Playing quality,growth rate,thatch accumulation and tolerance to moss and annual bluegrass invasion as influenced by irrigation strategies on red fescue putting greens

Conversion from annual bluegrass or bentgrasses to red fescue could be an efficient way to minimise water use on golf greens. Our objective was to investigate the influences of four irrigation strategies on red fescue water use efficiency, turf quality, growth rate and resistance to annual bluegrass and moss invasion. The trial was carried out from August 2013 to August 2015 on a green established according to USGA recommendations under a rainout shelter at Landvik, Norway (58 °N). On average for 2 years, irrigation to field capacity once per week (FC 1) and deficit irrigation to 60% of FC three times per week (DEF 3) reduced the water consumption by 49% and 72% relative to irrigation to FC three times per week (FC 3). Both DEF 3 and FC 1 retained acceptable turf quality and reduced annual bluegrass in the second year by about one‐third. Better control of annual bluegrass was obtained with deficit irrigation to 60% of FC once per week (DEF 1), but this treatment did not produce acceptable turf quality. Compared with FC 3, DEF 3, FC 1 and DEF 1 gave harder surfaces and reduced the moss invasion in the second year by 66%, 90% and 93%, respectively. Irrigation effects on root development and thatch organic matter after 2 years were not significant, although the thatch layer depth was 3–4 mm greater in FC 1 than in the other treatments. In conclusion, DEF 3 and FC 1 are both effective irrigation strategies for managing red fescue greens with less water use.     

Nitrogen fertilization of warm‐season turfgrasses irrigated with saline water from varying irrigation systems. 1. Quality,spring green‐up and fall colour retention

A 3‐year study was conducted at New Mexico State University in Las Cruces, NM, to investigate the effects of different fertilization treatments on turf performance when water conservation strategies are applied. These strategies include the use of non‐potable saline irrigation water and the use of efficient subsurface irrigation systems. Two low water use warm‐season grasses, “Princess 77” bermudagrass (Cynodon dactylon L.) and “Sea Spray” seashore paspalum (Paspalum vaginatum O. Swartz), were irrigated with either potable [Electrical Conductivity (EC) = 0.6 dS/m] or saline (EC = 3.1 dS/m) water from either an overhead or a subsurface drip irrigation (SDI) system. Four different fertilizers, liquid slow release, granular slow release, granular urea and liquid urea, were applied at two rates: 10 and 20 g N m^?2 year^?1 for “Sea Spray” and 20 and 30 g N m^?2 year^?1 for “Princess 77.” Spring green‐up, summer quality and fall colour retention were determined using digital image analysis, visual quality ratings and normalized difference vegetation index. Generally, subsurface drip‐irrigated grasses were slower to green‐up than overhead irrigated ones. “Sea Spray” irrigated from the SDI system took 18, 28 and 15 days longer to reach 80% green cover in 2010, 2011 and 2012, respectively, than their sprinkler‐irrigated counterparts. The combination of “Princess 77” and overhead irrigation reached 80% green cover 35 (in 2010), 34 (in 2011) and 12 (in 2012) days faster than SDI‐irrigated “Princess 77.” Fertilization rate and type had no effect on summer turfgrass quality of “Princess 77” irrigated from a sprinkler system throughout the research period reaching ratings of greater than 7 during all 3 years. Similar results were observed for “Princess 77” irrigated from a SDI system during 2010 and 2011. Summer quality of sprinkler‐irrigated “Sea Spray” was negatively affected by liquid fertilization. During two of three summers, visual quality of plots fertilized with either liquid slow release or liquid urea was lower than “Sea Spray” fertilized with granular fertilizer. Further research is needed to investigate the effect of fertilization on bermudagrass and seashore paspalum over a wider nitrogen range including both granular and foliar products.     

柳园口灌区参考作物腾发量的长期变化趋势 及其对灌溉需水量的影响

研究该文的目的在于揭示了柳园口灌区参考作物腾发量的长期变化规律,阐明其产生原因及可能产生的影响,为应对气候变化对农业生产带来的负面影响提供基础。采用FAO-56推荐的Penman-Monteith公式计算河南省柳园口灌区1983—2003年的逐日参考作物腾发量,用Mann-Kendall检验对灌区的参考作物发量进行长期变化趋势分析,对参考作物腾发量的长期变化趋势及其与气象因素、灌溉引水量的关系进行了分析。结果表明,在过去的20多年中,ET₀呈极显著的下降趋势,其下降的幅度约为50mm/10年;导致ET₀下降的主要原因是日照时数下降,其次是风速的下降,气温升高并不足以抵消日照时数和风速的下降而使ET₀上升;ET₀的下降主要出现在4月和6—8月。在降雨量变化不明显的情况下,灌溉季节的ET₀的下降使灌区的灌溉需水量呈下降趋势,而灌区近年来的引黄水量减少也证明了这一事实。因此,除了节水灌溉技术的推广,气候变化使灌溉需水量减少,灌区的节水也有气候变化的“贡献”。     

Nitrogen fertilization of warm‐season turfgrasses irrigated from varying irrigation systems: 2. Carbohydrate and protein content

A 3‐year study was conducted at New Mexico State University in Las Cruces, NM, to investigate whether different fertilization treatments affect the carbohydrate and protein content in two warm‐season grasses grown using water conservation strategies such as non‐potable saline irrigation water and a subsurface irrigation system. “Princess 77” bermudagrass (Cynodon dactylon L.) and “Sea Spray” seashore paspalum (Paspalum vaginatum O. Swartz) were irrigated with either potable (electrical conductivity [EC] = 0.6 dS m^?1) or saline (EC = 3.1 dS m^?1) water from either an overhead or a subsurface drip irrigation system. Four different fertilizers were used in this study: liquid slow release, granular slow release, granular urea and urea liquid, at two rates: 10 and 20 g N m^?2 yr^?1 for “Sea Spray” and 20 and 30 g N m^?2 yr^?1 for “Princess 77.” Carbohydrate (sucrose, starch, total soluble carbohydrates and total non‐structural carbohydrates) and protein content of the grasses were measured, and their effect on spring green‐up was determined. The total carbohydrate content within the stolons and rhizomes was found to be closely associated with speed of spring green‐up, resulting in R² values ranging from 0.36 to 0.76. The relationship between green‐up and carbohydrate content was similar for both grasses. Fertilizer treatment did not affect carbohydrate content in either grass under either irrigation system. Further analysis revealed that carbohydrate content in February was the best determinant for spring green‐up. Other sampling months also showed a significant correlation with spring green‐up, but with lower R² values.     

灌溉制度对机采棉生长、产量及品质的影 响简

 1膜2管6行是新疆机采棉的主要种植模式。为确定该模式适宜的灌溉制度,采用田间试验研究了灌溉频率（F5、F8）与灌水定额（I80、I60和I40）对棉花生长、产量、品质及水分利用效率的影响。结果表明,高频高定额（F5I80）与高频中定额（F5I60）灌溉可有效降低棉花株高,增加叶面积指数,提高蕾铃生物量在地上部中的比例。灌溉频率相同时,灌水量过高与过低均不利于棉花增产;灌水定额相同时,高频（F5）较低频（F8）灌溉增产0.59%~1.56%。灌溉制度对棉花纤维品质无显著影响。灌水定额显著影响棉花耗水量及水分利用效率,而灌溉频率对二者影响不显著。研究认为高频（F5）和中灌溉定额（I60）是南疆地区机采棉种植模式适宜的灌溉制度,即在全生育期内灌水12次,灌溉定额300 mm左右。     

Fertility and growth in the field of Lolium perenne and Festuca rubra plants regenerated from suspension cultured cells and protoplasts

The effect of regeneration of Lolium perenne and Festuca rubra from embryogenic suspension cells and protoplasts on fertility and growth was evaluated. Embryogenic suspension cultures were either routinely subcultured or cryopreserved and re-established. Phenology, morphology and fertility of regenerated plants were studied for two growing seasons in a replicated field experiment. Most regenerated L. perenne and F. rubra plants showed a delay in inflorescence emergence, a reduced seed yield and differences in morphological traits when compared with seed-grown plants. For L. perenne, performance of plants regenerated from cryopreserved suspension cultures and protoplasts was similar to that of respective plants regenerated from routinely maintained suspension cultures. However, differences in performance were observed for respective regenerants in F. rubra. The phenotypic deviation observed was partly reflected in the randomly amplified polymorphic DNA (RAPD) analysis performed. However, regenerants of both species showing similar, or even superior performance to the seed-grown plants were also found. Embryogenic suspension cells and corresponding protoplasts of L. perenne and F. rubra have the potential for producing fertile, well-performing plants which can be integrated in breeding programs.     

Determining Crop and Pan Coefficients for Sugar Beet and Potato Crops under Cool Season Semiarid Climatic Conditions

This study was conducted in a region with semiarid cool climatic conditions during the period from May to October in the years 2003 and 2004, respectively. Actual evapotranspiration (ET_c) of sugar beet and potato crops was calculated according to the water balance approach. Reference evapotranspiration (ET_o) was calculated with FAO Penman–Monteith equation. Evaporation (E_pan) was measured by using class A pan. Seasonal mean ET_c was determined as 492.9 mm for sugar beet and 445.2 mm for potato. Seasonal mean pan coefficient (k_p = ET_o/E_pan) was determined as 0.74, and the seasonal mean crop coefficient (k_c = ET_c/ET_o) was determined as 0.65 for sugar beet 0.60 for potato.     

西南地区1960—2013年参考作物蒸散量时空变化特征及成因分析

基于西南地区108个气象站点1960—2013年逐日气温、降水、风速、日照时数、太阳总辐射和相对湿度数据,应用Penman-Monteith模型和ArcGIS反距离加权插值法,分析其参考作物蒸散量时空变化及影响因素。结果表明：近54年来,西南地区参考作物蒸散量在波动中呈降低趋势,其变化倾向率为 -4.509 mm/10 a,其中降低幅度以20世纪90年代最大,距平值为-19.526 mm,增幅却以70年代最显著,为12.744 mm,特别是在20世纪70年代至21世纪初,参考作物蒸散量大幅下降,最低值出现在2000年,为628.264 mm;从季节变化看,春夏季呈降低、秋冬季却有上升的趋势。参考作物蒸散量存在明显的空间差异,表现为：以云贵高原西部为高值中心,向四周递减,且低值区分布面积远大于高值区,高值区位于云南高原和广西丘陵部分地区,低值区分布在四川盆地、贵州高原、松潘高原和滇西北高海拔地区。影响西南地区参考作物蒸散量的因子主要以日照时数、风速和相对湿度为主,但各区所受主控因子却不尽相同。     

Nitrogen requirements for deficit-irrigated bermudagrass (Cynodon spp.) fairways in South Florida

Several new bermudagrass cultivars are available and commonly used on golf course fairways. However, little is known about their cultural requirements or how these cultivars perform under lower inputs regimes. A 2-year study was conducted at University of Florida, Fort Lauderdale Research and Education Center, to assess performance of four hybrid bermudagrass [Cynodon dactylon L. Pers. X Cynodon transvaalensis (Burtt-Davy)] cultivars (‘Latitude 36’, ‘Tifway 419’, ‘TifGrand’ and ‘TifTuf’), and 2 common bermudagrass (Cynodon dactylon L. Pers.) cultivars (‘Bimini’ and ‘Celebration’) irrigated at either 50% or 80% reference evapotranspiration (ET_o) and fertilised at either 0, 146, 244, or 342 kg N ha⁻¹ year⁻¹. Plots were evaluated monthly for turfgrass quality, dark green colour index (DGCI), normalised difference vegetation index (NDVI), and Chlorophyll Index, and seasonally for N tissue content. Plots watered at 80% ET_o enhanced bermudagrass quality compared to 50% ET_o, DGCI and NDVI only in two months out of 24. Latitude 36 and Celebration were the top-rated cultivars, and their quality was not affected by no N fertilisation. Conversely, TifGrand, TifTuf and Tifway that received no N fertilisation resulted in insufficient quality during the second year of the study. Insufficient quality may be linked to reduced N metabolization compared to the highest rated cultivars. Results show that new cultivars such as Latitude 36 and Bimini could be maintained at sufficient quality levels with reduced water and N inputs in South Florida.     

Effects of corn deficit irrigation and soil properties on water use efficiency. A 25-year analysis of a Mediterranean environment using the STICS model

This study analyses the role of variability induced by climate and soil properties (texture and total available soil water in the root zone, TAW) on the “corn deficit irrigation–water use efficiency” relation over a 25-year period, between 1981 and 2005, in three different sites located in the South of Italy. The analysis of water use efficiency was carried out by means of three indexes: crops water use efficiency (WUE_ET and WUE_T) and irrigation water use efficiency (IWUE). These indexes can be obtained by calculating the ratio between the yield and the seasonal values of evapotranspiration (ET), transpiration (T) and irrigation volume (I). After its validation, the STICS model was retained to simulate the variables required to determine these indexes.Climatic variability affected the three indexes in different ways during the 25-year period studied. The dispersion around the mean values of the water use efficiency is 17% on average for the WUE (ET or T) indexes, whereas it could reach 54% for the IWUE index. This last index is only poorly reliable due to the high variability of rainfall during the corn growing season in the Mediterranean region.For the same level of soil water deficit, TAW led to an improvement (the case of the site with a high TAW and loam–clay soil texture), a stabilisation (the case of the site with a high TAW and clay soil texture) or a decrease (the case of the site with a poor TAW and clay soil texture) in WUE_ET and WUE_T values. For the same conditions of soil water deficit and TAW, crops water use efficiency was higher in loam textured soil than in clay soil.The results derived by analyzing three indexes (WUE_ET, WUE_T and IWUE) converge to the same conclusions on the “corn deficit irrigation–water use efficiency” relation observed at the three different sites.The hypotheses which may explain the differences observed in the different sites studied in terms of water use efficiency are discussed, with the presentation of some suggestions devised for corn irrigation practices.     

Electron Transport Through Photosystem II Is Not Limited By A Wide Range of Water Deficit Conditions In Field‐Grown Gossypium hirsutum

Despite exhaustive literature describing drought stress effects on photosynthesis in Gossypium hirsutum, the sensitivity of photosynthetic electron flow to water deficit is heavily debated. To address this, G. hirsutum plants were grown at a field site near Camilla, GA under contrasting irrigation regimes, and pre‐dawn water potential (Ψ_PD), stomatal conductance (g_s), net photosynthesis (P_N), actual quantum yield of photosystem II (Φ_PSII) and electron transport rate (ETR) were measured at multiple times during the 2012 growing season. Ψ_PD values ranged from ?0.3 to ?1.1 MPa. Stomatal conductance exhibited a strong (r² = 0.697), sigmoidal response to Ψ_PD, where g_s was ≤0.1 mol m^?2 s^?1 at Ψ_PD values ≤ ?0.86 MPa. Neither Φ_PSII (r² = 0.015) nor ETR (r² = 0.010) was affected by Ψ_PD, despite exceptionally low Ψ_PD values (?1.1 MPa) causing a 71.7 % decline in P_N relative to values predicted for well‐watered G. hirsutum leaves at Ψ_PD = ?0.3 MPa. Further, P_N was strongly influenced by g_s, whereas ETR and Φ_PSII were not. We conclude that photosynthetic electron flow through photosystem II is insensitive to water deficit in field‐grown G. hirsutum.     

Response of Mung Bean (Vigna radiata (L.) R. Wilczek) to an Increasing Natural Temperature Gradient under Different Crop Management Systems

Increasing temperatures pose a significant threat to crop production in the tropics. A field experiment was conducted with mung bean at three locations in Sri Lanka representing an increasing temperature gradient (24.4–30.1 °C) during two consecutive seasons to (i) determine the response of mung bean to increasing temperature and (ii) test a selected set of crop management practices aimed at decreasing essential inputs such as water, synthetic pesticides and inorganic nitrogen fertilizer. The control treatment (T₁) consisted of standard crop management including irrigation, chemical crop protection and inorganic fertilizer application. Adaptation system 1 (T₂) included mulching with rice straw at 8 t ha^?1 with 30 % less irrigation and crop protection and nutrient management as in T₁. Adaptation system 2 (T₃) included crop protection using a pretested integrated pest management package with water and nutrient management as in T₂. In adaptation system 3 (T₄), 25 % of the crop's nitrogen requirement was given as organic manure (compost) at 0.8 t ha^?1 while 75 % was given as inorganic fertilizer with water management and crop protection as in T₃. Durations of both pre‐ and post‐flowering phases were reduced with increasing temperature. In the warmer (25.4–30.1 °C) yala season, seed yield (Y) of T₁ decreased with increasing temperature at 366 kg ha^?1 °C^?1. However, in maha season, Y did not show a significant relationship across the narrower temperature gradient from 24.4 to 25.8 °C. Pooling the data from both seasons showed a second‐order polynomial response with an optimum temperature of 26.5 °C. In addition to shortened durations, reduced crop growth rates and reduced pod numbers per plant were responsible for yield reductions at higher temperatures. In yala, yields of all adaptation systems at all locations were on par with yields of the respective controls. Furthermore, yala yields of T₂ and T₃ were less sensitive than T₁ to increasing temperatures (265 and 288 kg ha^?1 °C^?1). In maha, T₃ and T₄ had greater yields than the control at the relatively cooler site while having lower yields than the control at the warmer site. Maha yields of T₂ were on par with the control at both temperature regimes. While demonstrating the significant temperature sensitivity of mung bean yields, results of the present work showed that components of the tested adaptation systems could be promoted among smallholder farmers in Asia, especially in view of their long‐term environmental benefits and contributions to sustainable agriculture in a warmer and drier future climate.     

Growth and Ionic Content of Quinoa Under Saline Irrigation

Drought and salinity are the most important abiotic stresses that affect plant's growth and productivity. The aim of the present work was to evaluate the effect of salt and water deficit on water relations, growth parameters and capacity to accumulate inorganic solutes in quinoa plants. An irrigation experiment was carried out in 2009 and 2010 in the Volturno river plain. Three treatments irrigated with fresh water (Q100, Q50 and Q25) and three irrigated with saline water (Q100S, Q50S and Q25S) were tested. For saline irrigation, water with an electrical conductivity of 22 dS m^?1 was used. Actual evapotranspiration (ET_a), water productivity (WP), biomass allocation, relative growth rate (RGR), net assimilation rate (NAR), specific leaf area, leaf area ratio and ions accumulation of quinoa plants were evaluated. WP and plant growth were not influenced by saline irrigation, as quinoa plants incorporated salt ions in the tissues (stems, roots, leaves) preserving seed quality. Treatment with a reduction in the irrigation water to 25 % of full irrigated treatment (Q25) caused an increase in WP and a reduced dry matter accumulation in the leaves. Quinoa plants (Q25) were initially negatively affected by severe drought with RGR and NAR reduction, and then, they adapted to it. Quinoa could be considered a drought tolerant crop that adapt photosynthetic rate to compensate for a reduced growth.     

Increasing biodiversity of irrigated rice in Africa by interspecific crossing of Oryza glaberrima (Steud.) × O. sativa indica (L.)

The African rice Oryza glaberrima, traditionally cultivated since more than 3.500 years, is of poor agronomic performance but resistant/tolerant to various stresses and diseases. The introduction of these characters into O. sativa cultivars is difficult since crossing barriers cause spikelet sterility in F1. Backcrossing can restore fertility and recently facilitated the development of fertile O. glaberrima × O. sativa ssp. japonica hybrid progenies for rain fed systems. With the objective to gain access to African rice germplasm for improvement of irrigated rice, crosses were performed with eighteen O. glaberrima and twenty O. sativa ssp. indica accessions. In total about one hundred F1-hybrid grains were obtained. The F1 plants were all completely sterile and backcrossing (BC) to O. sativa was performed in order to restore spikelet fertility. Monitoring of Tog5681 × IR64 hybrid progenies under field conditions revealed a broad genetic diversity within the BC₁ and BC₂ populations. Some BC₁ and BC₂ progeny plants outperformed the O. sativa parent, indicating that the heterozygocity level and complementary gene action after two backcrosses are still sufficient to positively influence plant vigor. Spikelet fertility of progenies was highly variable, but almost complete fertility was already observed within the BC₁F₂ population. High spikelet fertility was preserved in one out of two analyzed BC₁F₃ families and inmost of the BC₂F₃ families. The ability to restore spikelet fertility within few generations and the potential of the genetic diversity present in interspecific progenies facilitates the development of plant types specifically designed for the African irrigated and lowland environment. This revised version was published online in August 2006 with corrections to the Cover Date.     

Widening the gene pool of cultivated lentils through introgression of alien chromatin from wild Lens subspecies

Wild Lens species/subspecies are a potential source for increasing genetic diversity in cultivated lentil. Four intraspecific crosses were attempted between cultivated and wild lentils. Viable hybrids were produced between L. culinaris ssp. culinaris × L. culinaris ssp. orientalis and L. culinaris ssp. culinaris × L. culinaris ssp. odomensis. Normal meiosis and pollen fertility were observed in the first set of crosses, whereas chromosomal abnormalities and reduced pollen fertility were observed in the second set of crosses. These crosses were also studied for some quantitative traits. The range, mean and coefficient of variation were calculated in parents, F₁, F₂ and BC₁ generations to determine the extent of variability generated in the cultivated lentil through introgression of genes from wild lentil. The cultivated lentil × L. culinaris ssp. orientalis crosses showed substantially higher variability for all the traits than crosses involving cultivated lentil ×L. culinaris ssp. odomensis. The results of the present study indicated that these wild subspecies can be exploited for breeding purposes and their variation can easily be utilized to widen the genetic base of the cultivated lentil.     

Haploid Production from Barley Yellow Dwarf Virus Resistant Clones of Lolium

The investigation was earned out to obtain double haploid homozygous lines of Lolium. Lolium multiflorurm ssp. gaudini cv. ‘Liwelo’, 44 clones and five different cultivars (cv.) of L. perenne were tested with regard to their anther culture response on a solid medium. Callus production and plant regeneration of the different genotypes were investigated. Within L. m. ssp. gaudini green plants have been obtained. In L. perenne significant genotypical differences in the in vitro reaction could be demonstrated. A high-responding genotype was selected which produced a maximum of 20 % green plants. A variety × temperature interaction was found for the L. perenne varieties ‘Premier’ and ‘Barlenna’. The production of 34 green plants out ot eight clones enables a first analysis to be made of the inheritance of Barley Yellow Dwarf Virus resistance in L. perenne.     

Breeding apomictic bahiagrass (Paspalum notatum Flügge) with improved turf traits

The development of a turf‐type bahiagrass could have a remarkable impact on the billion‐dollar turf industry in the south‐eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included mutants, wild types, hybrids and standard cultivars evaluated at two locations for two years. Morphological variation was observed and clonal repeatability (H²) ranged from 0.27 to 0.90. Flowering was extremely reduced in some mutants, which also exhibited dark green colour, finer texture and reduced canopy height. Cytoembryological observations revealed that diploids reproduced sexually and tetraploids by obligate or facultative apomixis. Genotypes with superior seed fertility were identified, while others were comparable to the standard cultivars. While mutant plants exhibited great morphological variation, the random mutations did not affect their reproductive mode, validating the use of mutagenesis in apomictic species. The high H² indicated that selection for improved turf attributes could be successfully performed with the advantage of clonal seed propagation.     

Pollen and pistil morphology, in vitro pollen grain germination and crossing success of Lens cultivars and species

Morphological and in vitro germination characteristics of pollen altogether with pistil and style length were analysed, so as to carry out a morphological comparison between different lentil (Lens culinaris Medik.) cultivars and wild species, as well as to correlate the morphological and functional statistics with data regarding crossing success. Pollen length and width in the different genotypes were found to have a positive and highly significant correlation with pistil and style length and in vitro pollen tube length. A cluster analysis detected two different plant groups, namely, (i) large‐seeded L. culinaris (macrosperma), and (ii) a second group formed by two subgroups, a first subgroup with L. ervoides standing alone and a second subgroup including small‐seeded L. culinaris (microsperma) and the wild L. culinaris ssp. orientalis, L. odemensis, L. nigricans. A high and significant correlation was detected between crossing success and phenotypic similarity (r > 0.98; P < 0.05), therefore implying that phenotypic similarity, based on pollen morphology and in vitro pollen length together with pistil and style length, is a good predictor of hybridization success.     

Effect of Salinity on Growth Parameters,Soil Water Potential and Ion Composition in Cucumis melo cv. Huanghemi in North‐Western China

A field trial conducted on the melon cultivar Huanghemi irrigated with saline water was carried out in Minqin County in the 2‐year period, 2007 and 2008. In three irrigation treatments, different saline water concentrations were applied, that is 0.8 g l^?1 (Control C), 2 g l^?1 (Treatment S₁) and 5 g l^?1 (Treatment S₂), reproducing the natural groundwater concentration in the county. The electrical conductivity of the saline water was as follows: 1.00, 2.66 and 7.03 dS m^?1, respectively. The aims of the study were (i) to monitor water consumption and water potential, (ii) assess, during the whole crop cycle, some growth parameters and their relations for estimating the morpho‐functional plant response irrigated with saline water and (iii) determine the ion concentration in different plant tissues to evaluate which mechanism the plant activates in the presence of high salt concentrations. Under salinity stress, the plants sustained the concentration of Ca, Mg and K, but at a level not sufficient to limit the Na adsorption. Therefore, the melon yield decreased and it was determined by a displacement of the ratio K/Na and by a lower (total potential MPa). Consequently with increasing salinity, a significant reduction was observed in: water consumption (ET c, mm), leaf area duration (LAD, m² d), on shoot dry weight aboveground (W , g plant^?1), on specific leaf area (SLA, cm² g^?1) and on leaf area ratio (LAR, cm² g^?1). In treatment S₂, in addition to these changes which mainly affected the plant morphology with effects on the biomass produced, a moderate reduction was also observed in net assimilation rate (NAR, g m^?2 d^?1), water use efficiency (WUE), a significant reduction in the energy conversion efficiency (ECE, %) and, in short, in a reduction in the relative growth rate (RGR, g g^?1 d^?1).     

Vorfruchtwirkurigen unterschiedlicher Rotationsbrachen auf Winterweizen

Effects of rotational fallows (‘set-aside land’) on subsequent winter wheat. The aim of the present study was to investigate the effects of different fallow treatment on subsequent winter wheat. The field trials included rotational fallows planted with Trifolium repens, Festuca rubra and Lolium perenne sown under winter barley compared to complete fallow and natural fallow without seed application and fallows planted with Trifolium pratense, Festuca rubra and Dactylis glomerata sown under winter wheat. After ploughing up the fallow vegetation, winter wheat was planted for 2 succeeding years at two levels of N-fertilization. Herbicides and fungicides were not applied. The following criteria were investigated: biomass-production, N-uptake, yield, weed infestation, nitrate and water content of the soil. In autumn, after ploughing up the fallow vegetation, the nitrate content of the soil (0—150 cm) increased by up to 210 kg NO₃-N/ha after complete fallow, by up to 60 kg NO₃-N/ha after natural fallow and by up to 75 and 130 kg NO₃-N/ha after fallows cropped with Trifolium repens and Trifolium pratense, respectively. Low nitrate levels of 20—27 kg NO₃-N/ha were observed after fallows planted with grass. N-immobilization caused by ploughing up grass fallows continued until the first harvest of the subsequent winter wheat. In the second year of winter-wheat, no differences of N-mineralization dependent on the previous fallow crop occurred, except in the case complete fallow which showed lower N-mineralization. It can be concluded that fallows cropped with grass lead to a higher nitrogen fertilizer requirement m the succeeding crops. Festuca rubra was able to form dense swards in strong competition with weeds and to decrease the abundance of Alopecurus myosuroides and Apera spíca-venti in subsequent winter wheat, while natural fallow and fallow planted with Trifolium repens and Lolium perenne caused epidemical increases in grass-weed density. Preceding crop effects on grain yield of the winter wheat showed a close relation to N-supply and were compensated by mineral N-fertilization. After natural fallow and fallow covered with Trifolinm repens, yield reductions due to grass-weed competition occurred. Undersown Festuca rubra seems to possess a special suitabihty for cultivation in routional fallows. It establishes itself strongly under different cover crops and is able to form dense swards in strong competition with weeds. Grass-weed density in the succeeding crops will be reduced and nitrate leaching will still be prevented after ploughing up the fallow vegetation. N-fertilization of the subsequent crops must be carried out under considerations of higher N-requirements which is probably not entirely due to a stronger N-immobilization.