Specific Growth Stages Research Articles

The value of decimal cereal growth stages

An online search for ‘cereal growth stages’ in Web of Science (http://wok.mimas.ac.uk/) shows that ‘The decimal code for the growth stages of cereals, with illustrations’ (Tottman, 1987) has been cited over 440 times. The aim of the paper was to bring precision to the description and interpretation of cereal growth stages. It was not the first paper published on decimal growth stages nor even the most highly cited and is a follow up to an earlier publication ‘An explanation of the decimal code for the growth stages of cereals, with illustrations’ (Tottman & Makepeace, 1979), which has been cited 280 times. The most highly cited (over 3900 citations) paper using the search term ‘cereal growth stages’ is an earlier paper proposing the decimalisation of cereal growth stages (Zadoks et al., 1974) which was a development of the Feekes scale (Feekes, 1941), as described and illustrated by Large (1954). While the Feekes scale was widely used and Large's 1954 paper has been cited over 1000 times, it was felt that there was a need to better describe the earlier stages of cereal growth in order to cover all small grain species growing in diverse environments (Tottman & Makepeace, 1979). The Feekes scale was also considered to be not so suitable for computerisation of data records (Zadoks et al., 1974). As Tottman's 1987 paper was not the first, why should it be considered influential? The answer is in its title and that of the preceding 1979 paper. Tottman & Makepeace (1979) took the scale proposed by Zadoks et al. (1974) and made it applicable beyond the academic world. The fuller descriptions of specific growth stages and the addition of illustrations in the 1979 and 1987 papers meant that non-specialists could identify the specific growth stages in key crops such as wheat and barley. Hilary Broad's excellent illustrations occupy 11 pages of the 1979 paper and 9 pages of the 1987 paper and the then Editors of the Annals of Applied Biology should be congratulated for their foresight in publishing so many pages of illustrations. The critical improvement in the 1987 paper was a fuller description of the assessment of growth stages, especially the critical stages around the onset of stem elongation [Decimal Growth Stages (DGS) 30–32]. These were accompanied by Hilary Broad's illustrations of sections through developing stems that enabled advisors and growers to determine when the majority of a crop had reached DGS 31–33, which has been adopted in the UK as the ‘T1’ stage, one of the key timing points for applying inputs such as fertilisers, fungicides and herbicides. The illustrations of key stages from the 1987 paper were reproduced on a double-sided guide published by the British Crop Protection Council in 1987 to ensure that they were available to crop scientists and growers throughout the UK. The Home Grown Cereals Authority (HGCA) subsequently made another double-sided guide available as paper and electronic copies in which they credit Tottman & Makepeace's (1979) paper but use the illustrations from Tottman's (1987) paper to describe the stages around stem elongation. I therefore argue that it is the 1987 paper that influenced the HGCA guide ‘Cereal growth stages – a guide for crop treatments’ (http://archive.hgca.com/document.aspx?fn=load&media_id=6831&publicationId=7240), which links the key application timings of T1, T2 and T3 to the appropriate DGS. HGCA also reproduces the key growth stages in ‘The wheat growth guide’ (http://archive.hgca.com/document.aspx?fn=load&media_id=4321&publicationId=4444) and ‘The barley growth guide’ (http://archive.hgca.com/publications/documents/cropresearch/barley_growth_guide.pdf). All these guides have been made widely available to advisors and growers and demonstrate how the decimal growth stages are used as a reference to a crop's behaviour throughout its life cycle. Such uses are not reflected in academic publication statistics but demonstrate that ‘The decimal code for the growth stages of cereals, with illustrations’ (Tottman, 1987) has been highly influential in cereal agriculture over at least 25 years and will continue to be so. The impact of the paper upon practical agriculture is difficult to quantify but it has been a key factor in improving applications of inputs like fertiliser, fungicides and herbicides for optimum effect and minimal wastage. I thank the Scottish Government's Rural and Environment Science and Analytical Services Division (RESAS) for funding.

Predicting the impact of climate change on water requirement of wheat in the semi-arid Indo-Gangetic Plains of India

Crop water requirement (CWR) under the projected climate change could be mediated through changes in other weather parameters including the air temperature. The present study was directed to assess the on-farm water requirement in wheat crop in future, in semi-arid Indo-Gangetic Plains of India, through field and computer simulations. Field simulation using temperature gradient tunnels shows 18% higher crop evapotranspiration (ETc) and 17% increase in root water extraction at 3.6°C elevated temperature compared to 1.5°C increase over the ambient. A time series model (ARIMA) with long-term (1984–2010) weather data of the experimental site and a global climate model (IPCC-SRES HADCM3) were used to simulate the potential ET (ET0) of wheat for 2020–2021 and 2050–2051 years. The crop coefficient (Kc) values for these years were generated through Kc–CGDD (Cumulative growing-degree-days) relation by using LARS-WG model-derived daily minimum and maximum temperatures. The CWR and NIR (Net Irrigation Requirement) are likely to be less in projected years even though air temperatures increase. The CWR reduces in ARIMA outputs owing to a lower reference ET (ET0) due to decline in solar radiation. Under IPCC-SRES scenarios, the ETc–crop phenophase relation [CGDD–LGP (length of growing period) response] may offset the effect of rising temperature and a net decline in CWR is observed. It may be likely that the effect of temperature increase on CWR is manifested mostly through its relation with crop phenophase (thermal requirement to complete a specific growth stage) and not the temperature effect on ET0 per se. This is certainly a ray of hope in managing the depleting irrigation water resources in the semi-arid wheat-growing regions of the IGP.

Seasonal variability of the main components in essential oil of Mentha × piperita L.

Mentha × piperita is an important and commonly used flavoring plant worldwide. Its constituents, primarily menthol and menthone, change in the essential oil depending on internal and external factors, of which environmental conditions appear very important. The experiment was established in 2010 for three vegetation season, in order to observe the quantitative changes of the main components of peppermint. The determination of menthol, menthone, limonene, menthyl acetate, menthofuran and β-caryophyllene was registered. In the experimental season 2011 and 2012 a higher mean temperature than in 2010 and extreme rainfall in July 2011 and 2012 were recorded. Different environmental conditions affected the development of M. × piperita plants and the content and composition of the essential oil. Seasonal and maturity variations are interlinked with each other, because the specific ontogenic growth stage differed as the season progressed. Fluctuations in monthly and seasonal temperature and precipitation patterns affected the quality of peppermint essential oil.

Impact of Simulated Threecornered Alfalfa Hopper (Hemiptera: Membracidae) Induced Plant Loss on Yield of Maturity Group IV and V Soybeans

Mainstem girdling of soybean seedlings by threecornered alfalfa hoppers, Spissistilus festinus (Say), can result in several plant responses: (1) death of the plant, usually within 2 - 3 wks of injury,(2) mainstem breakage at the girdle soon after girdling through maturity, (3) partial breakage at the girdle with continued plant growth, (4) or the injured area (girdle) may heal over and the plant remain upright. Studies were conducted to simulate plant loss occurring during the reproductive growth stages which would result from threecornered alfalfa hopper injury during the early vegetative growth stages and examine the impact of this plant loss on yield of full-season indeterminate, late-planted/double-crop indeterminate, and full-season determinate soybeans, Glycine max (L.) Merr., at specific reproductive growth stages. Yield of full-season indeterminate soybeans was reduced by 6.4 - 15% when plant loss exceeded 20% at the R1–R2 growth stage. At R3 and R5, yields were reduced 7.4 - 30% and 7.2% to 32.1%, respectively, when plant density was reduced by ≥ 10%. For late-planted / double-crop indeterminate soybeans, yield losses of 10.6% to 19.3% occurred when plant loss exceeded 30% at the R1–R2 growth stage. Yields were reduced 6.9% to 20.6% at R3 when plant loss was ≥ 20. At the R5 growth stage, yields were reduced 22.4 - 40% when plant density was reduced by ≥ 30%.

Timing of Episodic Drought Can Be Critical in Cotton

Episodes of drought stress in upland cotton (Gossypium hirsutum L.) can be detrimental to vegetative growth, yield characteristics, and fiber quality, depending on the specific growth stage drought occurs. Growth, yield, fiber quality, and boll distribution were compared among four cotton cultivars subjected to four growth‐stage specific drought periods that were repeated in three studies over 2 yr in West Texas. Drought timings occurred at pinhead square, early bloom, and two periods of stress during peak bloom. Both years of the study were hot and dry, with minimal rainfall during the episodic drought treatments. Yield was not significantly different among cultivars, nor was there a significant cultivar × irrigation interaction related to cotton yield. However, there were differential effects on fiber quality among cultivars subjected to the different episodic drought timings. Drought stress during squaring resulted in significantly shorter plants with fewer nodes; however, yield was comparable to the highest yields among the other drought stress treatments, and fiber quality parameters were significantly improved compared to all other treatments except full irrigation. The early flowering growth stage was the most sensitive to drought stress and produced the lowest yields, the lowest fruit retention, and poor fiber quality. Drought events at peak bloom resulted in similar yield losses to those at squaring, but poorer fiber quality. This information may be crucial for producers who either have competing demands for water resources or who want to maximize profits or resources after the occurrence of a drought episode.

Determination of Water Requirement and Crop Coefficient for Sorghum (<i>Sorghum bicolor L</i>.) at Melkassa, Ethiopia

Knowledge of crop evapotranspiration (ETc), the combined process of evaporation and plant transpiration, is important in agriculture for scheduling farm operations and designing and managing irrigation and drainage systems. Development of crop coefficient (Kc) can enhance crop evapotranspiration (ETc) estimates in specific crop growth stages. However, locally determined Kc information is not available for many important crops in Ethiopia. This research was, therefore, conducted to determine growth stage specific Kc and crop water use for sorghum (Sorghum bicolor L.) var. Gambella-1107 at the Melkassa Agricultural Research Center which is located in a semi arid climate zone in Ethiopia. Drainage type lysimeter was used to measure Gambella-1107 crop water use under water balance system on a clay loam soil and local weather data were used to determine the reference evapotranspiration (ETo). Crop coefficient was developed from measured ETc and ETo calculated using weather data. The growth stages of the crop were assessed as the seasonal change of plant height (pH), leaf area (LA) and leaf area index (LAI). The yield obtained was 5.3 t ha-1 and the measured LAI were 0.2, 4.2, 4.9 and 1.6 at the initial, development, midseason and late season stages, respectively. The maximum LAI was achieved when the plants reach their maximum height at mid-season stage with high crop evapotranspiration due to leaf enlargement that increases transpiration. The measured ETc values were 53.8, 138.5, 214.4, and 94.0 mm during the initial, development, midseason and late-season stages, respectively, and the seasonal total value was 500.7 mm. The calculated Kc values for the crop were 0.45, 0.83, 1.18 and 0.78 during the initial, development, mid-season and late-season stages, respectively. These values were greater than those reported in FAO publication for sorghum varieties which could be a result of soil, climate and crop genetic differences. This suggests the need for developing site-specific Kc values for proper irrigation management.

Growth and expansion of strawberry fruit (Fragaria x ananassa Duch.) under water stress conditions

This investigation was carried out to find out if a constant number of strawberry fruit in the plants would have differing rates of growth and expansion when subjected to different levels of water stress at specific growth stages. Soil water stress treatments were imposed at flowering (flo) and at fruiting (fru), by withholding water until the available soil water were 0.40 to 0.45% v/v for the normal stress treatment (normal), 0.35 to 0.40% v/v mild stress (ms) and 0.25 to 0.35% v/v for severe stress (ss). The ms fru, ss fru and ss flo treatments showed significantly lower fruit weights than other treatments while fruit firmness was significantly increased by ms fru and ss fru treatments in the primary, secondary fruit and tertiary fruit. The total soluble solids (TSS) were not affected significantly by the water stress treatments. Osmotic adjustment may be attributed to the ability of the water stressed strawberry fruit to grow and expand post anthesis. This research provides an understanding of the effects of water deficits on fruit quality when other factors such as fruit number and fruit positioning on the inflorescence are similar in all experimental units. Strawberry producers may consider reduced crop loading to ameliorate reduced fruit size, when faced with water deficit irrigation regimes. Key words: Crop load, fruit size, fruit weight, total soluble solids (TSS), water stress.

Transcriptional Reprogramming of Wheat and the Hemibiotrophic Pathogen Septoria tritici during Two Phases of the Compatible Interaction

The disease septoria leaf blotch of wheat, caused by fungal pathogen Septoria tritici, is of worldwide concern. The fungus exhibits a hemibiotrophic lifestyle, with a long symptomless, biotrophic phase followed by a sudden transition to necrotrophy associated with host necrosis. Little is known about the systematic interaction between fungal pathogenicity and host responses at specific growth stages and the factors triggering the transition. In order to gain some insights into global transcriptome alterations in both host and pathogen during the two phases of the compatible interaction, disease transition was monitored using pathogenesis-related gene markers and H2O2 signature prior to RNA-Seq. Transcriptome analysis revealed that the slow symptomless growth was accompanied by minor metabolic responses and slightly suppressed defences in the host, whereas necrotrophic growth was associated with enhanced host responses involving energy metabolism, transport, signalling, defence and oxidative stress as well as a decrease in photosynthesis. The fungus expresses distinct classes of stage-specific genes encoding potential effectors, probably first suppressing plant defence responses/facilitating the symptomless growth and later triggering life style transition and inducing host necrosis/facilitating the necrotrophic growth. Transport, signalling, anti-oxidative stress mechanisms and apoplastic nutrient acquisition play important roles in the entire infection process of S. tritici. Our findings uncover systematic S. tritici-induced expression profiles of wheat related to specific fungal infection strategies and provide a transcriptome resource for studying both hosts and pathogens in plant-Dothideomycete interactions.

Intriguing properties of the angucycline antibiotic auricin and complex regulation of its biosynthesis

Streptomyces bacteria are major producers of bioactive natural products, including many antibiotics. We identified a gene cluster, aur1, in a large linear plasmid of Streptomyces aureofaciens CCM3239. The cluster is responsible for the production of a new angucycline polyketide antibiotic auricin. Several tailoring biosynthetic genes were scatted in rather distant aur1 flanking regions. Auricin was produced in a very narrow growth phase interval of several hours after entry into stationary phase, after which it was degraded to non-active metabolites because of its instability at the high pH values reached after the production stage. Strict transcriptional regulation of the auricin biosynthetic gene cluster has been demonstrated, including feed-forward and feedback control by auricin intermediates via several of the huge number of regulatory genes present in the aur1 cluster. The complex mechanism may ensure strict confinement of auricin production to a specific growth stage.

Effects of air temperature and air flow rate control on the tipburn occurrence of leaf lettuce in a closed-type plant factory system

This study aimed to establish a practical method to reduce tipburn symptoms on leaf lettuce cultivars in a closed plant factory system, focusing on air temperature conversion at specific plant growth stages and artificial air flow application strategies using pre-screened tipburn-sensitive cultivars. Inter-conversion effect of day temperature among 18, 22, and 25°C, 12 days after transplanting on tipburn occurrences, were compared with stable day temperature condition. Horizontal air flow rates were controlled at 0.28 (Low), 0.55 (Medium), and 1.04 m·s−1 (High). Tipburn occurrences were highly variable depending on the lettuce cultivars tested. Following the initial screening of 28 leaf lettuce cultivars under 3 different light intensity conditions (ranging from 150 to 250 mol·m−2·s−1), two cultivars exhibiting relatively higher percentages of tipburn were selected for the following air temperature and air flow treatments. None of the temperature treatments effectively reduced tipburn symptom, while adjusting the temperature to a lower day temperatures at 12 days after transplanting only had a minor effect on lettuce growth and tipburn occurrence. In contrast, stable horizontal 24-hour air flow rates above 0.28 m·s−1 effectively reduced tipburn symptom, with no significant differences being found among the tested air flow rates, while above 65% of tipburned plants were found in the control plot of 0.08 m·s−1 flow rate. When stable air flow was applied, compared to the control, there was an increase in the absolute calcium content and a decrease in the calcium content difference between the inner and outer lettuce leaves. This calcium balance change may have occurred due to the enhanced transpiration in the inner parts of plants. This study showed that stable horizontal air flow application along cultivation beds is more effective than air temperature control in decreasing tipburn symptoms in a closed plant factory system.

Predictability of soil succession patterns under different agricultural land use practices: Continual conventional cultivation versus transformation to organic cultivation or fallow periods

Abstract Changes in agricultural management practices create conditions that directly or indirectly promote the onset of secondary succession processes in the soil. Previous research has demonstrated that the succession of temperate forests follows the Markov principle, which states that the next state of a process depends only on the preceding state; hence, we set out to test this principle for soils subjected to different land uses over a 2 year period. Specifically, (1) continued conventional cultivation (i.e. the monoculture of shell beans, Phaseolus vulgaris L., with chemical fertilisers); (2) transformation of land-use from conventional cultivation to organic cultivation (shell beans fertilised with manure); and (3) transformation of land-use to a fallow state. The soil was sampled three times at specific shell bean growth stages (June, the seedling stage; August, mid-growth; October, one month after harvest) in both years, with various chemical and biochemical soil profiles being conducted (including carbon, nitrogen and phosphorus levels, and enzymatic activity). Correlations among successive soil chemical and biochemical profiles were stronger (two successive events: June and August, August and October) in the first year compared to the second year (one successive event: August and October) for the organic plots. For soils in which conventional land management was continued, significant correlation was only detected for one successive profile (August–October) in both years, whereas no significant correlation was obtained for any successive profiles in the fallow plots. Therefore, the Markov principle only holds for the entire cultivation period under certain conditions for bean crops; specifically, initial conventional cultivation followed by transformation to organic cultivation. In the case of continued conventional monoculture, the Markov principle is partially supported. In contrast, fallow plots did not follow any predictable pattern of changes in soil chemical and biochemical profiles. In conclusion, agricultural management causes soil succession processes to be predictable, due to the environmental homogeneity induced by manure and/or the limited plant effect, rather than natural processes.

Growth stage specific optima for the green area index of winter wheat

High grain yields and high N use efficiency in cereals both rely on optimal canopy dynamics during the growth period. Target values of green area index (GAI) and, consequently, N uptake for specific growth stages (GS) may be a simple and practical approach for adjusting crop N management site and year specifically. Based on data from two field trials with widely differing N fertilization rates over a range of years and with a different number of varieties (Exp. 1: 2004–2007, one variety; Exp. 2: 2003, 2005–2008, four varieties), this study aims (i) to identify optimal GAI at different GS of winter wheat (estimated from the final grain yield using Linear-Plateau-response curves) and (ii) to test if these reference GAI values are sufficiently constant between years and varieties to be, in consequence, suitable to manage the wheat canopy.Optimal GAI increased during stem elongation, however, the correlation between GAI and yield often remained poor in early growth stages. In Exp. 1, optimal GAI at GS >31 differed between the years with values ≤3 in 2004 and 2007 and ≥4 in 2005 and 2006. In Exp. 2, considerable differences between the tested varieties could be observed. In general, it was not possible to consistently relate the optimal GAI course during spring to growth stages. An optimal GAI course for winter wheat, as a simple guideline for the N management, seems to be no promising approach for the conditions tested.

Optimizing Deficit Irrigation Scheduling Under Shallow Groundwater Conditions in Lower Reaches of Amu Darya River Basin

Water demand for irrigated agriculture is increasing against limited availability of fresh water resources in the lower reaches of the Amu Darya River e.g., Khorezm region of Uzbekistan. Future scenarios predict that Khorezm region will receive fewer water supplies due to climate change, transboundary conflicts and hence farmers have to achieve their yield targets with less water. We conducted a study and used AquaCrop model to develop the optimum and deficit irrigation schedule under shallow groundwater conditions (1.0–1.2 m) in the study region. Cotton being a strategic crop in the region was used for simulations. Capillary rise substantially contributes to crop-water requirements and is the key characteristic of the regional soils. However, AquaCrop does not simulate capillary rise contribution, thereby HYDRUS-1D model was used in this study for the quantification of capillary rise contribution. Alongside optimal irrigation schedule for cotton, deficit strategies were also derived in two ways: proportional reduction from each irrigation event (scenario-A) throughout the growth period as well as reduced water supply at specific crop growth stages (scenario-B). For scenario-A, 20, 40, 50 and 60 % of optimal water was deducted from each irrigation quota whereas for scenario-B irrigation events were knocked out at different crop growth stages (stage 1(emergence), stage 2 (vegetative), stage 3 (flowering) and stage 4 (yield formation and ripening)). For scenario-A, 0, 14, 30 and 48 % of yield reduction was observed respectively. During stress at the late crop development stage, a reduced water supply of 12 % resulted in a yield increase of 8 %. Conversely, during stress at the earlier crop development stage, yield loss was 17–18 %. During water stress at the late ripening stage, no yield loss was observed. Results of this study provide guidelines for policy makers to adopt irrigation schedule depending upon availability of irrigation water.

Grapevine recovery from saline irrigation was incomplete after four seasons of non-saline irrigation

Crop exposure to salinity can be episodic. The effects on the crop are the sum of those manifest whilst stress establishes, persists and abates. This paper reports on the response of grapevines during stress abatement. It follows from Stevens et al. (2011a) which reported on the response over three consecutive seasons of Colombard vines (Vitis vinifera) on Ramsey rootstock (Vitis champinii) to irrigation with saline water (ECi 3.5dS/m) during specific growth stages, and with non-saline water (ECi 0.5dS/m) during the rest of the season. Over the next four seasons all vines were irrigated with non-saline water (ECi 0.4dS/m). The current paper characterises recovery during this period using key traits including growth, yield and concentrations of Na+ and Cl− in root and leaf lamina. By harvest in the second season following cessation of saline irrigation, the soil salinity and leaf lamina Na+ and Cl− concentrations in previously salinised vines had fallen below the levels associated with salinity-induced yield loss. Maximum yield loss of 22% averaged over the four seasons was higher than the maximum of 15% during saline irrigation. Yield losses were associated with loss of berry weight. Following cessation of saline irrigation, a reduction in bunch numbers caused an additional yield loss. A reduction in pruning weights did not emerge until after saline irrigation ceased. Salinity's sting can be in its tail. Losses of yield, bunch number and pruning weight were independent of season, whilst those in berry weights diminished over the four seasons. In the last two seasons, yield loss could not be attributed to osmotic or toxic effects of salinity. Another unidentified effect of salinity was stressing the vines.

Improving evapotranspiration simulations in the CERES-Maize model under limited irrigation

Limitations on water resources for agriculture in places such as Colorado, USA, have caused farmers to consider limited irrigation as an alternative to full irrigation practices, where the crop is intentionally stressed during specific growth stages in an effort to maximize yield per unit water consumed, or evapotranspiration (ET). While crop growth models such as CERES-Maize provide the ability to evaluate numerous management scenarios without the costs associated with multiyear field experiments, recent studies have shown that CERES-Maize performs well under full irrigation but overestimates ET of corn under limited irrigation management. The primary objective of this study was to improve CERES-Maize ET simulation under limited irrigation management while maintaining accuracy of other important model output responses. Field experiments with corn were performed in northern Colorado, USA from 2006 to 2010, where four replicates each of full (ET requirement supplied by irrigation throughout the season) and limited (no irrigation before the V12 growth stage unless necessary for emergence, then full irrigation afterwards) irrigation treatments were analyzed. The local sensitivity of model input parameters affecting ET was evaluated, prompting changes to the model code with a new dynamic crop coefficient (KCD) as a function of the crop leaf area index. The modified CERES-Maize model more accurately represented ET under full and limited irrigation, for example reducing late-season ET potential from a plant with reduced canopy and more closely matched FAO-56 crop coefficient curves under full irrigation. Using the limited irrigation data for evaluation, the modified model showed significant decreases in model error for seasonal cumulative ET (root mean square deviation RMSD from 80.9mm to 49.9mm) and water productivity (RMSD from 5.97kgha−1mm−1 to 2.86kgha−1mm−1) as compared to the original model. The modified model was subsequently applied to several hypothetical irrigation management strategies, indicating that reducing weekly vegetative stage water applications from 20mm to 2.5mm can increase simulated water productivity by over 15%. While these synthetic water production functions may not be feasible in a production field with natural climate variability, the modified ET model indicates promise for limited irrigation management increasing water productivity.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF CITRUS (CITRUSSPP.): A REVIEW

SUMMARYThe results of research on the water relations and irrigation need ofCitrusspp. are collated and reviewed in an attempt to link fundamental studies on crop physiology to drought mitigation and irrigation practices. Background information is given on the centres of origin (south-east Asia) and of production of citrus (areas with subtropical Mediterranean-type climates). The effects of water stress on the development processes of the crop are summarised followed by reviews of the plant water relations, crop water requirements, water productivity and irrigation systems. The topic is complicated by the diversity of species and cultivars (including rootstocks) that are embraced withinCitrusspp. The effects of water availability on vegetative growth are understood in general terms, but the relationships have not yet been quantified. Similarly, the need for a ‘rest period’ to induce flowering is understood, but its magnitude (in terms of a drought stress index or day-degrees) does not appear to have been specified with precision. Again, the effects of drought on flower and fruit formation and retention are understood in general terms, but the relationships have not been quantified in useful ways for specific cultivars. Rooting depth and distribution have only been described in a limited number of situations. Environmental factors influencing stomatal conductances are generally well described and relationships with some growth processes established. Compared with other crops, low stomatal/canopy conductance restricts water use ofCitrusspp. Some (limited) progress has been made in quantifying crop water requirements in specific conditions. Despite many recent attempts to specify how little water can be applied at specific growth stages to optimise water productivity through regulated deficit irrigation, no consensus view has emerged. The yield response to ‘full’ irrigation is of the order 6–7 kg fresh fruit m−3as a result of an increase in the number of fruit of marketable size. There are also improvements in fruit quality. The most effective way of irrigating a citrus orchard is with a microirrigation system (drip or microsprinklers), but both methods require answers to the question: what proportion of the root zone needs to be irrigated? Both methods, especially drip, allow water to be applied (with fertigation) at very frequent intervals (including several times a day), although formal evidence of the benefits to be obtained from this level of intensification is lacking.

SPM43.1 Contributes to Acid-Resistance of Non-Symplasmata-Forming Cells in Pantoea agglomerans YS19

Pantoea agglomerans YS19 is a rice endophytic bacterium characterized to form multicellular biofilm-like structures called symplasmata. Phenotypic distinctions between symplasmata-forming cells and planktonic cells are crucial for understanding YS19's survival strategies. In this study, a 43.1kDa protein SPM43.1 was identified to show significant resistance to the aggregation effect caused by denaturing acidic conditions. MALDI-TOF analysis data indicated that it is a maltose-binding protein homolog while contains sequence homologous to the chaperone protein, ClpB. The purified SPM43.1 protein was detected to exhibit chaperone-like activities at acidic conditions, where its conformation transformed from an ordered to a globally less ordered structure as revealed by circular dichroism spectroscopy, showing a similar property to most chaperone proteins. The expression of SPM43.1 in YS19 is initiated when bacterial cells begin to aggregate, yet its amount in planktonic cells greatly exceeds that in symplasmata-forming cells, suggesting its crucial role to the survival of planktonic cells in experiencing environmental fluctuations. However, the bacterium prefers to form symplasmata, while not to express SPM43.1 proteins, for surviving the artificially set fluctuant (acid here) environments. This study provides valuable information on the life styles and survival strategies of microorganisms that forms multicellular aggregates at specific growth stages.

Abstract 3475: Tumor stage dependent contribution of bone marrow derived cells to tumor neo-vascularization

Abstract Introduction: The role of bone marrow derived cells (BMDC) in tumor neo-vascularization remains controversial. We have previously demonstrated that BMDC contribute to tumor neovascularization by differentiating into vascular support cells and not endothelial cell. In this study we focus on establishing the spatiotemporal role of BMDC in tumor neovascularisation, focusing on whether it is a tumor growth stage dependent process and more specifically examining the patterns of BMDC integration into tumor vasculature in response to radiation therapy (RTx). Methods: Animal Models: Bone marrow of NOD/SCID mice were stably reconstituted with BM harvested from green-fluorescent protein (GFP) transgenic mice. Intracranial (ic) xenografts were generated in intracranial window models (ICW) using a panel of glioma cell and breast cancer cells stably expressing mCherry. In-vivo imaging: Two-photon laser capture microscopy was used to obtain high-resolution real-time in-vivo longitudinal images of the tumor cells, tumor vasculature and tracing of the circulating GFP+BM cells. Mice were imaged 1d,2d,3d,7d,10d,14d,21d & 30d following cell implantation or RTx. Brain Tumor Analysis: Mice were sacrificed using perfusion fixation and brains collected for correlative immunohistochemical and Immunofluorscent confocal analysis. RTx: Using in-house designed x-ray micro-irradiator stereotactic radiation was delivered through ICW to ic-xenografts, treated with either 3×2Gy or 3×5Gy. Tumor+RTx was compared to RTx alone or tumor alone (n=15 each arm). Results: At early stages of tumor formation (<1wk) there is 90% integration of BMDC into the tumor vasculature, while to late stages of tumor growth (>2 wks) only 10% integration of BMDC is seen. At later stages of tumor growth (>2 wks) BMDC incorporation in the tumor vasculature is predominantly seen in the tumor periphery compared to the tumor centre, with the peripheral vessels demonstrating almost 100% integration of BMDC compared to the centre of the tumor where the vasculature have no integration of BMDC. Conclusions: Our results are the first to demonstrate that there is a specific tumor growth stage dependent contribution of BMDC to tumor neo-vascularization. At early stages of tumor growth neo-ascularization relies on host BMDC, while at later stages of tumor growth vascularization relies on branching of pre-existing vessels. A significant difference in extent of BMDC integration is noted between periphery versus the centre of the tumor, suggesting that the internal tumor micro-environment regulates neoascularization differently from the periphery. Intriguingly, this distinction is not seen with tumor neovascularization in recurrent tumors following RTx. These results have significant therapeutic implications and point to a need for scheduling of anti-angiogenic therapies according to tumor growth stage and timing post RTx. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3475. doi:10.1158/1538-7445.AM2011-3475

Effect of Nod factor sprays on soybean growth and productivity under field conditions

A field experiment was conducted at Ste. Anne de Bellevue, Quebec during the growing seasons of 2002 and 2003, to study the effect of Nod factor treatments, applied at specific growth stages, on photosynthesis and biomass accumulation by soybean grown under two tillage systems (conventional tillage, no-tillage). Spray application of Nod factors increased photosynthesis at the four fully expanded trifoliate leaves and full bloom growth stages under no-tillage and conventional tillage; they increased plant biomass at the beginning seed filling stage. Nod factor treatment did not affect yield in 2002, due to severe drought during the reproductive period. In 2003, Nod factor application increased yield under conventional tillage but not under no-tillage, and this may have been due to the negative effect of no-tillage on plant growth on the clay-loam soil at the experimental site. This study indicated that responses to Nod factors are affected by environmental conditions, and that Nod factors may be useful when applied to soybean grown under conventional tillage.

Using Soil Plant Analysis Development Chlorophyll Meter for Two Growth Stages to Assess Grain Yield of Malaysian Rice <i>(Oryza sativa)</i>

Problem statement: Proper yield management in rice influences grain quality and quantity. Nitrogen site-specific management is also effective on final product of crops because excessive nitrogen application at any growth stage can reduce yield and increase disease incidence. In contrast, suboptimal nitrogen levels at discrete growth stages may substantially reduce plant productivity. The nitrogen status at specific growth stages may be used for estimating supplemental nitrogen requirements and yield potential. The SPAD chlorophyll meter is a quick and non-destructive tool used for directly measuring leaf chlorophyll and indirectly assessing the proportional parameter of leaf, plant nitrogen status and finally, grain yield. Approach: Describing within-field variability in a typical Malaysian paddy field was conducted to show the temporal variability of SPAD readings and also grain yield. Furthermore, the study aimed to introduce the rice growth stage which SPAD readings show higher relationship with grain yield. SPAD readings data was collected at two different growth stages (55 DAT and 80 DAT) using a Minolta SPAD 502. Grain yield was then collected at the end of the season to compare results with SPAD values. Results: Analysis of variance, variogram and kriging were conducted to determine the variability of parameters and also their relationship. Conclusion: Variability maps of the aforementioned parameters were generated. Increasing of SPAD values with growth stage could be observed in this study. SPAD readings taken at 55 DAT had a better relationship to grain yield than those taken at 80 DAT; therefore assessment of grain yield status is better to be done at 55 DAT.