RESPONSE OF LISIANTHUS TO IRRIGATION WITH SALINE WATER: ION RELATIONS

Eustoma grandiflorum (Raf.) Shinn. (lisianthus) is a moderately salt tolerant species that can be produced commercially under irrigation with saline wastewaters prevalent in two salt-affected areas of California. The objective of the present studies was to determine the effect of irrigation with saline waters of two different compositions on the ion accumulation and ion relations of lisianthus ‘Pure White’ and ‘Echo Blue’. The ionic composition of irrigation waters simulated the compositions typical of i) seawater dilutions (SWD) and ii) concentrations of Colorado River water (CCRW). Electrical conductivities (EC) of SWD and CCRW were between 2 and 12 dS · m^?1. Plants irrigated with CCRW were higher in Ca²⁺ compared to plants irrigated with SWD water. Calcium was also higher in ‘Pure White’ than in ‘Echo Blue’. Increasing EC of irrigation water caused a significant decrease in shoot and leaf Ca²⁺ concentration in ‘Echo Blue’, but had no effect on Ca²⁺ content of ‘Pure White’ shoots and leaves. Magnesium concentration in ‘Echo Blue’ was higher than in ‘Pure White’. Electrical conductivity did not significantly affect Mg²⁺ concentration of either cultivar, despite the increasingly higher external concentration. Potassium concentration of young and mature leaves of ‘Echo Blue’ increased as EC increased from 2 to 8 dS · m^?1, then decreased significantly once EC exceeded 8 dS · m^?1. Potassium concentration of ‘Pure White’ leaves decreased over the range of salinity treatments tested, suggesting that the reduced potassium ion (K⁺) activity at EC levels of 8 dS · m^?1, or less, that resulted in lower leaf?K⁺ in ‘Pure White’ did not cause a decrease in K⁺ uptake in ‘Echo Blue’. Increases in external Na⁺ caused a significant increase in Na⁺ in ‘Pure White’ leaves and these plants exhibited the best growth even when levels of Na⁺ were high enough to be considered detrimental for growth.     

RESPONSE OF NON-NODULATING,NODULATING, AND SUPER-NODULATING SOYBEAN GENOTYPES TO POTASSIUM FERTILIZER UNDER WATER STRESS

Soil moisture is a principal environmental factor limiting legume productivity in the tropics and sub-tropics. A pot experiment was conducted at the wire house of National Research Centre, Cairo, Egypt to study how potassium (K) fertilizer can mitigate the adverse effect of water stress. Three Japanese soybean (Glycine max L.) genotypes, non-nodulating (NN) (En 1282), nodulating (N) (Eneri) and super-nodulating (SN) (En-b0-1) were grown under two potassium fertilizer levels (25 and 150 mg kg^?1 soil as K1 and K2, respectively). The water stress (WS) was conducted for eight days. WS significantly reduced nodules numbers and weights, shoot dry weight, relative water content, seed yield, oil, total carbohydrate contents while protein was significantly increased in the three soybean genotypes compared with well-watered (WW). Water stress and/or K treatments caused significant increase in both free amino acids and proline as well as shoot nitrogen in the three soybean genotypes.     

TREATED EFFLUENT AND SALINE WATER IRRIGATION INFLUENCES SOIL PROPERTIES,YIELD, WATER PRODUCTIVITY AND SODIUM CONTENT OF SNOW PEAS AND CELERY

To determine the effects of irrigation water quality, plants were irrigated with normal potable water [0.25 dS m^?1 electrical conductivity (EC), 25 mg L^?1 sodium (Na), 55 mg L^?1 chloride (Cl)], treated effluent (0.94 dS m^?1 EC, 122 mg L^?1 Na, 143 mg L^?1 Cl) and saline water with low salinity (1.24 dS m^?1 EC, 144 mg L^?1 Na and 358 mg L^?1 Cl) and high salinity (2.19 dS m^?1 EC, 264 mg L ^?1Na and 662 mg L^?1 Cl) for snow peas, and high salinity (3.07 dS m^?1 EC, 383 mg L^?1 Na and 965 mg L^?1 Cl) and very high salinity (5.83 dS m^?1 EC, 741 mg L^?1 Na and 1876 mg L^?1 Cl) for celery. The greater salts build up in the soil and ion toxicity (Cl and Na) with saline water irrigation contributed to significantly greater reduction in root and shoot biomass, water use, yield and water productivity (yield kg kL^?1 of water used) of snow peas and celery compared with treated effluent and potable water irrigation. There was 8%, 56% and 74% reduction in celery yield respectively with treated effluent, high salinity and very high salinity saline water irrigation compared with potable water irrigation. The Na concentration in snow peas shoots increased by 54%, 234% and 501% with treated effluent, low and high salinity saline water irrigation. Similarly, the increases in Na concentration in celery shoots were 19%, 35% and 82%. The treated effluent irrigation also resulted in a significant increase in soil EC, nitrogen (N) and phosphorus (P) content compared with potable water irrigation. The heavy metals besides salts build up appears to have contributed to yield reductions with treated effluent irrigation. The study reveals strong implications for the use of saline water and treated effluent for irrigation of snow peas and celery. The salt build up within the root zone and soil environment would be critical in the long-run with the use of saline water and treated effluent for irrigation of crops. To minimize the salinity level in rhizosphere, an alternate irrigation of potable water with treated effluent or low salinity level water may be better option.     

EXPOSURE TO ENVIRONMENTALLY RELEVANT LEVELS OF CADMIUM PRIMARILY IMPACTS TRANSPIRATION IN FIELD-GROWN SOYBEAN

Cadmium (Cd) is a toxic heavy metal released into agricultural settings primarily due to human activities. Cadmium is readily taken up by plants from the soil and has been shown to result in numerous changes to plant growth and physiology. In this study we examined the physiological effect of environmentally relevant levels of cadmium on field-grown soybean (Glycine max). No significant differences in carbon dioxide (CO₂) assimilation response to leaf internal CO₂ concentration, chlorophyll fluorescence, or growth parameters were observed. However, we did observe an increase in sap flow, a real-time measure of transpiration. Consistent with increased sap flow there was a significant increase in total daily sap flow and peak sap flow between the control and cadmium-treated plants. Our results suggest that treatment with environmentally relevant levels of cadmium primarily impacts transpiration.     

RESPONSES OF LABLAB PURPUREUS (L.) SWEET / RHIZOBIUM SYMBIOSIS AND GROWTH TO POTASSIUM SUPPLY UNDER DIFFERENT WATER REGIMES

A pot experiment was executed in sandy clay loam soil collected from Toshka region in south of Egypt to investigate the role of potassium (K) fertilization on nodulation, dinitrogen (N₂) fixation, protein, and leghaemogloin contents of nodule cytosol and growth in water-stressed Lablab purpureus (L.) Sweet Kashrangeeg. The obtained results indicate that an adequate supply of K can help to maintain efficient Lablab purpureus/Rhizboium symbioses despite a severe water deficiency.     

NUTRIENT ACCUMULATION AND PHOTOSYNTHESIS IN GLYPHOSATE-RESISTANT SOYBEANS IS REDUCED UNDER GLYPHOSATE USE

Global production of glyphosate-resistant (GR) soybean [Glycine max (L.) Merr.] continues to increase annually; however, there are no particular specific fertilizer recommendations for the transgenic varieties used in this system largely because reports of glyphosate effects on mineral nutrition of GR soybeans are lacking. Several metabolites or degradation products of glyphosate have been identified or postulated to cause undesirable effects on GR soybeans. In this work we used increasing glyphosate rates in different application on cv. ‘BRS 242 GR’ in order to evaluate photosynthetic parameters, macro- and micronutrient uptake and accumulation and shoot and root dry biomass production. Increasing glyphosate rates revealed a significant decrease in photosynthesis, macro and micronutrients accumulation in leaf tissues and also decreases in nutrient uptake. The reduced biomass in GR soybeans represents additive effects from the decreased photosynthetic parameters as well as lower availability of nutrients in tissues of the glyphosate treated plants.     

改良剂对玉米和大豆间作植株锌铬积累的影响

通过盆栽试验,研究改良剂石灰和过磷酸钙对玉米、大豆间作植株各器官锌铬积累的影响。结果表明,不同改良剂处理后,能显著降低土壤中锌、铬有效态含量,植株各器官锌含量为:对照>低浓度石灰>高浓度石灰;铬含量为:对照>高浓度过磷酸钙>低浓度过磷酸钙,单作>间作。在间作下施用低浓度过磷酸钙改良效果最优,其中玉米根、茎、叶的锌、铬含量分别比只施用低浓度过磷酸钙单作降低30.72%、35.96%和29.51%,69.98%、64.21%和51.56%;比不施加改良剂的对照间作玉米降低55.57%、59.68%和66.57%,64.10%、76.79%和80.75%;大豆根、茎、叶的锌、铬含量分别比其只施用低浓度过磷酸钙单作降低0.26%、4.91%和16.42%,14.25%、8.16%和23.33%,比不施加改良剂的对照间作降低63.95%、69.54%和65.49%,54.15%、57.14%和57.14%。间作条件下,低浓度过磷酸钙处理在不增加大豆对锌铬吸收的前提下,大幅降低玉米对重金属的吸收,显著增加玉米产量。     

MAPPING OF IRON AND ZINC QUANTITATIVE TRAIT LOCI IN SOYBEAN FOR ASSOCIATION TO IRON DEFICIENCY CHLOROSIS RESISTANCE

Iron deficiency chlorosis (IDC) in soybean results in yield losses or in extreme cases death. Breeding for resistance has shown limited success with no cultivar having complete resistance. Mineral content of the soybean could be an indicator of the ability of the plant to withstand the effects of IDC. Iron (Fe) and zinc (Zn) concentration was examined in soybean seed and leaves. SSR, RFLP, and BARCSOYSSR markers were used to construct a linkage map used for mapping of Fe and Zn concentrations. The QTL analysis for the combined data identified one major QTL for seed Fe accumulation on chromosome 20 that explained 21.5% of the variation. This QTL was in the marker interval pa_515-1-Satt239, with marker pa_515-1 previously being used to map an Fe-efficiency QTL. This provides the first evidence of a potential genetic link between Fe-efficiency and Fe accumulation in the soybean seed.     

RESPONSE OF SOYBEAN TO SOIL APPLIED SULFUR AND BORON IN A CALCAREOUS SOIL

A greenhouse experiment with soybean grown on sulfur (S) and boron (B) deficient calcareous soil was conducted for two years in northwest India to study the influence of increasing sulfur and boron levels on yield and its attributing characters at different growth stages (55 days, maturity). The treatments included four levels each of soil applied sulfur viz. 0, 6.5, 13.4, 20.1 mg S kg^?1 and boron viz. 0, 0.22, 0.44, 0.88 mg B kg^?1 at the time of sowing. The highest dry matter yield at 55 days after sowing, DAS (19.3 g pot^?1) and maturity (straw yield ?25.2 g pot^?1 and grain yield ?7.3 g pot^?1) was recorded with B_0.44 S_13.4 treatment combination. The combined applications of sulfur and boron yielded highest oil content with B_0.44S_13.4 (21.7%) treatment level. Chlorophyll ‘a’ and ‘b’ increased significantly with successive levels of sulfur and boron addition at 55 DAS. The mean sulfur and boron uptake in straw and grains increased significantly with increasing levels of sulfur and boron up to 13.4 mg kg^?1 and 0.44 mg kg^?1 and decreased non-significantly thereafter. At both the growth stages, a synergistic interactive effect of combined application of sulfur and boron was observed with B_0.44 S_13.4 treatment level for sulfur and boron uptake in straw and grains.     

QUARTZ PORPHYRY TREATMENT ALTERS IRRIGATION WATER CHEMISTRY,AFFECTING HYDROPONIC VEGETABLE PRODUCTION

This study focused on using quartz porphyry (QP) as a water treatment to improve hydroponic production of komatsuna (Brassica rapa L. nothovar; Japanese mustard spinach). We compared the chemistries of the control and QP-treated nutrient solutions and found that magnesium (Mg²⁺) and calcium (Ca²⁺) concentrations increased linearly up to day 21 following sowing in both conditions, then declined slightly. The QP treatment reduced sodium (Na⁺) and chloride (Cl^?) concentrations for the whole cultivation period. In both the control and QP-treated solutions, nitrate (NO^? ₃) and sulfate (SO^2? ₄) showed the same trend to a daily increase. In spite of these similarities, however, komatsuna production was better with the QP-treated nutrient solution compared to control. Treatment with QP during cultivation in August–September reduced the harmful effects of Na⁺, chloride (Cl^?), nitrite (NO^? ₂), and SO^2? ₄ by reducing concentrations of these ions, possibly leading to decreased salinity and toxicity effects in the plants. Mineral concentrations during October–November differed from those of August/September, resulting in variation among the different growth parameters for komatsuna.     

MAIZE RESPONSE TO YIELD AND YIELD TRAITS WITH DIFFERENT NITROGEN AND DENSITY UNDER CLIMATE VARIABILITY

To study yield and yield traits of maize, two experiments were conducted in 2006 as spring and summer crops and repeated in 2007. Three plant populations (43, 53, and 67 thousands ha^-1) and three nitrogen (N) rates (90, 120 and 150 kg N ha^-1) were compared in a completely randomized block design with split plot arrangement. The treatments plant population was assigned to the main and N to sub plots in three replications. Sowing of spring crop was done in March and harvested in July and likewise the summer crop in July and harvested in November. Each experimental unit comprised of 5 × 6 m area having eight rows spaced 0.75 m. Experimental results revealed that grain yield (GY) of summer was higher than spring season. Higher GY was associated with increases in the plant population and nitrogen rate. The treatment plant population of 53,000 and 67,000 ha^-1 did not differ. However, each increase in the N rate significantly increased GY. This increase in the GY by increasing N was due to increases in the ear length (EL), ear diameter (ED), grain number (GN) and thousand grain weight (TGW). Increasing plant population of maize did not show any remarkable changes in the yield traits. The study revealed that differences in GY due to seasonal climate cannot be rewarded with increase in either plant population or nitrogen rates. Moreover, spring and summer season maize crops can economically be planted with 150 and 120 kg N ha^?1 at 53,000 and 67,000 ha^?1 populations, respectively, to save environment and production cost.     

BIOMASS ALLOCATION AND NITROGEN DISTRIBUTION IN RYEGRASS UNDER WATER AND NITROGEN SUPPLIES

Ryegrass (Lolium perenne L.) in grassland is known to sustain with water and nitrogen (N). This study investigates biomass and N partitioning in plant organs (roots, main and the youngest tillers) under water-nitrogen interactions. Nitrogen was applied at the rates of 50 and 100 mg N kg^?1 as N₁ (low N) and N₂ (high N) treatments, respectively, with uniform irrigation until 440 growing degree-days (GDD). Thereafter, the water supply was restricted to 50 mL on a weekly basis (W₁) against 50 mL on a daily basis (W₂) and concurrently, N enriched with 1 atom% ¹⁵N isotopes. Cumulative tillers’ biomass increased linearly from 1st to 8th order, but thereafter reached a plateau with further increases in number of negligible weights. Initially tiller mass and number per plan did not differ (P < 0.05) with water and/or N applications but changed at 788 GDD with clear differences at 911 GDD with the highest under N₂W₂ and lowest under N₁W₁. Nitrogen concentration sharply decreased from 530 to 700 GDD and then levelled off with age. The decline was more pronounced in tillers than roots. The high N treatment showed elevated N-concentration under both water treatments. Watering on a daily basis promoted vegetative growth. High water and N levels significantly (P < 0.05) influenced concentration of N absorbed during ¹⁵N labeling (N_L) in all organs with relatively pronounced N_L under N₂. The additive positive effect of W₂ and N₂ was obvious on N_L as compared to N_T, which showed that plants discriminate N-uptake on mass basis. Nitrogen (mobile) was higher in young and ¹⁵N (heavier) was low in young tillers and vice versa. Accumulation of N absorbed during ¹⁵N labeling (¹⁵N_A) was significant knowing that water is a strong determining factor of N concentration in ryegrass organs.     

Nutrient Response of Water Hyssop to Varying Degrees of Soil Saturation

Tissue concentrations of nitrogen (N) and phosphorus (P) were measured in water hyssop (Bacopa monnieri) subjected to four progressive levels of flooding: well-drained Control, Intermittently Flooded, Partially Flooded, and Continuously Flooded. Soil redox potential (Eh), measured at two levels in the mesocosms decreased under flooding. Flooding increased biomass and decreased root growth and N and P concentrations in shoots, with the decreases being most pronounced in the Partially Flooded and Continuously Flooded treatments. The decreased uptake of N and P under flooding underscores the need to better understand how wetland plants function in nutrient-rich environments subjected to variable flooding. Additionally, the apparent decreased translocation of N and P from the root to the shoot in flooding conditions may be indicative of an overall decrease in mineral transport, which would have implications for the design and management of remediation systems.     

不同灌溉量下微水溶性缓释肥料在春玉米的肥效及环境效应研究

应用田间试验研究了适用于半干旱气候条件下的微水溶性缓释肥料(简称W,下同)在不同灌溉量下对春玉米生长的影响及环境效应。试验中设置了空白不施肥处理(CK)、常规灌溉尿素处理(N)、常规灌溉微水溶性缓释肥处理(W1)和减量灌溉微水溶性缓释肥处理(W2)。试验结果表明:与CK处理相比,W1处理显著提高了春玉米植株株高,W2处理显著提高了春玉米植株与籽粒全N、K含量及产量,但叶绿素、株高未显著提高,N处理仅显著提高了籽粒全N含量(p<0.05)。与N处理相比,W1处理显著提高了春玉米植株株高、肥料磷钾利用率与产量(p<0.05),土壤硝态氮残留峰值出现于80cm土层,淋失量显著减少(p<0.05);W2处理显著提高了春玉米植株与籽粒全N含量、肥料氮磷钾利用率与产量(p<0.05),土壤硝态氮残留峰值出现于60cm土层,淋失量显著减少(p<0.05)。由此说明,微水溶性缓释肥料具有一定的增产效果和节水功效,硝酸盐淋失量显著降低。     

EFFECTS OF PLANT GROWTH PROMOTING BACTERIA ON YIELD,GROWTH, LEAF WATER CONTENT,MEMBRANE PERMEABILITY,AND IONIC COMPOSITION OF STRAWBERRY UNDER SALINE CONDITIONS

Plant growth promoting effects of Bacillus subtilis EY2, Bacillus atrophaeus EY6, Bacillus spharicus GC subgroup B EY30, Staphylococcus kloosii EY37 and Kocuria erythromyxa EY43 were tested on strawberry cv. ‘Fern’ in terms of fruit yield, growth, chlorophyll reading value, leaf relative water content (LRWC), membrane permeability and ionic composition of leaves and roots under saline conditions. Compared with 0 mM sodium chloride (NaCl) treatment, the average decrease of yield and LRWC were 51.6% and 21.0%, respectively, when 35 mM NaCl was applied. However, EY30, EY37, and EY43 treatments under saline condition (35 mM NaCl) significantly increased fruit yield (54.4%, 51.7% and 94.9%) compared with 35 mM NaCl treatment without plant growth promoting bacteria (PGPB). The LRWC increased from 72.0% in 35 mM NaCl treatment to 88.4%, 86.6%, 84.2%, 83.5%, and 86.2% by EY2, EY6, EY30, EY37, and EY43 applications, respectively. The lowest membrane permeability among the bacterial strains was obtained from EY37 treatment (37) while it was 33 and 58 in 0 mM NaCl and 35 mM NaCl treatments, respectively. The concentration of all plant tissue nutrients investigated [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] with the exception of root phosphorus (P) and Mg concentration significantly decreased with 35 mM salt treatment. Nitrogen content of leaves varied between 3.04 and 3.14% in bacterial treatments under saline conditions while it was 2.71% in 35 mM NaCl treatment. In contrast sodium (Na) and chloride (Cl) of leaves and Cl content of roots were significantly decreased by root inoculation with all bacterial treatments in comparison to 35 mM NaCl treatment with no inoculation. Treatment with Bacillus EY30, Staphylococcus EY37 and Kocuria EY43 to strawberry plants can ameliorative the deleterious effect of salt stress on fruit yield, growth and nutrition. These results demonstrate that PGPB treatment could be offer an economic and simple means to increased plant resistance for salinity stress.     

EFFECT OF SALINIZATION OF SOIL ON GROWTH,WATER STATUS AND NUTRIENT ACCUMULATION IN SEEDLINGS OF ACACIA AURICULIFORMIS (FABACEAE)

Greenhouse experiments were conducted to assess the effects of salinization of soil on emergence, growth, water status, proline content, and mineral accumulation of seedlings of Acacia auriculiformis A. Cunn. ex Benth. (Fabaceae). Sodium chloride (NaCl) was added to the soil and salinity was maintained at 0.3, 3.9, 6.0, 7.9, 10.0, 12.1, and 13.9 dS m^?1. Salinity caused reduction in water potential of tissues, which resulted in internal water deficit to plants. Consequently, seedling growth significantly decreased with increase in soil salinity. Proline content in tissues increased with increase in salinity. Potassium and sodium content significantly increased in tissues as salinity increased. Nitrogen content significantly increased in tissues with salinization of soil. Phosphorus, calcium and magnesium content significantly decreased as salinity increased. Changes in tissues and whole-plant accumulation patterns of other nutrients, as well as possible mechanisms for avoidance of sodium toxicity in this tree species in response to salinity, are discussed.     

NATURAL ABUNDANCES OF 15NITROGEN AND 13CARBON INDICATIVE OF GROWTH AND N2 FIXATION IN POTASSIUM FED LENTIL GROWN UNDER WATER STRESS

Dual natural abundance analysis of ¹⁵Nitrogen (N) and ¹³Carbon (C) isotopes in lentil plants subjected to different soil moisture levels and rates of potassium (K) fertilizer were determined to assess crop performance variability in terms of growth and N₂-fixation (Ndfa). The δ¹⁵N values in lentils ranged from +0.67 to +1.36‰; whereas, those of the N₂-fixed and reference plant were ?0.45 and +2.94‰, respectively. Consequently, the Ndfa% ranged from 45 and 65% of total plant N uptake. Water stress reduced Δ¹³C values. However, K fertilization enhanced whole plant Δ¹³C along with dry matter yield and N₂-fixation. The water stressed plants amended with K fertilizer seemed to be the best treatment because of its highest pod yield, high N balance, and N₂-fixation with low consumption of irrigation water. This illustrates the ecological and economical importance of K fertilizer in alleviating water stress occurring during the post-flowering period of lentil.     

INTERACTIVE EFFECTS OF SALINITY AND N ON PEPPER (CAPSICUM ANNUUM L.) YIELD,WATER USE EFFICIENCY AND ROOT ZONE AND DRAINAGE SALINITY

The aim of this study was to determine the salt tolerance of pepper (Capsicum annuum L.) under greenhouse conditions and to examine the interactive effects of salinity and nitrogen (N) fertilizer levels on yield. The present study shows the effects of optimal and suboptimal N fertilizer levels (270 kg ha^?1 and 135 kg ha^?1) in combination with five different irrigation waters of varying electrical conductivity (EC) (EC_iw = 0.25, 1.0, 1.5, 2.0, 4.0, and 6.0 dS m^?1) and three replicates per treatment. At optimal N level, yield decreased when the irrigation water salinity was above EC_iw 2 dS m^?1. At the suboptimal N level, a significant decrease in yield occurred only above EC_iw 4 dS m^?1. At high salinity levels the salinity stress was dominant with respect to yield and response was similar for both N levels. Based on the results it can also be concluded that under saline conditions (higher than threshold salinity for a given crop) there is a lesser need for N fertilization relative to the optimal levels established in the absence of other significant stresses.     

全膜双垄沟不同覆膜时期对玉米土壤水分和产量的影响

针对甘肃省旱作农业区年降水量少、季节分布不均匀、玉米生产中春旱严重的问题,采用田间试验的方法研究了全膜双垄沟4种不同覆膜时期对旱地玉米生育时期、土壤水分变化、水分利用效率、产量及经济效益的影响。结果表明:秋覆膜优于早春顶凌覆膜、玉米播前覆膜和晚春播种时覆膜,即早覆膜优于晚覆膜。全膜双垄沟秋覆膜增加了降水利用率和水分利用效率,降水利用率为70.21%,产量为10039.34kg/hm2,比播前覆膜8036.67kg/hm2增产24.92%,水分利用效率36.01kg/hm2·mm,比播前覆膜27.10kg/hm2·mm提高32.88%。全膜双垄沟秋覆膜可明显减少冬春季土壤水分的无效蒸发,增产效果明显,是旱作区进一步挖掘降水潜力和高产田创建的有效途径。