Non-irrigated Research Articles

Influence of non-irrigation and seasonality on wine colour, phenolic composition and sensory quality of a grapevine (<i>Vitis vinifera</i> cv. Callet) in a Mediterranean climate

Most vineyards in Mediterranean areas are cultivated using a training system and drip irrigation. However, the increasing risk of water deficit stress due to global warming will mean that viticulture need to adapt to a tougher water-saving policy. Thus, we investigated the effects of total suppression of irrigation on a grapevine (Vitis vinifera cv. Callet) and the phenolic composition and sensory quality of this native red variety wine from the Balearic Islands over three seasons. Significant yield reductions of up to 15.6 %, 17.2 % and 22.2 % were observed in non-irrigated (NI) plants in 2016, 2017 and 2018 respectively, compared to irrigated plants (I); however, wine quality parameters improved. In the years with the highest rainfall (715 mm in 2016 and 799 mm in 2017), NI favoured the enrichment of sugars, anthocyanins and phenolic compounds in the wine and enhanced the development of aromatic components. However, with lower rainfall (524 mm in 2018), the NI treatment appeared to diminish the quality of the wine, particularly affecting the global sensory quality of the wines. Thus, development of specific water strategies tailored to the vineyard, year, vintage and grape variety may regulate the phenolic composition of red wines to meet production goals and reduce total water consumption.

Catheter ablation of atrioventricular nodal reentrant tachycardia with an irrigated contact-force sensing radiofrequency ablation catheter.

Radiofrequency ablation (RFA) slow pathway modification for catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) is traditionally performed using a 4-mm nonirrigated (NI) RF ablation catheter. Slow pathway modification using irrigated, contact-force sensing (ICFS) RFA catheters has been described in case reports, but the outcomes have not been systematically evaluated. Acute procedural outcomes of 200 consecutive patients undergoing slow pathway modification for AVNRT were analyzed. A 3.5-mm ICFS RFA catheter (ThermoCool SmartTouch STSF, Biosense Webster, Inc.) was utilized in 134 patients, and a 4-mm NI RFA catheter (EZ Steer, Biosense Webster, Inc.) was utilized in 66 patients. Electroanatomic maps were retrospectively analyzed in a blinded fashion to determine the proximity of ablation lesions to the His region. The baseline characteristics of patients in both groups were similar. Total RF time was significantly lower in the ICFS group compared to the NI group (5.53 ± 4.6 vs. 6.24 ± 4.9 min, p = 0.03). Median procedure time was similar in both groups (ICFS, 108.0 (87.5-131.5) min vs. NI, 100.0 (85.0-125.0) min; p = 0.2). Ablation was required in closer proximity to the His region in the NI group compared to the ICFS group (14.4 ± 5.9 vs. 16.7 ± 6.4 mm, respectively, p = 0.01). AVNRT was rendered noninducible in all patients, and there was no arrhythmia recurrence during follow-up in both groups. Catheter ablation was complicated by AV block in one patient in the NI group. Slow pathway modification for catheter ablation of AVNRT using an ICFS RFA catheter is feasible, safe, and may facilitate shorter duration ablation while avoiding ablation in close proximity to the His region.

Quality of cold stored lemon fruit from orchards consociated to ancient olive trees

In the hilly area of Gioia Tauro (Calabria, Southern Italy), lemon orchards are grown in consociation with centuries-old olive trees. Lemons are partially shaded by olive canopies and the microclimate at the level of their canopies is suitable for plants growth and quality productions. Under these conditions, lemon trees are grown even without irrigation, providing, despite this limitation, a quality product. This study aimed to i) investigate the qualitative characterisation of two clonal selections of the lemon cultivar Femminello, F. Siracusano (S) and F. Zagara bianca (ZB), from the described intercropping, on irrigated (I) and non-irrigated (NI) crops; ii) assess the quality preservation during cold storage, in order to evaluate the availability of lemons for marketing in a period of shortage such as the summer season. Fruits were harvested at commercial maturity, and cold stored at 10±1°C and RH 85-90%, for 60 days. Decay incidence, physiological disorders, weight loss, and the main physical-chemical parameters were assessed at harvest (T0) and every 15 days (T15, T30, T45, T60). The absence of decay and physiological disorders was observed throughout the 60-day storage period, in both clonal selections under the two management conditions. The weight loss was greater in fruits from irrigated lemon groves of both S and ZB. S_I showed significantly lower fruits weight and higher titratable acidity than S_NI. Total soluble solids and titratable acidity were statistically lower for ZB_I than for NI fruits.

Soybean Seed Sugars: A Role in the Mechanism of Resistance to Charcoal Rot and Potential Use as Biomarkers in Selection.

Charcoal rot, caused by Macrophomina phaseolina, is a major soybean disease resulting in significant yield loss and poor seed quality. Currently, no resistant soybean cultivar is available in the market and resistance mechanisms to charcoal rot are unknown, although the disease is believed to infect plants from infected soil through the roots by unknown toxin-mediated mechanisms. The objective of this research was to investigate the association between seed sugars (sucrose, raffinose, stachyose, glucose, and fructose) and their role as biomarkers in the soybean defense mechanism in the moderately resistant (MR) and susceptible (S) genotypes to charcoal rot. Seven MR and six S genotypes were grown under irrigated (IR) and non-irrigated (NIR) conditions. A two-year field experiment was conducted in 2012 and 2013 at Jackson, TN, USA. The main findings in this research were that MR genotypes generally had the ability to maintain higher seed levels of sucrose, glucose, and fructose than did S genotypes. Conversely, susceptible genotypes showed a higher level of stachyose and lower levels of sucrose, glucose, and fructose. This was observed in 6 out of 7 MR genotypes and in 4 out of 6 S genotypes in 2012; and in 5 out of 7 MR genotypes and in 5 out of 6 S genotypes in 2013. The response of S genotypes with higher levels of stachyose and lower sucrose, glucose, and fructose, compared with those of MR genotypes, may indicate the possible role of these sugars in a defense mechanism against charcoal rot. It also indicates that nutrient pathways in MR genotypes allowed for a higher influx of nutritious sugars (sucrose, glucose, and fructose) than did S genotypes, suggesting these sugars as potential biomarkers for selecting MR soybean plants after harvest. This research provides new knowledge on seed sugars and helps in understanding the impact of charcoal rot on seed sugars in moderately resistant and susceptible genotypes.

Row spacing and irrigation management affect soybean yield, water use efficiency and economics

Declining water levels in the Mississippi River Valley Alluvial Aquifer necessitates research on the management practices that can reduce irrigation water use and improve irrigation water use efficiency. A three-year field study from 2019 to 2021 evaluated the effects of row spacing and irrigation management on soybean seed yield and quality, irrigation water use efficiency (IWUE), water productivity (WP), and profitability. Soybean was planted in two row spacings [single- (SR) and twin-row (TR)] and irrigated with three different methods [every row irrigated (ERI), alternate row irrigated (ARI), non-irrigated (NI)]. Soybean yields were increased with application of irrigation either as ERI or ARI as compared to NI in all three years ranging from 20% to 79%. The ERI had 20% increase in yield over ARI in 2021, whereas no significant differences were found between ERI and ARI in 2019 and 2020. Averaged over row spacing, IWUE was 66–91% greater with ARI compared to ERI. Only 2021 showed an increase (34%) in WP with irrigation applied as ARI than NI. Differences in rainfall amount among years and amount of irrigation applied under different treatments affected the soybean yields. Soybean yield showed reduction by 0.37–1.2 kg ha−1 with each unit increase in cumulative stress (kPa-days) for soil moisture potential drier than the −40 kPa on very fine sandy loam soils. Twin-row soybean had higher expected returns in all cases except for the NI and ERI in 2021. The TR soybean produced the greatest average risk-return than other treatments. The ARI with TR had the second highest overall risk-return trade-off. The ARI resulted in an equivalent risk-return production system as ERI for SR soybeans. Alterations in furrow irrigation methods could be more beneficial than row spacing to improve soybean productivity and IWUE.

Bayesian modeling of the coffee tree growth curve

ABSTRACT: When modeling growth curves, it should be considered that longitudinal data may show residual autocorrelation, and, if this characteristic is not considered, the results and inferences may be compromised. The Bayesian approach, which considers priori information about studied phenomenon has been shown to be efficient in estimating parameters. However, as it is generally not possible to obtain marginal distributions analytically, it is necessary to use some method, such as the weighted resampling method, to generate samples of these distributions and thus obtain an approximation. Among the advantages of this method, stand out the generation of independent samples and the fact that it is not necessary to evaluate convergence. In this context, the objective of this work research was: to present the Bayesian nonlinear modeling of the coffee tree height growth, irrigated and non-irrigated (NI), considering the residual autocorrelation and the nonlinear Logistic, Brody, von Bertalanffy and Richard models. Among the results, it was found that, for NI plants, the Deviance Information Criterion (DIC) and the Criterion of density Predictive Ordered (CPO), indicated that, among the evaluated models, the Logistic model is the one that best describes the height growth of the coffee tree over time. For irrigated plants, these same criteria indicated the Brody model. Thus, the growth of the non-irrigated and irrigated coffee tree followed different growth patterns, the height of the non-irrigated coffee tree showed sigmoidal growth with maximum growth rate at 726 days after planting and the irrigated coffee tree starts its development with high growth rates that gradually decrease over time.

Soil Respiration Characteristics and Influencing Factors for Apple Orchards in Different Regions on the Loess Plateau of Shaanxi Province

To explore the characteristics of the spatial and temporal variation in soil respiration (SR) in orchard ecosystems in different regions of the Loess Plateau of Shaanxi Province and to distinguish the controlling factors, representative orchards were studied from April to October 2019. We conducted SR measurements in five locations, including Mizhi dangta (MZ), Ansai Liuzhuang (AS), Luochuan houzitou (LC), Fuping meijiaping (FP), and Yangling Wuquan (YL). The results indicated that the SR of each orchard showed clear seasonal variation. The SR increased with the distance from the trunk at the tree scale, while gradually increasing from north to south on the regional scale (p < 0.05). The soil temperature and soil moisture were the main factors controlling the seasonal changes in SR in the orchards. On the tree scale, the fine root biomass was the main factor causing the tree-scale spatial variability. At the regional scale, SR was mainly influenced by the differences in the soil temperature, soil moisture, soil organic carbon, soil bulk density and pH. In agricultural management practices, the cumulative soil respiration was higher with irrigated treatment than with non-irrigated (NI) treatment (p < 0.05). In addition, traditional surface drip irrigation (SDI) and root injection irrigation (RII) showed great differences in soil respiration in the early and late stages of irrigation (p < 0.05), and the soil moisture was the main controlling factor. Compared with no tillage (NI), green cover (GC), deep tillage (DT), and shallow tillage (ST) increased the SR by 57%, 36% and 14%, respectively (p < 0.05). Due to the great temporal and spatial variation in the SR in our study area, we determined that the soil respiration in the orchards was affected not only by environmental factors but also by agricultural measures. Therefore, greater attention should be paid to human factors when exploring SR to ensure that orchard management can promote the economic benefits of the orchards without greatly impacting the environment.

Yield Prediction in Soybean Crop Grown under Different Levels of Water Availability Using Reflectance Spectroscopy and Partial Least Squares Regression

Soybean grain yield has regularly been impaired by drought periods, and the future climatic scenarios for soybean production might drastically impact yields worldwide. In this context, the knowledge of soybean yield is extremely important to subsidize government and corporative decisions over technical issues. This paper aimed to predict grain yield in soybean crop grown under different levels of water availability using reflectance spectroscopy and partial least square regression (PLSR). Field experiments were undertaken at Embrapa Soja (Brazilian Agricultural Research Corporation) in the 2016/2017, 2017/2018 and 2018/2019 cropping seasons. The data collected were analyzed following a split plot model in a randomized complete block design, with four blocks. The following water conditions were distributed in the field plots: irrigated (IRR), non-irrigated (NIRR) and water deficit induced at the vegetative (WDV) and reproductive stages (WDR) using rainout shelters. Soybean genotypes with different responses to water deficit were distributed in the subplots. Soil moisture and weather data were monitored daily. A total of 7216 leaf reflectance (from 400 to 2500 nm, measured by the FieldSpec 3 Jr spectroradiometer) was collected at 24 days in the three cropping seasons. The PLSR (p ≤ 0.05) was performed to predict soybean grain yield by its leaf-based reflectance spectroscopy. The results demonstrated the highest accuracy in soybean grain yield prediction at the R5 phenological stage, corresponding to the period when grains are being formed (R2 ranging from 0.731 to 0.924 and the RMSE from 334 to 403 kg ha−1—7.77 to 11.33%). Analyzing the three cropping seasons into a single PLSR model at R5 stage, R2 equal to 0.775, 0.730 and 0.688 were obtained at the calibration, cross-validation and external validation stages, with RMSE lower than 634 kg ha−1 (13.34%). The PLSR demonstrated higher accuracy in plants submitted to water deficit both at the vegetative and reproductive periods in comparison to plants under natural rainfall or irrigation.

Supplemental irrigation to save water while growing cactus pear in semi‐arid regions*

AbstractClimate change will compromise food access by causing water shortages for agricultural purposes. Supplemental irrigation (SI) was explored for its effect on crop water use, fruit yield, water use efficiency, water productivity, mean fruit mass and fruit size distribution of four cactus pear cultivars. The irrigation treatments were: non‐irrigated (NI) rainfed control, SI and full irrigation (FI). The cultivars were: ‘Cristalina’ (Opuntia albicarpa Scheinvar), ‘Amarilla Olorosa’ (O. spp.), ‘Roja Lisa’ (O. ficus‐indica L. Mill.), and ‘Dalia Roja’ (O. spp.). The experiment was conducted in a split‐block design. The SI treatment saved water, in a 3‐year‐average, by 52% for ‘Cristalina’, 51% for ‘Roja Lisa’ and 52% for both ‘Amarilla Olorosa’ and ‘Dalia Roja’. This resulted in a reduction in crop water use by 38% for ‘Cristalina’, 42% for ‘Roja Lisa’, 39% for ‘Amarilla Olorosa’ and 40% for ‘Dalia Roja’. For SI, plant‐relative water content and fruit growth were similar to the FI plants. SI plants maintained fruit yield, mean fruit mass and marketable fruit size at the level of FI plants, while it improved efficiencies of water use and water productivity. SI is therefore a feasible irrigation strategy for cactus pear for those areas where water availability is limited for agricultural activities.

Water status response of pineapple using destructive and non-destructive indicators and their relations in two contrasting seasons

Abstract The use of indicators to assess the water status of pineapple grown inside greenhouses is essential to obtain higher yields. Although destructive and non-destructive indices are widely applied to monitor several crops, there are no previous reports that evaluate their response to different seasons or the relationship between the indicators and the water status of pineapple plants. The experiment was conducted during the warm and cold seasons, comparing two treatments: plants irrigated to field capacity (FC) and non-irrigated (NI). The water status was measured using a destructive index, Relative Water Content (RWC), and non-destructive indices, Normalized Difference Vegetation Index (NDVI), and Stress Degree Day (SDD). The environmental conditions monitored were temperature, humidity, and photosynthetically active radiation (PAR). At the end of each season, plant biomass and assimilate partitioning (AP) were also determined. The recovery of the NI treatment by irrigation was measured using NDVI and RWC. In the cold season, differences between treatments were detected after 45 days of water restriction by NDVI, while in the warm season, the RWC index found differences a week after the experience began (p

Quality and storability of cactus pear fruit as improved by supplemental irrigation

This research evaluated some fruit quality attributes at harvest and after two storage conditions [i.e., room temperature and cold storage] of four cactus pear cultivars previously exposed to non-irrigated (NI) treatment as the control, supplemental irrigation (SI) and commercial irrigation (CI). The cultivars responded differently to irrigation treatments and among evaluations. SI and CI plants had the highest fruit and pulp mass at harvest and maintained at both storage conditions, although these results were not always significant. Flesh firmness tended to be the highest in SI and CI fruit at harvest in all cultivars. The latter response was maintained occasionally at both storage conditions in all cultivars. Both dry mass concentration and total soluble solids concentration tended to be the highest in NI fruit of all cultivars. Fruit mass loss was minimized by SI and CI treatments in both storage conditions, and in relation to room temperature storage, cold storage increased the fruit storage life of all cultivars. At the start of the experiment, NI fruit at room temperature storage had the highest decay incidence; after that, this fruit deterioration problem was observed occasionally in both storage conditions. It was concluded that the amount and occurrence of rain was an important factor in the statistical inconsistence of the response variables. However, the SI and CI treatments minimized fruit mass loss in both storage conditions and extended the fruit storage life of all cultivars in cold storage, which is important for transportation, marketing, and consumers. Additionally, SI, on a three-year-average, saved irrigation water by 51% compared to CI, therefore, SI may be recommended to similar agro-ecological regions.

Endophytic diazotrophic bacteria mitigate water deprivation effects in pineapple explants during acclimatization

We examined physiological and growth promotion traits in water-deprived pineapple explants inoculated with two endophytic diazotrophic bacteria. The following questions were addressed: (i) Is the root inoculation efficient to increase bacteria population associated to pineapple explants? (ii) Are nutrient concentrations improved in pineapple explants in response to endophytic bacteria inoculation? (iii) Can endophytic bacteria improve pineapple explants’ growth and photosynthesis? (iv) Is it possible to mitigate water deprivation negative effects and facilitate pineapple explants’ acclimatization using endophytic diazotrophic bacteria? Pineapple ‘Vitoria’ explants grown in vitro were inoculated with two different bacteria species. Therefore, 10 mL of bacteria suspension (108 cells mL−1) of either Burkholderia silvatlantica strain UENF 117111 or Herbaspirillum seropedicae strain HRC54 were applied in the substrate after transplantation. Uninoculated explants received 10 mL of autoclaved DYGS liquid medium (Control treatment). These treatments were subdivided in two water regimes, so that explants were either full-irrigated (FI) or non-irrigated (NI) for 24 days. Thereafter, NI explants were re-irrigated to saturation for two days. We found that: (i) The inoculation was efficient to increase bacteria associated to the plantlets; (ii) Nutrient concentrations were not improved in pineapple explants inoculated with both bacteria species; (iii) B. silvatlantica did not change both growth and photosynthetic capacity of the explants. Nonetheless, H. seropedicae inoculation caused negative effects on growth, whereas Anet was increased; (iv) The use of both bacteria delayed water deprivation effects and maintained the photosynthetic capacity through C3 metabolism intact for longer periods under water deprivation, as well as by recovering Anet after re-irrigation.

Water and Nitrogen Budget Dynamics for a Maize-Peanut Rotation in Florida

HighlightsDSSAT simulations of final N uptake, biomass, and yield for a maize-peanut rotational field experiment with three irrigation treatments and three N fertilizer rates had good performance for the irrigated treatments (average nRMSE of 9%) but greater error for the rainfed treatments (average nRMSE of 15%).Experiments and DSSAT simulations demonstrated that N fertilizer and irrigation applications were reduced by 26% and 60%, respectively, when using a 247 kg N ha-1 fertilizer rate and a sensor-based irrigation schedule rather than conventional practices of 336 kg N ha-1 and a calendar-based irrigation method, with no impact on yield.Simulations demonstrated that N leaching during the crop rotation was reduced by 37% when an N fertilizer rate of 247 kg N ha-1 and sensor-based irrigation scheduling were used versus conventional practices.Soil N increased (=15 mg kg-1) when maize and peanut residues decayed and then leached during the fallow season. Cover or cash crops planted immediately after the maize and peanut harvests have potential to take up this N and reduce leaching.Abstract. Nitrogen (N) is an essential element for crop growth and yield; however, excessive N applications not taken up by crops can result in N leaching from the root zone, increasing N loads to waterbodies and leading to a host of environmental problems. The main objective of this study was to simulate water and N balances for a maize-peanut (Zea mays L. and Arachis hypogaea L.) rotational field experiment with three irrigation treatments and three N fertilizer rates. The irrigation treatments consisted of mimicking grower irrigation practices in the region (GROW), using soil moisture sensors to schedule irrigation (SMS), and non-irrigated (NON). The N fertilizer rates were low, medium, and high (157, 247, and 336 kg N ha-1, respectively) for maize with a constant 17 kg ha-1 for all peanut treatments. DSSAT maize genetic coefficients were calibrated using the SMS-high treatment combination under the assumption of no water or N stress. The other eight treatment combinations were used as independent data for model validation of the crop coefficients. All soil hydrologic parameters were specified based on measured values, and default DSSAT peanut genetic coefficients were used with no calibration. For the irrigated treatments, DSSAT models had good performance for N uptake, biomass, and yield (average nRMSE of 8%) and moderate performance for soil water content (average nRMSE of 18%). Soil nitrate RMSE was 21% lower than the standard deviation of the observed data (5.8 vs. 7.2 mg kg-1). For the rainfed treatments, DSSAT had greater error (average nRMSE of 15% for N uptake, biomass, and yield, and average nRMSE of 31% for soil water). Soil nitrate RMSE was 11% greater than the standard deviation of the observed data (8.0 vs. 7.2 mg kg-1), and nRMSE was >30% during the crop rotation. Simulations estimated that N leaching over the crop rotation was reduced by 24% on average when using the 247 kg N ha-1 fertilizer rate compared to 336 kg N ha-1 across the irrigation treatments. Furthermore, N leaching was reduced by 37% when using SMS to schedule irrigation and the 247 kg N ha-1 fertilizer rate for maize and 17 kg N ha-1 for peanut compared to conventional practices (GROW and 336 kg N ha-1 for maize and 17 kg N ha-1 for peanut). Moreover, this management practice reduced N fertilizer use by 26% and irrigation water use by up to 60% without negative impacts on yield. Observed and simulated soil N increased during maize and peanut residue decay, with simulations estimating that this soil N would leach below the root zone during the fallow season. This leaching could potentially be reduced if a cover crop or cash crop were planted between the maize and peanut crops to take up the mineralized N. Keywords: Agricultural best management practices, Bare fallow, BMPs, Maize-peanut rotation, N balance, N fertilization, N leaching, Sandy soils, Sensor-based irrigation scheduling, Water balance.

Supplemental irrigation improves water-use efficiency, yield, and some fruit quality attributes of ‘Dalia Roja’ cactus pear

Cactus pear is grown mainly under rain-fed conditions in marginal semi-arid and arid highlands of central and north-central Mexico. Drip irrigation may increase fruit yield ~3.5-fold. However, the effects of supplemental irrigation (SI) on preharvest growth and water saving have not been assessed previously. The objective of this study was to determine the possibility of saving water and improving water-use efficiency (WUE) in 'Dalia Roja' cactus pear, without adverse effects on fruit yield (FY) and fruit quality (FQ). Irrigation treatments (IT) were as follows: non-irrigated (NI) as control, supplemental irrigation (SI), and full irrigation (FI). Treatments were arranged in a completely randomized design with three replicates. The response variables were irrigation water applied (IWA), WUE, FY, fruit size distribution (FSD), and FQ. The following FQ determinations were made: mean fruit mass (MFM), flesh firmness (FF), pulp and peel mass, total soluble solids concentration (TSSC), and dry matter concentration (DMC) of fruit. The experiment was conducted in Zacatecas, Mexico. At harvest, SI saved ~52% of IWA, increased the efficiency of IWA by ~1.4-fold, but reduced FY by 12.9% compared to FI. Over 70% of the fruit produced by FI and SI plants was most marketable (categories 1 and 2), while NI plants produced only 28% category 2 fruits. The quality indicators FF and pulp-to-peel ratio were similar among IT, while NI fruit had the highest TSSC and DMC and the lowest MFM. SI produced similar responses to FI while saving irrigation water and enhancing FY, FSD, and MFM, but TSSC and DMC were reduced. Nevertheless, SI has potential for growing cactus pear in this region and similar production zones around the world where water availability is limited.

Anthocyanin content and composition in four red winegrape cultivars (Vitis vinifera L.) under variable irrigation

Aim: The aim of this study was to determine and compare anthocyanin content and profile under variable irrigation regimes in four red grape cultivars (Vitis vinifera L.), the Greek indigenous cvs. Agiorgitiko and Xinomavro, alongside Syrah and Grenache noir.Methods and results: Three irrigation treatments were applied in a 6-year-old vineyard comprising all four varieties in a block design, starting at bunch closure (E-L 32) through harvest of 2012 and 2013: full irrigation (FI) at 100% of crop evapotranspiration (ETc), deficit irrigation (DI) at 50% of ETc and non-irrigated (NI). The identification of the compounds was performed by HPLC. Results showed that, under the hot summer conditions of the Greek climate, the four cultivars had a similar response regarding vigor and yield parameters, with values increasing with water supply. Anthocyanin concentration was maximized under non-irrigated conditions in all cultivars, but anthocyanin profile and relative distribution of individual anthocyanins among irrigation treatments showed a strong cultivar effect.Conclusion: Xinomavro seemed to favor the synthesis of more stable forms of anthocyanins under limited water supply (acylated over non-acylated and tri-oxygenated & methoxylated on the B-ring over di-oxygenated & hydroxylated) while Agiorgitiko had an opposite behavior, which might imply a need for a different irrigation strategy.Significance and impact of the study: To the best of our knowledge, this is the first comparative report of anthocyanin composition and profile in berry skin, under contrasting water status, for the two most important red winegrapes of Greece.

PHYSIOLOGY AND YIELD OF THREE SOYBEAN (GLYCINE MAX (L.) MERRILL) CULTIVARS DIFFERENT IN MATURITY TIMING AS AFFECTED BY WATER DEFICIENCY

Water deficiency is globally increasing as a direct result of climatic changes, threatening food production stability, especially of drought-susceptible crops, to which soybean (Glycine max (L.) Merrill) belongs. Soybean is mainly important because of its high protein and oil content. A field experiment was conducted in Debrecen, Hungary in 2017. Three soybean cultivars, different in maturity timing (very early-, early-, and middle-timing cultivars), were grown under two irrigation regimes; non-irrigated (NI) and fully-irrigated (FI) regime, in order to study the effect of water deficiency on the physiology and the yield of the above-mentioned cultivars. The yield of the three cultivars was increased when irrigation was applied, and though the increase was insignificant, yet the physiological traits were noticeably, and significantly in certain traits, different between the two irrigation regimes. It was concluded that water deficiency affects the physiology and the yield of soybean, and that the effect output is cultivar-dependent. More traits at different growth stages are needed to best understand water deficiency influence on soybean. Article DOI: https://dx.doi.org/10.20319/lijhls.2018.43.4659 This work is licensed under the Creative Commons Attribution-Non-commercial 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

Changes in Tannin Composition of Syrah Grape Skins and Seeds during Fruit Ripening under Contrasting Water Conditions.

Tannin accumulation and composition were determined in skins and seeds isolated from Vitis vinifera cv. Syrah grapes submitted to contrasting water regimes under semiarid climatic conditions. Three irrigation treatments were conducted, starting at berry set through harvest of two growing seasons, 2011 and 2012: irrigation at 100% of crop evapotranspiration ETc (FI), irrigation at 50% of ETc (DI) and non-irrigated (NI). Seed total tannins did not vary with maturity but those of skins underwent a progressive decline (especially in 2011), expressed both on a fresh weight and on a per berry basis. Skin total tannin concentration and content per berry were increased under NI and DI conditions, mainly in 2012. In contrast, seed total tannins (in 2012) and flavan-3-ol monomers and tannin oligomers (both years) were higher in the fully irrigated vines (FI). Skin polymer size increased during ripening, NI and DI skins showing higher mean degree of polymerization (mDP) compared to FI at harvest. NI was also associated with a lower percentage of galloylation (%G) in skin oligomeric fraction (in 2012) and a lower percentage of prodelphinidins in the skin polymeric fraction (both years) at harvest. The mDP and %G of seed extracts did not vary during ripening and were higher in NI but only in 2012. According to the results, management of vine water status was shown to influence tannin amount and composition of Syrah grapes grown under semiarid conditions.

Early Detection of Plant Physiological Responses to Different Levels of Water Stress Using Reflectance Spectroscopy

Early detection of water stress is critical for precision farming for improving crop productivity and fruit quality. To investigate varying rootstock and irrigation interactions in an open agricultural ecosystem, different irrigation treatments were implemented in a vineyard experimental site either: (i) nonirrigated (NIR); (ii) with full replacement of evapotranspiration (FIR); or (iii) intermediate irrigation (INT, 50% replacement of evapotranspiration). In the summers 2014 and 2015, we collected leaf reflectance factor spectra of the vineyard using field spectroscopy along with grapevine physiological parameters. To comprehensively analyze the field-collected hyperspectral data, various band combinations were used to calculate the normalized difference spectral index (NDSI) along with 26 various indices from the literature. Then, the relationship between the indices and plant physiological parameters were examined and the strongest relationships were determined. We found that newly-identified NDSIs always performed better than the indices from the literature, and stomatal conductance (Gs) was the plant physiological parameter that showed the highest correlation with NDSI(R603,R558) calculated using leaf reflectance factor spectra (R2 = 0.720). Additionally, the best NDSI(R685,R415) for non-photochemical quenching (NPQ) was determined (R2 = 0.681). Gs resulted in being a proxy of water stress. Therefore, the partial least squares regression (PLSR) method was utilized to develop a predictive model for Gs. Our results showed that the PLSR model was inferior to the NDSI in Gs estimation (R2 = 0.680). The variable importance in the projection (VIP) was then employed to investigate the most important wavelengths that were most effective in determining Gs. The VIP analysis confirmed that the yellow band improves the prediction ability of hyperspectral reflectance factor data in Gs estimation. The findings of this study demonstrate the potential of hyperspectral spectroscopy data in motoring plant stress response.

Characterization of Soybean Genetically Modified for Drought Tolerance in Field Conditions.

Drought is one of the most stressful environmental factor causing yield and economic losses in many soybean-producing regions. In the last decades, transcription factors (TFs) are being used to develop genetically modified plants more tolerant to abiotic stresses. Dehydration responsive element binding (DREB) and ABA-responsive element-binding (AREB) TFs were introduced in soybean showing improved drought tolerance, under controlled conditions. However, these results may not be representative of the way in which plants behave over the entire season in the real field situation. Thus, the objectives of this study were to analyze agronomical traits and physiological parameters of AtDREB1A (1Ab58), AtDREB2CA (1Bb2193), and AtAREB1 (1Ea2939) GM lines under irrigated (IRR) and non-irrigated (NIRR) conditions in a field experiment, over two crop seasons and quantify transgene and drought-responsive genes expression. Results from season 2013/2014 revealed that line 1Ea2939 showed higher intrinsic water use and leaf area index. Lines 1Ab58 and 1Bb2193 showed a similar behavior to wild-type plants in relation to chlorophyll content. Oil and protein contents were not affected in transgenic lines in NIRR conditions. Lodging, due to plentiful rain, impaired yield from the 1Ea2939 line in IRR conditions. qPCR results confirmed the expression of the inserted TFs and drought-responsive endogenous genes. No differences were identified in the field experiment performed in crop season 2014/2015, probably due to the optimum rainfall volume during the cycle. These field screenings showed promising results for drought tolerance. However, additional studies are needed in further crop seasons and other sites to better characterize how these plants may outperform the WT under field water deficit.

Molecular, physiological, and agronomical characterization, in greenhouse and in field conditions, of soybean plants genetically modified with AtGolS2 gene for drought tolerance

Water deficit may occur at any stage of crop development, affecting productivity and causing economic losses. In response to drought, raffinose family oligosaccharides (RFOs) are accumulated in plant tissues stabilizing and protecting cell membranes and keeping the vital functions. The enzyme galactinol synthase (GolS, EC 2.4.1.123) catalyzes the first step in the biosynthesis of RFOs. In our study, soybean events overexpressing 35S:AtGolS2 were molecularly, physiological, and agronomical characterized, under drought simulated in greenhouse and in field conditions during the crop season 2014/2015. The conventional soybean cultivar BRS 184 was transformed and five positive events were obtained. Four events transmitted the transgene to further generations and in the events 2Ia1 and 2Ia4, two to four copies of AtGols2 gene were observed. Results in greenhouse showed that the overexpression of AtGolS2 in genetically modified (GM) plants led to increased galactinol transcripts, probably resulting in changes in carbohydrate metabolism. Accumulation of these transcripts that may have acted as osmoprotectors, lead to higher drought tolerance and survival rate of 2Ia4 plants. In addition, in field conditions, higher yield was observed for 2Ia4 plants under irrigated (IRR) and non-irrigated (NIRR) treatments. This result can be due to the increased synthesis of RFOs even under well-watered conditions. This field screening showed promising results for drought tolerance, suggesting that 2Ia4 plants may be useful in a breeding program for the development of drought-tolerant plants. However, additional studies are needed in further crop seasons and other sites to better characterize how these plants may outperform the WT plants under water deficit.