOPER, M. (2012) Genetic Analysis of Relative Water Content (RWC) in Two Recombinant Inbred Line Populations of Soybean [Glycine max (L.) Merr.] Journal of Plant Genome Sciences, vol. 1, no. 2. doi: http://dx.doi.org/10.5147/jpgs.2012.0058

Applying Limestone or Basalt in Combination with Bio-Fertilizer to Sustain Rice Production on an Acid Sulfate Soil in Malaysia

A study was conducted to determine the efficacy of applying ground magnesium limestone (GML) or ground basalt in combination with bio-fertilizer to sustain rice production on an acid sulfate soil in Malaysia. Soils from Kelantan Plains, Malaysia, were treated with GML, ground basalt, bio-fertilizer, GML + bio-fertilizer, and ground basalt + bio-fertilizer (4 t·ha−1 each). Results showed that soil fertility was improved by applying the soil amendments. GML and basalt contain some Zn and Cu; thus, application of these amendments would increase their contents in the soil needed for the healthy growth of rice. Basalt applied in combination with bio-fertilizer appeared to be the best agronomic option to improve the fertility of acid sulfate soils for sustainable rice production in the long run. In addition to increasing Ca, Mg, Zn, and Cu reserves in the soil, water pH increased and precipitated Al3+ and/or Fe2+. Ground basalt is cheaper than GML, but basalt dissolution in the acidic soil was slow. As such, its ameliorative effects could only be seen significantly from the second season onwards. The specially-formulated bio-fertilizer for alleviating the infertility of acid sulfate soil could also enhance rice growth. The use of the bio-fertilizer fortified with N2-fixing bacteria is a green technology that would help reduce NO3− and/or NO2− pollution and reduce the cost of rice production. The phosphate-solubilizing bacteria (PSB) present in the bio-fertilizer not only increased the available P, but also helped release organic acids that would inactivate Al3+ and/or Fe2+ via the process of chelation.

Effect of nano-silicon foliar application on safflower growth under organic and inorganic fertilizer regimes

Abstract Silicon nanoparticles have distinctive physicochemical characteristics and are able to enter into plants and impact the metabolism of plants as well as improve plant growth and yield under unfavourable environmental conditions. Besides, low soil organic matter content, imbalanced nutrient and inadequate water supply may adversely affect crop productivity in semiarid areas. To understand the effects of foliar spray of silicon dioxide nanoparticles (nSiO2) with application of farmyard manure (FYM) or inorganic fertilizer on morpho-physiological traits and yield of safflower, a field experiment was carried out in a highland semiarid region of Maragheh, northwest Iran. The experiment consisted of two levels of nSiO2 (0 and 20 mM) and four fertilizer regimes (control, 15 t ha−1 FYM, 30 t ha−1 FYM, 90 kg ha−1 N-P-K chemical fertilizer). Safflower plants were treated with nSiO2 suspension at leaf development, branching and capitulum emergence stages. Although the nSiO2 significantly improved some growth parameters such as canopy spread, stem diameter, plant height, ground cover and the number of achenes in capitulum, it did not affect achene yield and harvest index. However, fertilizer treatments considerably affected most of morpho-physiological traits, achene yield and yield components. The result showed that the best growth and the highest achene yield were achieved by application of 30 t ha−1 FYM before sowing. Application of high FYM increased the achene yield by 48% compared to the control, however, application of N-P-K chemical fertilizer or of 15 t ha−1 FYM improved achene yield only up to 17% over the no fertilizer condition. Moreover, this work revealed some positive effects of exogenous application of nSiO2 on safflower growth. This finding suggests that application of organic fertilizers with foliar spray of nSiO2 can improve safflower production and is an advisable agronomic option.

THE IMPACT OF SEED PRIMING AND ROW SPACING ON THE PRODUCTIVITY OF DIFFERENT CULTIVARS OF IRRIGATED WHEAT UNDER EARLY SEASON DROUGHT

SUMMARYThis study was conducted to improve wheat production under vegetative (early season) drought stress. Hydroprimed and osmoprimed (with CaCl2) seeds of wheat cultivars Lasani-2008 (LS-2008) and Triple Dwarf-1 (TD-1), were sown in 20 (narrow), 25 (medium), and 30 cm (wider) spaced rows. Crop was grown under well-watered conditions till physiological maturity or was subjected to drought stress (50% field capacity) during vegetative phase and then grown under well-watered conditions. Drought stress caused substantial reduction in grain and biological yields, related traits, harvest index (HI) and water use efficiency (WUE). Nonetheless, planting osmoprimed seeds in narrowly spaced rows significantly improved the grain yield, HI and WUE. However, wheat planted in wider rows had bold grains. Furthermore, wheat cultivar LS-2008 produced better yield, even under drought stress, than cultivar TD-1. Economic analysis indicated that planting osmoprimed seeds of wheat cultivar LS-2008 in narrowly spaced rows under early season drought yielded maximum economic benefits. In conclusion, planting osmoprimed seeds of cultivar LS-2008 in narrowly spaced rows is a good agronomic option to improve the wheat performance under early season drought stress.

Towards sustainable use of water in rainfed and irrigated cropping systems: review of some technical and policy issues

Water sustainability in agriculture is the main topic of this review. However, moving from studies carried out at worldwide level, the main focus of the paper is the Mediterranean farm which practices irrigated and/or rainfed cropping systems. On the basis of the state of the art on this matter, a lack of knowledge in some areas has come to light that calls for new policies and further research. Basically, the review provides feasible agro-technical solutions for using water in the most efficient and productive way. Alternative ways to use water resources rationally in growing crops are discussed. They are based mainly on progress due to agronomy (No-Till Conservation Agriculture), information technology (Decision Support System and Precision Irrigation) and genetics. Agronomic options are analysed taking into account recent European agricultural and environmental trends of policies which conjugate the issues related to sustainability and production intensification. In perspective, the review encourages discussion on how to relocate farming systems within natural cycles, specifically those of the water cycle, based on No-Till Conservation Agriculture principles and practices which apply to all land-based agro-ecologies in all continents where agriculture is practiced.

Analysis of chickpea yield gap and water-limited potential yield in Iran

Iran is one of the major chickpea (Cicer arietinum L.) producing countries of the world. Average chickpea yield in Iran is about 500kg ha−1 while the world average is 900kgha−1. The objective of this study was to investigate chickpea water limited potential yield (Yw) and yield gap in Iran. The analysis was based on data from five representing chickpea producing locations of Iran. Estimated country Yw and yield gap were 991 and 463kgha−1, respectively, indicating that farmers have reached 53% (range: 38–64%) of Yw. If farmers could reach 80% of Yw of their locations, by improving agronomy practice, country average yield would increase by 50%, from 528 to 793kgha−1. A key finding of the study was that chickpea yield in Iran is largely limited by inefficient use of environmental resources and not the genetics of the current cultivars. Much higher yield increase is obtainable via an agronomic option than a genetic improvement option: using shorter duration cultivars increased Yw to 1237kgha−1 (25% increase), but applying a single irrigation of 60mm at first-pod alone or in combination with shorter duration cultivars increased Yw to 1804kgha−1(85% increase) and to 1997kgha−1 (104% increase), respectively. Thus, tripling chickpea production would be feasible using a single irrigation with or without shorter duration cultivars (from 528 to 1443 or 1598kgha−1). The availability of water for the single irrigation is discussed.

English

In Malawi, increasing human population and low productivity of cassava (Manihot esculenta [Crantz]), the second most important food crop after maize, necessitate the intensification of agronomic options for cassava production. A study was therefore conducted in 2012-2013 season on a chromic Luvisol at Bunda College (14° 35 S’; 33° 50 E’), Central Malawi, to evaluate the effects of inorganic fertilizer (kg ha-1 N : P2O5 : K2O : S at 0 and 46:42:0:8) and cattle manure (0, 5 and 10 t ha-1) on cassava growth and yield in a 3 x 2 factorial randomized complete block design replicated four times. The sweet variety Mbundumali with 9-15 months maturity and potential yield of 25 t/ha was used. The study site’s inherent soil chemical characteristics in the 15-30 cm depth were: P = 102 ppm, K = 3.87 meq 100g-1, N = 0.16%, pH = 5.4, organic matter = 1.79 and N = 0.064. From the results, tuber fresh yield was significantly increased by application of both cattle manure (P = 0.043) and inorganic fertilizer (P = 0.001) while there was no significant manure x inorganic fertilizer interaction. Tuber fresh yield was maximum at 27.6 t/ha with application of cattle manure at 5 t ha-1, however increasing the rate of cattle manure to 10 tha-1 did not increase the tuber yield further. Fresh tuber yield increased from 22.8 to 29.2 t ha-1 with inorganic fertilizer application. Yield without fertility amendments was 21 t ha-1, suggesting that appropriate amendments may raise yields above potential. There were also significant effects of inorganic fertilizer on branches per plant, tubers per plant and tuber length, while manure had no effect on these variables.   Key words: Cassava, cattle dung, integrated soil fertility management, cassava growth.

Zero Tilled Dibbled Sunflower Enables Planting Earlier and Harvests More in the Coastal Saline Area of Bangladesh

 Abstract—Only transplanted Aman (T. Aman) rice is one of the major cropping sequences in the medium saline, irrigation water lacking area of the coastal Bangladesh which requires suitable succeeding crop with early planting in moist soil and to escape damage from the effect of storm surges and water logging due to rainfall in May. A field trial was conducted in 2012 to compare the early dibbled sunflowers in zero tilled soil with traditional tilled one after T. Aman rice. Sunflower was planted on four dates, 14 January (zero tillage in moist soil), 22 and 29 February and 5 March (tilled field at field capacity). Results indicated that dibbling on 14 January produced significantly taller plant, larger head and higher seed yield (3.06 t ha -1 ) than those of other planting dates (2.54 to 2.68 t ha -1 ). The mid-December and from about 23% area in late December (3). Most of the coastal areas are dominated by medium highlands, where flooding depth ranges from 0.3-0.9 meter. This category of land is suitable for minimum two crops and sometimes three crops. But only medium to long duration transplanted Aman (T. Aman) rice (wet season rice) is the predominant cropping sequence in the region. The slow drying process after harvest of T. Aman rice delayed to reach the soil in field condition or suitable for ploughing the land for dry season winter (rabi) and pre-mosoon crops. Generally the situation leads to seeding of rabi crops during the first fortnight of February which is often affected by soil salinity. The cultivation of dry season crop in this worse situation requires suitable crops and agronomic options suitable for early planting in the excess moist soil, more than field capacity which is unable to plough to increase the productivity and cropping intensity. The cultivation of sunflower may be suitable in this environment because of its high yield as well as its extensive adaptability and acclimation, high photosynthesis potential and high harvest

Integrated nutrient, water and other agronomic options to enhance rice grain yield and N use efficiency in double-season rice crop

Options to increase resource use efficiency and climatic yield potential of locally adapted super rice hybrids including combined water, nutrient and other agronomic management are limited. Hence, the aim of our three-year (six seasons) experiments during early-season (ESR; Luliangyou996) and late-season (LSR; C-liangyou396) rice in southern China was to identify key yield parameters and optimum resource use options to enhance the crop's climatic yield potential. Grain yield averaged across all three years with effective N management combined with post-anthesis shallow wetting and drying was 32.8% and 37.1% higher than the normal farmers’ practice in Liuyang County in ESR and LSR, respectively. More spikeletsm−2 were the key to achieving high yield potential, further supported by increased leaf area index and high radiation interception and internal use efficiency. The split application of nitrogen in combination with shallow wetting and drying allowed for better N uptake, use efficiency and partitioning, leading to enhanced biomass and yield. The high yield potential, however, was not just a function of genetics and management but also depended on the climatic conditions prevailing, particularly temperature and radiation. In ESR, lower temperature during vegetative stage reduced overall biomass and sink size while subsequent higher temperature reduced the total grain filling period by 17 days compared with LSR, indicating a climatic condition-driven decline in yield potential rather than lower genetic potential of the super hybrids. A lack of correlation of spikeletspanicle−1 and spikeletsm−2 with grain-filling percentage in LSR provided evidence that a larger sink does not necessarily result in poor grain filling when sufficient time and assimilates for grain filling are provided, which is more climate dependent. Our work highlights the benefits of integrating nutrient, water and agronomic management options to achieve high NUE and grain yield.

Soybean yield in response to application of phosphate rock associated with triple superphosphate

Soybean (Glycine max L. Merrill) crop started to be planted in the Brazilian Cerrado in the 1970's, and this region currently contributes with 57% of total soybean production in Brazil. Under natural conditions in this region, the soils present chemical limitations such as low pH, low Cation Exchange Capacity, low nutrient availability, and moreover, clayey soils have a high P fixation capacity mainly due to high contents of Fe/Al oxides. Since P is the most limiting nutrient is this region, a study was performed in the state of Maranhão, Brazil, in a Typic Hapludox, with clayey texture and low available P (extracted by resin). Treatments were defined to evaluate soybean response to broadcast Arad phosphate rock (PR) plus banded triple superphosphate (TSP) and to evaluate the soybean response to three proportions of PR and TSP. The experiment was established in October 2004 and was carried out for three consecutive crop years (2004/05 to 2006/07). The associated use of PR and TSP, in several situations, resulted in yields at least similar to that obtained with the use of the water soluble P source and, in some cases, even using lower P rates. Regarding the "mixtures", a linear response was observed when they were banded; however, when they were broadcasted, no increase in yield was observed above 50% of relative solubility. In conclusion, the association of sources differing in solubility may be a feasible agronomic option for P fertilizer management of soybeans.

Agroecosystem management and biotic interactions: a review

Increasing the use of synthetic fertilisers and pesticides in agroecosystems has led to higher crop yields, accompanied by a decline in biodiversity at the levels of field, cropping system and farm. Biodiversity decline has been favoured by changes at landscape level such as regional farm specialisation, increases in field size, and the removal of hedgerows and woodlots. The loss of biodiversity in agroecosystems has increased the need for external inputs because beneficial functions are no longer provided by beneficial species as natural enemies of crop pests and ecosystem engineers. This trend has led to a strong reliance on petrochemicals in agroecosystems. However, many scientists have been arguing for more than two decades that this reliance on petrochemicals could be considerably reduced by a better use of biotic interactions. This article reviews options to increase beneficial biotic interactions in agroecosystems and to improve pest management and crop nutrition whilst decreasing petrochemical use. Four agronomic options are presented. First, it has been shown that the choice of cultivar, the sowing date and nitrogen fertilisation practices can be manipulated to prevent interactions between pests and crop, in either time or space. Nevertheless, the efficacy of these manipulations may be limited by pest adaptation. Second, beneficial biotic interactions may result from appropriate changes to the habitats of natural enemies and ecosystem engineers, mediated by soil and weed management. Here, knowledge is scarce, and indirect and complex effects are poorly understood. Third, changes achieved by crop diversification and, fourth, by landscape adaptation are promising. However, these practices also present drawbacks that may not necessarily be outweighed by beneficial effects. Overall, these four management approaches provide a powerful framework to develop sustainable agronomic practices.

Wheat physiology: a review of recent developments

This review focuses on recent advances in some key areas of wheat physiology, namely phasic development, determination of potential yield and water-limited potential yield, tolerance to some other abiotic stresses (aluminium, salt, heat shock), and simulation modelling. Applications of the new knowledge to breeding and crop agronomy are emphasized. The linking of relatively simple traits like time to flowering, and aluminium and salt tolerance, in each case to a small number of genes, is being greatly facilitated by the development of molecular gene markers, and there is some progress on the functional basis of these links, and likely application in breeding. However with more complex crop features like potential yield, progress at the gene level is negligible, and even that at the level of the physiology of seemingly important component traits (e.g., grain number, grain weight, soil water extraction, sensitivity to water shortage at meiosis) is patchy and generally slow although a few more heritable traits (e.g. carbon isotope discrimination, coleoptile length) are seeing application. This is despite the advent of smart tools for molecular analysis and for phenotyping, and the move to study genetic variation in soundly-constituted populations. Exploring the functional genomics of traits has a poor record of application; while trait validation in breeding appears underinvested. Simulation modeling is helping to unravel G × E interaction for yield, and is beginning to explore genetic variation in traits in this context, but adequate validation is often lacking. Simulation modelling to project agronomic options over time is, however, more successful, and has become an essential tool, probably because less uncertainty surrounds the influence of variable water and climate on the performance of a given cultivar. It is the ever-increasing complexity we are seeing with genetic variation which remains the greatest challenge for modelling, molecular biology, and indeed physiology, as they all seek to progress yield at a rate greater than empirical breeding is achieving.

Relationship of Soybean Aphid (Hemiptera: Aphididae) to Soybean Plant Nutrients, Landscape Structure, and Natural Enemies

In the north central United States, populations of the exotic soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), are highly variable across space, complicating effective aphid management. In this study we examined relationships of plant nutrients, landscape structure, and natural enemies with soybean aphid abundance across Iowa, Michigan, Minnesota, and Wisconsin, representing the range of conditions where soybean aphid outbreaks have occurred since its introduction. We sampled soybean aphid and its natural enemies, quantified vegetation land cover and measured soybean nutrients (potassium [K] and nitrogen [N]) in 26 soybean sites in 2005 and 2006. Multiple regression models found that aphid abundance was negatively associated with leaf K content in 2005, whereas it was negatively associated with habitat diversity (Simpson's index) and positively associated with leaf N content in 2006. These variables accounted for 25 and 27% of aphid variability in 2005 and 2006, respectively, suggesting that other sources of variability are also important. In addition, K content of soybean plants decreased with increasing prevalence of corn-soybean cropland in 2005, suggesting that landscapes that have a high intensification of agriculture (as indexed by increasing corn and soybean) are more likely to have higher aphid numbers. Soybean aphid natural enemies, 26 species of predators and parasitoids, was positively related to aphid abundance; however, enemy-to-aphid abundance ratios were inversely related to aphid density, suggesting that soybean aphids are able to escape control by resident natural enemies. Overall, soybean aphid abundance was most associated with soybean leaf chemistry and landscape heterogeneity. Agronomic options that can ameliorate K deficiency and maintaining heterogeneity in the landscape may reduce aphid risk.

Potential agronomic options for energy‐efficient sugar beet‐based bioethanol production in northern Japan

AbstractSugar beet (Beta vulgaris L. subsp. vulgaris) is deemed to be one of the most promising bioethanol feedstock crops in northern Japan. To establish viable sugar beet‐based bioethanol production systems, energy‐efficient protocols in sugar beet cultivation are being intensively sought. On this basis, the effects of alternative agronomic practices for sugar beet production on total energy inputs (from fuels and agricultural materials during cultivation and transportation) and ethanol yields (estimated from sugar yields) were assessed in terms of (i) direct drilling, (ii) reduced tillage (no moldboard plowing), (iii) no‐fungicide application, (iv) using a high‐yielding beet genotype, (v) delayed harvesting and (vi) root+crown harvesting. Compared with the conventional sugar beet production system used in the Tokachi region of Hokkaido, northern Japan, which makes use of transplants, direct drilling and no‐fungicide application contributed to reduced energy inputs from raising seedlings and fungicides, respectively, but sugar (or ethanol) yields were also reduced by these practices, to a greater equivalent extent than the reductions in energy inputs. Consequently, direct drilling (6.84 MJ L−1) and no‐fungicide application (7.78 MJ L−1) worsened the energy efficiency (total energy inputs to produce 1 L of ethanol), compared with conventional sugar beet production practices (5.82 MJ L−1). Sugar yields under conventional plow‐based tillage and reduced tillage practices were similar, but total energy inputs were reduced as a result of reduced fuel consumption from not plowing. Hence, reduced tillage showed improved energy efficiency (5.36 MJ L−1). The energy efficiency was also improved by using a high‐yielding genotype (5.23 MJ L−1) and root+crown harvesting (5.21 MJ L−1). For these practices, no major changes in total energy inputs were noted, but sugar yields were consistently increased. Neither total energy inputs nor ethanol yields were affected by extending the vegetative growing period by delaying harvesting.