Non-irrigated Treatment Research Articles

Citrus fruit yield response to nitrogen and potassium fertilization depends on nutrient-water management system

The objectives of the present study were to investigate the influence of water supply combined with different rates and methods of nitrogen (N) and potassium (K) application on fruit yield and nutrient use efficiency (NutUE) of citrus by monitoring plant nutritional status and soil solution dynamic. The experiment was carried out with 4-yr-old Natal sweet orange trees on Rangpur lime over 4 consecutive growing seasons. Treatments were composed of 2 rates of N and K (NK): 50% and 100% of the recommended rates for maximum yield in rain-fed environments and 3 nutrient-water management systems: non-irrigation + broadcast granular fertilizer, irrigation + broadcast granular fertilizer and fertilizer application via irrigation (fertigation). Fruit yield was maximum under fertigation with application of 50% of the NK rate, and fertigation improved NutUE by 22% compared to non-irrigated trees. However, no difference in productivity and NutUE occurred across nutrient-water management systems under 100% of the NK rate. Differences in plant nutritional were not consistent across treatments and did not contribute to explain variations in fruit yield and NutUE. Soil solution analysis of fertigated trees receiving 100% of the NK rate revealed the lowest pH value and the highest concentration of N-NH4. It is concluded that fruit yield responses of citrus trees treated with established NK rates for rain-fed environments might be limited by soil solution acidification and N-NH4 toxicity when fertilizers are applied via fertigation, being necessary further adjustments on fertilization management of fertigated citrus groves.

Scheduling deficit subsurface drip irrigation of apple trees for optimizing water use

The impact of four different irrigation strategies on soil and plant water status and fluxes of photosynthesis (A) and chamber transpiration (E) has been studied under continental climate on field-grown apple trees (Malus domestica ‘Gala’) in 2010 and 2011. The non-irrigated treatment resulted in a decrease in soil water content (SWC) throughout the season in comparison with irrigated treatments. Non-irrigated trees showed more negative values of predawn leaf water potential (ΨP), which decreased to − 0.2 MPa, reflecting a moderate water stress during the fruit ripening period. A decrease (15 to 25%) of stomatal conductance (gs), leaf photosynthesis (A), and transpiration (E) were observed in these water-stressed trees (T1). Well-irrigated trees during the whole season (T2) showed the highest rates of gs, A, E, as well as of ΨP values, which were around − 0.1 MPa. Trees irrigated only during the fruit cell division period (stage I) and the ripening period (stage III) (T3) showed a small decrease (10%) in leaf gas exchanges. A regulated deficit irrigation (RDI) applied only during the fruit cell growth (stage II) on trees and well-irrigated during the fruit cell division period and the ripening period (T4) seems to have little effects on gas exchanges and no effects on yield and fruit quality before and after storage. Therefore, the results showed that with the exception of RDI treatment, increasing water stress reduced the physiological parameters due to stomatal and non-stomatal limiting factors. However, such regulated deficit irrigation saved 45% of water compared to the comfort irrigation. Considering these results, regulated deficit subsurface drip irrigation applied during the fruit growth II is a sustainable strategy for saving water, increasing water use efficiencies, and preserving the physicochemical quality of the apple fruits before and after storage.

Determination of Basal Temperature and Its Relationship With Jatropha Crop in Irrigated and Non-irrigated System

Full plant growth and development require, among others, air temperatures and water availability at levels appropriate to each crop. The effect of temperature on plant development can be represented by the thermal sum, which requires the lower basal temperature for each plant species. However, plant responses may be different when associated with different soil water contents. This work determined the lower and upper basal temperature of Jatropha curcas L. and verified the relationship between thermal sum and crop development under different water regimes, in the climatic conditions of Goiânia, GO, Brazil. We evaluated twenty-four plants cultivated at the planting density of 2,222.2 plants ha-1. Of these, twelve plants were irrigated from October 2010 to October 2012, whereas the other twelve remained unirrigated. Basal temperatures were estimated by four different methods described in the literature, in two phases of observation, maturity and total cycle. From the results, regression analysis was performed. The lower basal temperature was 4.9 and 7.2 °C, and upper basal temperature was 38.8 and 36.8 °C, respectively, for the maturity and total cycle stages. The accumulated thermal sum for the complete plant development of jatropha was 10,314.55 DD (±1574.73) for the non-irrigated treatment, and 9,260.67 DD (±735.06) for the irrigated treatment. The results of plant development showed good coefficient of determination in relation to the accumulated thermal sum.

Effects of Vegetation-Free Strip Width and Irrigation on Newly Planted Peach

ABSTRACTField experiments were conducted at two locations (Clayton and Jackson Springs, NC) to determine the influence of vegetation-free strip width (VFSW) and irrigation on newly planted peach growth and yield in a low-density orchard with a volunteer weedy ground cover. The experiments included VFSW of 0, 0.6, 1.2, 2.4, 3, or 3.6 m under irrigated or nonirrigated conditions. Seasonal variation in the orchard floor vegetation was observed as different weed species reported in summer and winter. However, this difference was not apparent with respect to VFSF and irrigation. At Jackson Springs, NC, the predicted irrigated VFSW which would produce the same trunk cross-sectional area (TCSA) as the grower standard (3-m nonirrigated) was 1.5, 1.3, and 0.8 m for one-, two-, and three-year-old trees, respectively. The predicted irrigated VFSW which would produce the same yield as the grower standard was 1.16 m. At Clayton, TCSA and fruit yield were not different by irrigation, but did increase linearly with VFSW. At both locations, leaf nitrogen (N) concentration was lower in irrigated trees than nonirrigated trees. Leaf N, leaf area, and SPAD were positively related to VFSW at Jackson Springs. In contrast, leaf N concentration was not different by VFSW at Clayton. However, leaf area and SPAD were positively related to VFSW at Clayton. These results suggest that a 1.5 m VFSW combined with proper irrigation and fertilization will produce tree growth and yield in newly planted orchard with volunteer weedy vegetation similar to the current grower standard in the southeastern USA.

The effect of irrigation on chestnut physiology and production (Castanea sativa)

This study aims to evaluate the influence of irrigation on the chestnutRSQUOs physiology, nut calibre and yield. The study was carried out during 2015 and 2016, in a chestnut orchard of the 'Judia' cultivar, located in Braganca in the northeast of Portugal. Two irrigation systems were installed in 10 trees each: drip (TI) and micro-sprinkler (SI). Irrigation was triggered when stem water potential fell below -1.2 MPa. Ten other sample trees were kept in rainfed conditions (NI). From June to October the stem water potential, chlorophyll fluorescence, photosynthetic and transpiration rates were monitored and production per tree was weighted. The total mean amount of water furnished was of 470 and 925 m3 ha-1 in 2015 and 2016, respectively. On both years the photosynthetic and transpiration rates were higher for irrigated trees (8.6 µmol CO2 m-2 s-1 and 1.9 mmol H2O m-2 s-1) than for non-irrigated ones (7.6 µmol CO2 m-2 s-1 and 1.8 mmol H2O m-2 s-1). Chestnut production was 26% higher for irrigated trees with 48.2 kg tree-1 and nut size was smaller in non-irrigated trees (93 nuts kg-1) than for the irrigated ones (75 nuts kg-1). Despite of these differences the climatic conditions, particularly the hotter temperatures in 2016, affected production and nut size. From 2015 to 2016 production decreased 16, 27 and 33% for SI, TI and NI, respectively. Nut size also decreased 90, 45 and 24% for NI, TI and SI, respectively, when the temperature sum (May-October) varied from 2348 to 2504°D. The introduction of irrigation in the chestnut orchard is beneficial but temperature plays an important role in the tree physiology and production.

The scientific background of competitive maize production

The effect and interaction of crop production factors on maize yield has been examined for nearly 40 years at the Látókép Experiment Site of the University of Debrecen in a long-term field experiment that is unique and acknowledged in Europe. The research aim is to evaluate the effect of fertilisation, tillage, genotype, sowing, plant density, crop protection and irrigation. The analysis of the database of the examined period makes it possible to evaluate maize yield, as well as the effect of crop production factors and crop year, as well as the interaction between these factors.
 Based on the different tillage methods, it can be concluded that autumn ploughing provides the highest yield, but its effect significantly differed in irrigated and non-irrigated treatments. The periodical application of strip tillage is justified in areas with favourable soil conditions and free from compated layers (e.g. strip – strip – ploughing – loosening). Under conditions prone to drought, but especially in several consecutive years, a plant density of 70–80 thousand crops per hectare should be used in the case of favourable precipitation supply, but 60 thousand crops per hectare should not be exceeded in dry crop years. The yield increasing effect of fertilisation is significant both under non-irrigated and irrigated conditions, but it is much more moderate in the non-irrigated treatment.
 Selecting the optimum sowing date is of key importance from the aspect of maize yield, especially in dry crop years. Irrigation is not enough in itself without intensive nutrient management, since it may lead to yield decrease.
 The results of research, development and innovation, which are based on the performed long-term field experiment, contribute to the production technological methods which provide an opportunity to use sowing seeds, fertilisers and pesticides in a regionally tailored and differentiated way, adapted to the specific needs of the given plot, as well as to plan each operation and to implement precision maize production.

Growth of irrigated and fertilized pequi trees in the Cerrado of Goiás, Brazil

El objetivo de este estudio fue evaluar el crecimiento de árboles de pequi en función de la irrigación y la fertilización orgánica, en un experimento de bloques al azar con seis parcelas y cuatro repeticiones. Se utilizaron 16 plantas por parcela espaciadas 5 x 5 m. Se evaluaron cuatro tratamientos: IF = Riego con fertilización, IWF = Riego sin fertilización, WIF = Sin riego con fertilización, y WIWF = Sin riego y sin fertilización, en parcelas subdivididas. El sistema de riego utilizado fue microaspersión. El volumen de agua aplicada se estimó en función de la evapotranspiración de los árboles de pequi. Las dosis de fertilización se aplicaron en noviembre de 2014 utilizando material de compostaje y Yorim; y en noviembre de 2015 se utilizó estiércol de ganado y estiércol de pollo. Cada mes se evaluaron la altura y el perímetro del tallo; el dosel fue evaluado en un huerto de 7,1 años. La temperatura de la hoja y la transpiración fueron evaluadas por el flujo de savia en árboles irrigados y no irrigados. El pequi no respondió a los tratamientos en términos de altura y perímetro del tallo. El riego proporcionó árboles con áreas más grandes de copa. Cuando se regaron, la temperatura de las hojas de los árboles de pequi se mantuvo por debajo de las temperaturas promedio del aire, independientemente de los períodos secos o lluviosos. Sin riego, las plantas presentaron estrés hídrico durante la estación seca. Bajo condiciones de lluvia, la transpiración media del árbol de pequi fue de 24,09 L d-1 por planta. Cuando se regaba, era en promedio de 42,29 L d-1 por planta.

Irrigation positively affects the chestnut’s quality: The chemical composition, fruit size and sensory attributes

Abstract In the northeast of Portugal there is a tendency to introduce irrigation system on the chestnut orchards but the effect of irrigation on the chestnut’s quality has not been studied yet. This study aims to evaluate the effect of irrigation on the ‘Judia’ cultivar chestnuts quality concerning its chemical composition, fruit size and tastiness. Three treatments were applied during 2015 and 2016: the drip system, the micro-sprinkler system and a non-irrigated treatment. In both years the bigger chestnuts and production were always present in irrigated treatments. Significant differences among treatments were found in ashes, starch, soluble sugars, and crude protein contents in 2015, but in 2016 no significant differences were found. Moreover, the non-irrigated chestnuts were the sweetest but with smaller calibre. The chestnuts from micro-sprinkler were the firmest and they were as sweet as the drip's chestnuts. Results suggest that irrigation, namely with sprinkler system, valorise the chestnuts by increasing its size and keeping its nutritional value and its sensory quality.

Effect of adjuvant on pendimethalin and dimethenamid-P behaviour in soil

Adjuvants are used to improve pesticides’ performance. It is expected that adjuvants should increase sorption and persistence, as well as decrease mobility of pesticides in soils. Impact of the “Grounded” brand adjuvant on the behaviour of two herbicides, pendimethalin and dimethenamid-P, was investigated in a Haplic Chernozem. Both herbicides were tested in a laboratory batch sorption experiment with and without adjuvant. The sorption experiment showed that adjuvant negligibly increased dimethenamid-P sorption (KF = 2.12 and 2.15 cm3/n μg1 − 1/n g−1) but significantly increased pendimethalin sorption (KF = 270.1 and 3096.4 cm3/n μg1 − 1/n g−1). In field conditions, both herbicides were retained mainly in the topsoil layer (0–5 cm). The pendimethalin dissipation half-lives were similar for all treatments (ranging from 43.0 to 44.6 days) and were not influenced by either irrigation (p = 0.86) or adjuvant (p = 0.9). The dimethenamid-P dissipation half-lives ranged from 8.8 days for irrigated treatment without adjuvant to 12.9 days for non-irrigated treatment with adjuvant. Dimethenamid-P dissipation half-life in treatments with adjuvant was significantly longer (p = 0.049) than was half-life in a treatment without adjuvant. Significantly longer dissipation half-life was observed also in non-irrigated treatments than in irrigated treatments (p = 0.044).

Drought and irrigation affect transpiration rate and morning tree water status of a mature European beech (Fagus sylvatica L.) forest in Central Europe

AbstractSeverity and frequency of recurrent droughts is likely to be amplified by recent climate changes and may adversely affect large areas of temperate forests. This study addresses the ecophysiological responses of a mature beech forest in Central Europe (Slovakia, 450 m a.s.l.) exposed to drought during the growing seasons of 2012–2014. Sap flow and stem circumference changes of European beech (Fagus sylvatica L.) were measured in two contrasting treatments (drought vs. irrigation). Limited water availability reflected in the morning tree water status (morning stem contraction, ΔW) significantly reduced transpiration. Trees stressed by drought in the years 2012 and 2013 showed remarkably lower values of morning ΔW than those in the irrigated group. This suggests (a) lower water potential of the stem‐conducting tissues and (b) increased use of internally stored water to maintain daily transpiration. Additionally, morning ΔW showed a close relationship with soil water potential, particularly in the nonirrigated trees. Potential evapotranspiration (PET) explained less variability in the transpiration of the control stand than that of the irrigated stand. The use of a simple analysis of covariance model comprising morning ΔW and PET interaction significantly increased the explained variability in transpiration in the control stand. Morning ΔW of mature beech trees seems to be a useful and easily obtainable non‐invasive bioindicator of their ability to reduce and regulate transpiration in relation to atmospheric evaporative demands in response to drought.

Influence of irrigation treatments on the yield and quality of ‘Istrska belica’ olive oil

In recent years, Slovenian olive growers and producers have faced problems in achieving constant yields and quality of olive oil due to extreme weather conditions, especially because of the more frequent occurrence of drought. A technically accomplished pilot automatic irrigation system for olive trees was established. In 2015, the impact of different irrigation treatments (0, 15, 33, 40 and 100% ETc (crop evapotranspiration)) on olive cultivar 'Istrska belica' were studied to determine the minimum amount of added water that has a positive effect on the yield and quality of the extra virgin olive oil produced. The study results showed that the quantity of applied water equal to 100% ETc had a significant effect on yield of olive fruits. The average fruit mass of the trees grown under full irrigation (100% ETc) was significantly higher than that of those given rain-fed and deficit irrigation treatments (15, 33 and 40% ETc), with no significant differences found between these treatments. The fatty acid contents showed the highest amount of oleic acid (75.61%) at 100% ETc and the lowest amount (74.69%) at 15% ETc, while the highest amount of linoleic acid (6.52%) was determined at 15% ETc and the lowest (5.98%) at 100% ETc. Total biophenol content and biophenol composition was determined. The 40% ETc irrigation system produced the highest amounts of total biophenols, total oleuropein and total ligstroside derivatives (1076, 562 and 388 mg kg-1, respectively), while the lowest results (883, 477 and 299 mg kg-1, respectively) were determined in the control system (0% ETc). The organoleptic assessment of the olive samples showed that the positive sensory attributes of fruity, bitter and pungent were more intensive at 33% ETc and were graded highest. Olive oil from non-irrigated trees (0% ETc) received the lowest sensory score.

Shifts of irrigation in Aleppo pine under semi-arid conditions reveal uncoupled growth and carbon storage and legacy effects on wood anatomy

Climate models forecast progressive aridification in the Mediterranean region. These warmer and drier conditions will probably lead to a decrease in carbon fixation and growth rates of drought-prone forests. To improve our knowledge on how water availability drives radial growth, wood anatomy and carbon storage we compared changes during a 40-year period in tree-ring width, wood-anatomical traits (tracheid lumen area, cell-wall thickness and parenchyma area), and stem sapwood non-structural carbohydrates (NSC) concentrations. We studied the drought-tolerant Aleppo pine (Pinus halepensis) comparing trees subjected to three irrigation regimes (control trees, no irrigation; IR trees, irrigated trees; TI trees, temporarily irrigated trees). Tree-ring width of TI trees widely overtook growth rates shown by IR trees during the irrigation treatment (1980s), whereas transversal lumen area and cell-wall thickness presented similar values in both groups of trees. Non-irrigated trees showed the lowest growth rates and also formed tracheids with the smallest lumen area and the narrowest cell walls. After the irrigation period, TI and trees without irrigation showed similar year-to-year growth variability. Lumen area of TI trees took 4–5 years to show values similar to those of the non-irrigated group. The TI trees had lower ray parenchyma area percentages during the irrigation period; afterwards both TI and non-irrigated trees formed similar amounts of ray parenchyma which were always higher than in IR trees. NSC concentrations were lower for IR trees suggesting either a dilution effect due to their significantly larger biomass or a higher demand for NSC by other carbon sinks such as primary growth. Aleppo pine may coordinate carbon supply and demand (growth) under changing conditions of water availability but long-term modification in soil moisture lead to legacy effects on wood anatomy.

Phenology of African mahogany plants submitted to irrigation

In the searching of forest species with good wood quality, easy adaptability and high commercial value, the African mahogany (Khaya ivorensis Chev. A.) have been a good alternative. This study aimed evaluate the phenometric responses of African Mahogany submitted to irrigation. The field experiment was carried out in Bonfinópolis-GO, Brazil, with young plants of African mahogany, being 5 irrigated and 5 non-irrigated. The following variables were evaluated: plant height, stem heigh, number of leaves and leaflets, stem diameter and leaf area. A completely randomized design was used in a bi-factorial scheme 2x9 (A: irrigated and non-irrigated; D: 0, 120, 180, 240, 300, 360, 420, 480, 540 days after transplanting). All the variables showed significant differences not only for irrigated and non-irrigated treatments but also for the times of evaluation, except for stem diameter. Irrigation resulted in higher growth of plants and the irrigation of young African mahogany plants should be used mainly in drought period.

Irrigation and Nitrogen Regimes Promote the Use of Soil Water and Nitrate Nitrogen from Deep Soil Layers by Regulating Root Growth in Wheat.

Unreasonably high irrigation levels and excessive nitrogen (N) supplementation are common occurrences in the North China Plain that affect winter wheat production. Therefore, a 6-yr-long stationary field experiment was conducted to investigate the effects of irrigation and N regimes on root development and their relationship with soil water and N use in different soil layers. Compared to the non-irrigated treatment (W0), a single irrigation at jointing (W1) significantly increased yield by 3.6–45.6%. With increases in water (W2, a second irrigation at flowering), grain yield was significantly improved by 14.1–45.3% compared to the W1 treatments during the drier growing seasons (2010–2011, 2012–2013, and 2015–2016). However, under sufficient pre-sowing soil moisture conditions, grain yield was not increased, and water use efficiency (WUE) decreased significantly in the W2 treatments during normal precipitation seasons (2011–2012, 2013–2014, and 2014–2015). Irrigating the soil twice inhibited root growth into the deeper soil depth profiles and thus weakened the utilization of soil water and NO3-N from the deep soil layers. N applications increased yield by 19.1–64.5%, with a corresponding increase in WUE of 66.9–83.9% compared to the no-N treatment (N0). However, there was no further increase in grain yield and the WUE response when N rates exceeded 240 and 180 kg N ha−1, respectively. A N application rate of 240 kg ha−1 facilitated root growth in the deep soil layers, which was conducive to utilization of soil water and NO3-N and also in reducing the residual NO3-N. Correlation analysis indicated that the grain yield was significantly positively correlated with soil water storage (SWS) and nitrate nitrogen accumulation (SNA) prior to sowing. Therefore, N rates of 180–240 kg ha−1 with two irrigations can reduce the risk of yield loss that occurs due to reduced precipitation during the wheat growing seasons, while under better soil moisture conditions, a single irrigation at jointing was effective and more economical.

Response of winter wheat grain yield and water use efficiency to deficit irrigation in the North China Plain

Water resources in the North China Plain (NCP) are limited, so it’s in urgent need to optimize deficit by irrigation for sustainable winter wheat production in this area. Winter wheat grain yield (GY), contribution of dry matter (DM) remobilization to GY (CDMRG), and water use efficiency (WUE) were investigated in NCP. Compared with non-irrigation treatment, irrigated with 60 mm each at the winter wheat jointing stage (JS) and heading stage (HS) achieved reasonable winter wheat GY and WUE. Compared with irrigation with 120 mm only at JS and irrigation with 40 mm each at JS, HS, and milking stage (MS) of winter wheat, irrigation with 60 mm each at JS and HS provided the highest CDMRG, which resulted to the highest GY and WUE; this result was mainly due to a significant increase of the spike numbers (SN) per m2. The results suggest that in the NCP, in order to achieve reasonable GY and WUE, winter wheat should be irrigated with 60 mm each at JS and HS.

Irrigation and weed control alter soil microbiology and nutrient availability in North Carolina Sandhill peach orchards

Orchard management practices such as weed control and irrigation are primarily aimed at maximizing fruit yields and economic profits. However, the impact of these practices on soil fertility and soil microbiology is often overlooked. We conducted a two-factor experimental manipulation of weed control by herbicide and trickle irrigation in a nutrient-poor peach (Prunus persica L. cv. Contender) orchard near Jackson Springs, North Carolina. After three and eight years of treatments, an array of soil fertility parameters were examined, including soil pH, soil N, P and cation nutrients, microbial biomass and respiration, N mineralization, and presence of arbuscular mycorrhizal fungi (AMF). Three general trends emerged: 1) irrigation significantly increased soil microbial biomass and activity, 2) infection rate of mycorrhizal fungi within roots were significantly higher under irrigation than non-irrigation treatments, but no significant difference in the AMF community composition was detected among treatments, 3) weed control through herbicides reduced soil organic matter, microbial biomass and activity, and mineral nutrients, but had no significant impacts on root mycorrhizal infection and AMF communities. Weed-control treatments directly decreased availability of soil nutrients in year 8, especially soil extractable inorganic N. Weed control also appears to have altered the soil nutrients via changes in soil microbes and altered net N mineralization via changes in soil microbial biomass and activity. These results indicate that long-term weed control using herbicides reduces soil fertility through reducing organic C inputs, nutrient retention and soil microbes. Together, these findings highlight the need for alternative practices such as winter legume cover cropping that maintain and/or enhance organic inputs to sustain the soil fertility.

Seasonal changes of macro- and micro-nutrients concentration in olive leaves

ABSTRACTLeaves of olive (Olea europaea var. minor rotunda) were collected from mature non-irrigated trees in an “off” year, at monthly intervals, from May 2015 to April 2016. Leaf concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn) and boron (B) were determined. Seasonal fluctuation curves were developed for each nutrient, in order to use them for interpretation of leaf analysis. Concentrations of N, P, K, Ca and Mg showed significant fluctuation throughout the year, while B, Fe, Mn and Zn showed less intense changes. Nutrient accumulation varied according to tree vegetative growth and weather conditions.

The Effects of Irrigation Regimes on the Yield and Water Use of Eggplant (Solanum melongena L.)

The general objective of this study was to specify the influence of deficit irrigation on yield for eggplant grown under unheated greenhouse condition. The area trials were conducted at the Agricultural Research Station of Yenişehir Vocational School of Uludag University in Bursa, Turkey during growing season of 2007. In the study, irrigation regimes consisted of full irrigation (1.00 K1 cp ) and three deficit irrigation treatments (K2 cp , K3 cp , and K4 cp corresponding to 0.75, 0.50 and 0.25 of accumulative pan evaporation). A nonirrigated treatment (K5 cp ) was also designed for control purpose. Applied irrigation water amounts were changed between 85 and 464 mm, and water consumption were varied from 170 to 472 mm. Eggplant yield, length, diameter, weight and dry matter were significantly influenced by irrigation water level. The highest yield averaging 62 t ha -1 was obtained at K1 cp . Crop yield response factor (k y ) for eggplant was found as 1.14. Water use efficiency (WUE) and irrigation water use efficiency (IWUE) for the K2 cp treatment were calculated to be 13.16 and 10.63 kg m -3 . These were the highest WUE and IWUE values. K2 application (75%) can be recommended as the most effective irrigation level for the eggplant to which drip irrigation is applied under scarce water resource and unheated greenhouse conditions.

The effects of autumn foliar applications of boron and urea on flower quality, yield, boron and nitrogen reserves of apricot

ABSTRACTIn order to determine the effects of autumn foliar application of boron (B) and/or urea on abortive flower ratio, yield, fruit weight, total soluble solid (TSS) and B and nitrogen (N) contents of reserves of non-irrigated apricot trees, field experiments were carried out between 2009 and 2012 in Malatya province of Turkey. The application of B and/or urea stimulated perfect flower development, B and N accumulation and resulted in significant yield increase. Boron, urea and B+urea applications increased fruit yield by 33.1%, 26.1% and 26.9%, decreased abortive flower ratio by 34.6%, 27.1% and 35.9% compared to the control, respectively. In addition, B and N contents of wood, bark and buds of apricot trees were significantly increased by B and/or urea treatments. It was also observed that B and N contents were the highest in bud compared to wood and bark in all treatments. The highest B (16.53 ppm) and N (1.56%) contents were determined to buds in B+urea treatment. The results of this study suggest that autumn foliar B and/or urea application have the potential to decrease abortive flower ratio and increase the yield and B and N contents of reserves of apricot trees under non-irrigated conditions.

Effects of irrigation on yield and oil quality of different olive cultivars grown in semi-arid conditions of Tunisia

To understand the relations between water availability existing in semi-arid conditions of central Tunisia and yield components of olive trees, a field experiment was carried out to study the behavior of local and foreign cultivars under two irrigation regimes (small water supply 10% ETc which was closed to rain-fed condition and full irrigated 100% ETc). The trial was carried out over a 2-year period where the two different irrigation treatments were applied. Yield, fruit characteristics, oil quality indices (free fatty acid composition, acidity, UV absorption at 232 and 270 nm, total polyphenols, chlorophyll) were determined for both irrigated and non-irrigated treatments. Maximum production recorded over the two growing season (on year followed by off year), were given by 'Picholine', 'Chemlali', 'Coratina' and 'Koroneiki' irrigated with only 10% ETc which, noted a biannual yield varying between 16 kg tree-1 (3246 kg ha-1) and 34 kg tree-1 (6936 kg ha-1). Conversely, 'Chetoui' showed the lowest biannual yield which did not exceed 8 kg tree-1 (1600 kg ha-1) even for trees which received 100% ETc. The typical alternate bearing behaviour of this specie alters the producing pattern of the plant making less evident water effect. On the other hand, water supply caused an increase of the fruit weight and the pulp:stone ratio for all cultivars while it did not affect the oil chemical parameters. The results showed that 'Picholine', 'Chemlali', 'Coratina' and 'Koroneiki' showed an economical satisfactory yield and interesting oil characteristics (low palmitic acid and high oleic acid) even under semi-arid conditions.