Growth Of Alfalfa Plants Research Articles

Foliar Spray or Root Application: Which Method of Salicylic Acid Treatment is More Efficient in Alleviating the Adverse Effects of Salt Stress on the Growth of Alfalfa Plants, Medicago sativa L.?

Foliar Spray or Root Application: Which Method of Salicylic Acid Treatment is More Efficient in Alleviating the Adverse Effects of Salt Stress on the Growth of Alfalfa Plants, Medicago sativa L.?

Effect of artificial light on alfalfa (Medicago sativa L.) production

Objective: study the effects of different sources of artificial light on the growth of alfalfa plants (Medicago sativa L.).
 Design/Methodology/Approximation: The experiment was established on four shelves with a height of 2.50 m with three divisions each, each division 80 x 60 cm long and wide, respectively. In three of the upper divisions the sun's rays were allowed to penetrate, in the remaining nine divisions three different sources of artificial light (LED, incandescent and fluorescent) were placed, three divisions for each light source, at a density of four lamps per division. The energy expenditure per lamp, the intensity of photons and the production of dry matter were quantified.
 Results: The data indicated that the incandescent lamp had an energy expenditure 8 times higher than the LED lamp and 3.5 times higher than the fluorescent, however, the intensity of light emitted is 3 and 2 times higher in the LED lamp vs. incandescent and fluorescent. respectively, the highest production of dry matter was found with sunlight, obtaining values of 391 g m-2 and the lowest production with the incandescent lamp with 17 g m-2.
 Study limitations/Implications: It is necessary to continue carrying out research work on forage production with artificial light, to increase biomass yields.
 Findings/Conclusions: With the data obtained, it is concluded that LED light can be a viable alternative in the future to produce food for animal consumption.

Synergistic effect of Pseudomonas alkylphenolica PF9 and Sinorhizobium meliloti Rm41 on Moroccan alfalfa population grown under limited phosphorus availability.

This study looked at the synergistic effect of Pseudomonas alkylphenolica PF9 and Sinorhizobium meliloti Rm41 on the Moroccan alfalfa population (Oued Lmaleh) grown under symbiotic nitrogen fixation and limited phosphorus (P) availability. The experiment was conducted in a growth chamber and after two weeks of sowing, the young seedlings were inoculated with Sinorhizobium meliloti Rm41 alone or combined with a suspension of Pseudomonas alkylphenolica PF9. Then, the seedlings were submitted to limited available P (insoluble P using Ca3HPO4) versus a soluble P form (KH2PO4) at a final concentration of 250 μmol P·plant−1·week−1. After two months of P stress, the experiment was evaluated through some agro-physiological and biochemical parameters. The results indicated that the inoculation of alfalfa plants with Sinorhizobium strain alone or combined with Pseudomonas strain significantly (p < 0.001) improved the plant growth, the physiological and the biochemical traits focused in comparison to the uninoculated and P-stressed plants. For most sets of parameters, the improvement was more obvious in plants co-inoculated with both strains than in those inoculated with Sinorhizobium meliloti Rm41 alone. In fact, under limited P-availability, the co-inoculation with two strains significantly (p < 0.01) enhanced the growth of alfalfa plants evaluated by fresh and dry biomasses, plant height and leaf area. The results indicated also that the enhancement noted in plant growth was positively correlated with the shoot and root P contents. Furthermore, the incensement in plant P contents in response to bacterial inoculation improved cell membrane stability, reflected by low malonyldialdehyde (MDA) and electrolyte leakage (EL) contents, and photosynthetic-related parameters such as chlorophyll contents, the maximum quantum yield of PS II (Fv/Fm) and stomatal conductance (gs). Our findings suggest that Pseudomonas alkylphenolica PF9 can act synergistically with Sinorhizobium meliloti Rm41 in promoting alfalfa growth under low-P availability.

Productivity and Nutrient Content of the Second Regrowth Alfalfa (Medicago Sativa L.) with Different Photoperiod and Dolomite

The study was conducted to identify the effect of lighting duration and dolomite addition on the vegetative growth of alfalfa plants in second regrowth phase. The experiment was conducted in the greenhouse of the Laboratory of Forage and Pasture Science, Faculty of Animal Science, Universitas Gadjah Mada. It used a completely randomized design with 3x3-factorial using two factors and three replications. The first factor was lighting duration (C) with 3 levels (C0 = 12 hours, C1 = 14 hours, and C2 = 16 hours). The second factor was dolomite addition (D) with 3 levels (D0 = 0 ton/ha, D1 = 6 ton /ha, and D2 = 12 ton/ha). The results showed a significant effect so Duncan Multiple Range Test (DMRT) followed at 5% and 1% levels. The observed variables were plant height, the number of plant branches, the number of plant leaves, fresh forage production, and the chemical content of the plants in the form of dry matter (DM) and organic matter (OM). The addition of dolomite significantly affected the number of the plant branches, the number of plant leaves and the dry matter of the plants. A significant correlation was found between the two treatments and the number of leaves (C2D2) and a correlation was between the treatment and dry matter (C1D2).

Morphological effect of dichloromethane on alfalfa (Medicago sativa) cultivated in soil amended with fertilizer manures

In this work, we investigated the morphological effect of dichloromethane (DCM) on alfalfa (Medicago sativa) plant. We studied in vitro the influence of its concentration on alfalfa germination. The plants were placed in pots for 15 weeks, and exposed to increasing concentrations of DCM (50 µg L−1 and 84 mg L−1). In addition, we examined the effect of two manures (cow and sheep), which were applied to a contaminated soil, on alfalfa plant growth. The effect of the presence of dichloromethane is obvious even in plant–soil manure system. In fact, in the event of contamination, the soil–cow manure mixture represents the best setting medium for the Alfalfa plant compared to other environments, regardless of the contamination level. Indeed, the presence of two types of manure does not allow the suppression of the inhibitory effect of dichloromethane on the mass of the dry matter of the aerial part which is 18.38% for the cow manure-amended soil and 13.96% for the sheep manure-amended soil.

ВЛИЯНИЕ НЕФТЯНОГО ЗАГРЯЗНЕНИЯ НА РОСТ И ЭНДОМИКОРИЗУ ЛЮЦЕРНЫ

The influence of oil pollution on the growth and formation of arbuscular mycorrhiza in the roots of Medicago sativa plants was investigated. It was found that oil at low concentrations did not have an inhibitory effect on the growth of alfalfa plants. The length of the shoots of plants grown at an oil concentration of 1 g / kg of soil was 6.8% longer than that of plants grown in soil without oil. Improving plant growth with low oil concentrations in the soil may be associated with the addition of additional organic matter and mineral elements to the soil along with oil. The application of oil in higher concentrations led to the suppression of the growth of alfalfa plants. At a concentration of 20 g / kg and 50 g / kg of soil, the shoot length was 11.7% and 14.9% lower, respectively, than in the control plants. The main reasons for the delayed development of plants, stopping or their death as a result of oil pollution are disturbances in the flow of water and nutrients into plants, as well as developing oxygen starvation. We have revealed a change in the formation of endomycorrhizal symbiosis of the plant root system. In plants grown under oil pollution, the frequency of mycorrhization at a toxicant concentration of 1 g / kg, 20 g / kg, and 50 g / kg soil was lower by 2.0%, 26.5%, and 44.2%, respectively, according to compared with control plants (plants grown in soil without oil). Indicators of the intensity of colonization of mycorrhiza and the abundance of arbuscules in the root system of plants decreased, and the abundance of arbuscules in the mycorrhized part of the root fragment increased with an increase in the concentration of oil in the soil. Arbuscular mycorrhizal fungi, in addition to the direct toxic effect of pollutants, probably received less benefits from their plant partners, due to disruption of photosynthesis processes and redistribution of carbon substrates in favor of rhizosphere microorganisms.

Growth, Evapotranspiration, and Ion Uptake Characteristics of Alfalfa and Triticale Irrigated with Brackish Groundwater and Desalination Concentrate

Persistent drought, low snowfall, and low rainfall have reduced availability of fresh water for irrigating agricultural crops in many arid and semi-arid regions of the world. Brackish groundwater (electrical conductivity; EC &gt; 3 dSm−1) is increasingly used for irrigation in New Mexico. This study investigates the effect of ion uptake from brackish groundwater and concentrate irrigation on the performance of two forage species, alfalfa (Medicago sativa) and triticale (×Triticosecale), in sand soils in greenhouse conditions. Two simultaneous experiments were run for 90 days using tap water (control; 0.7 dSm−1), brackish groundwater (BGW; 4 dSm−1), reverse osmosis concentrate (RO; 8 dSm−1, Ca2+ dominant), and BGW plus sodium chloride (BGW + NaCl; 8 dSm−1, Na+ dominant). BGW + NaCl irrigation significantly reduced the evapotranspiration (ET) of both the species. Deep percolation (DP) increased significantly with RO and BGW + NaCl irrigation in alfalfa but only with BGW + NaCl irrigation in triticale. Alfalfa plant growth decreased with increasing salinity, while triticale plants followed an opposite trend. ET continued to decrease with increasing salinity for both species. Na+ dominant (BGW + NaCl) irrigation produced robust growth and early flowering and ear head formation in triticale. Na+ ion concentration in shoots was above 0.66%, which led to reduced alfalfa growth, while more than 1.22% did not decrease triticale growth or biomass. Increased Ca2+ sequestration in alfalfa played a crucial role in reducing Na+ ion toxicity. Species performance primarily confirmed that alfalfa is moderately salt-tolerant while triticale is confirmed to be a halophyte producing abundant growth and biomass with higher Na+ uptake. Triticale proved to be a promising species for reuse of RO concentrate for agriculture in marginal lands.

Effect of irrigation with saline water on ion homeostasis and forage dry yield in Alfalfa ecotypes application of high salty water for Alfalfa plants irrigation

Salinity stress is a brutal environmental stress which decreases the yield production of plants. Questions rise on which of the ionic stress or lack of water has deleterious effects on plants forage dry yield. Also, questions remain on whether the K+ reduction or Na+ accumulation is more important in forage dry yield reduction under salinity stress. The present experiment was conducted to answer the above questions in four alfalfa ecotypes. To do so, 6-7 weeks seedlings were irrigated with high salty water (EC=20dS m-1) and RWC, MSI, height, forage dry yield, Na+ and K+ were measured 1, 3, 6, 10, and 16 days after the salt shock. The results showed that one day after irrigation with saline water, all measured traits changed adversely. Salinity stress by decreasing K+ and increasing Na+ content reduced the growth of alfalfa plants. RWC reduction was less than K+ reduction or Na+ accumulation, so ionic stress had more deleterious effects on forage dry yield of alfalfa plants. Root cells had a higher content of K+ and Na+ ions compared with leaves, hence, they had a major defensive role against salinity stress. The K+/Na+ ratio reduction in saline condition was the main element for decreasing plant forage dry yield. The application of high salty water for irrigation of alfalfa plants is possible if there is a good subsoil drainage system to remove the leached saline water regularly from the soil. It is also suggested that foliar application of potassium may be ameliorate harmful effects of salinity stress in plant growth.

Heated blends of phosphate waste: Microstructure characterization, effects of processing factors and use as a phosphorus source for alfalfa growth

Microstructure of expandable lightweight aggregates (LWAs), which was composed of phosphate waste (PW), cement kiln dust (CKD) and raw clay (RC) was investigated, and the effects of processing factors (temperature, waste content, soaking time) on their physical properties were quantified by using response surface methodology (RSM). The potential use of LWAs as a phosphorus source was assessed through the use of seeds of alfalfa. It was found that the main minerals of the waste, namely carbonates and fluorapatite, were involved in the formation of labradorite/anorthite and melt respectively. Stability of mullite- the main constituent of CKD- was sensitive to the melt content. The assemblage of the identified phases was discussed based on the CaO-SiO2-Al2O3 phase diagram. The results of RSM showed that the change of compressive strength, firing shrinkage and water absorption of LWAs versus processing factors was well described with a polynomial model and the weights of the effects of the factors increased in the following order: sintering temperature > waste content (in the case of PW-RC) > soaking time. On the other hand, it was found that due to the release of phosphorus by soil-embedded pellets, the growth of alfalfa plants improved, and the rate enhanced in this order: PW-RC > PW-CKD > PW-CKD-RC. The absorbed quantity of phosphorus (0.12%) was still lower than the common uptake amount.

Co-expression of tonoplast Cation/H(+) antiporter and H(+)-pyrophosphatase from xerophyte Zygophyllum xanthoxylum improves alfalfa plant growth under salinity, drought and field conditions.

Salinity and drought are major environmental factors limiting the growth and productivity of alfalfa worldwide as this economically important legume forage is sensitive to these kinds of abiotic stress. In this study, transgenic alfalfa lines expressing both tonoplast NXH and H(+)-PPase genes, ZxNHX and ZxVP1-1 from the xerophyte Zygophyllum xanthoxylum L., were produced via Agrobacterium tumefaciens-mediated transformation. Compared with wild-type (WT) plants, transgenic alfalfa plants co-expressing ZxNHX and ZxVP1-1 grew better with greater plant height and dry mass under normal or stress conditions (NaCl or water-deficit) in the greenhouse. The growth performance of transgenic alfalfa plants was associated with more Na(+), K(+) and Ca(2+) accumulation in leaves and roots, as a result of co-expression of ZxNHX and ZxVP1-1. Cation accumulation contributed to maintaining intracellular ions homoeostasis and osmoregulation of plants and thus conferred higher leaf relative water content and greater photosynthesis capacity in transgenic plants compared to WT when subjected to NaCl or water-deficit stress. Furthermore, the transgenic alfalfa co-expressing ZxNHX and ZxVP1-1 also grew faster than WT plants under field conditions, and most importantly, exhibited enhanced photosynthesis capacity by maintaining higher net photosynthetic rate, stomatal conductance, and water-use efficiency than WT plants. Our results indicate that co-expression of tonoplast NHX and H(+)-PPase genes from a xerophyte significantly improved the growth of alfalfa, and enhanced its tolerance to high salinity and drought. This study laid a solid basis for reclaiming and restoring saline and arid marginal lands as well as improving forage yield in northern China.

The Productivity and Quality of Alfalfa (&lt;em&gt;Medicago sativa&lt;/em&gt; L.) in Romanian Forest Steppe

Alternative use of alfalfa, for various purposes, including the production of biofuels or food supplement for human alimentation, is a study topic still in its early stages of research. Studying and understanding the biology of alfalfa and the factors with a major influence on it are very important activities. The productivity and quality of alfalfa are two indicators that help determine, in addition to economic value, the way in which alfalfa can be used. Evolution of alfalfa yield and quality depends on many factors, such as the growth stage of alfalfa plants at harvesting. It was observed over three years of vegetation the influence of alfalfa plant growth stage at harvest on plant height, leaves/stems ratio, production of leaves, stems and whole plant (DM - dry matter) per hectare and on quality indicators (CP - crude protein, NDF - neutral detergent fiber and ADF - acid detergent fiber). The results showed that, with the advancement of phenological phases, from early bud stage to complete flowering, the total biomass output raised from 2.79 Mg·ha-1 to 4.60 Mg·ha-1, the neutral detergent fiber raised from 48.4-50.6% to 62.0-67.7%, while crude protein content decreased from 21.2-24.0% to 13.3-16.5%. The parameter values were correlated with alfalfa growth stage during the harvesting (significant at the 0.05 and 0.01 probability levels).

The Productivity and Quality of Alfalfa (Medicago sativa L.) in Romanian Forest Steppe

Alternative use of alfalfa, for various purposes, including the production of biofuels or food supplement for human alimentation, is a study topic still in its early stages of research. Studying and understanding the biology of alfalfa and the factors with a major influence on it are very important activities. The productivity and quality of alfalfa are two indicators that help determine, in addition to economic value, the way in which alfalfa can be used. Evolution of alfalfa yield and quality depends on many factors, such as the growth stage of alfalfa plants at harvesting. It was observed over three years of vegetation the influence of alfalfa plant growth stage at harvest on plant height, leaves/stems ratio, production of leaves, stems and whole plant (DM - dry matter) per hectare and on quality indicators (CP - crude protein, NDF - neutral detergent fiber and ADF - acid detergent fiber). The results showed that, with the advancement of phenological phases, from early bud stage to complete flowering, the total biomass output raised from 2.79 Mg·ha-1 to 4.60 Mg·ha-1, the neutral detergent fiber raised from 48.4-50.6% to 62.0-67.7%, while crude protein content decreased from 21.2-24.0% to 13.3-16.5%. The parameter values were correlated with alfalfa growth stage during the harvesting (significant at the 0.05 and 0.01 probability levels).

Ascophyllum nodosum Extract and Its Organic Fractions Stimulate Rhizobium Root Nodulation and Growth of Medicago sativa (Alfalfa)

The effects of the seaweed Ascophyllum nodosum extracts (ANE) on nitrogen (N)–fixing nodules and growth of alfalfa plants were studied under greenhouse conditions. The treatment of alfalfa roots increased the number of total nodules per plant with ANE (69%) and organic sub-fractions methanol (20%) and chloroform (35%) at 1 g L−1 concentration. The number of functional nodules was greater per plant in ANE (36%) and its organic sub-fraction chloroform (105%). Maximum increase in shoot length was observed in ANE-treated plants (42%) and chloroform-treated plants (42%). Root length was longer in the chloroform fraction (15%), whereas the shoot dry-weight accumulation was greater in plants treated with ANE (118%), methanol (85%), and chloroform (85%) than the control. Root dry-weight accumulation increased in plants treated with ANE (118%) and chloroform (69%) compared to the control. Further studies are under way to identify the chemical components in ANE and organic fractions.

THE INFLUENCE OF ARBUSCULAR MYCORRHIZAL FUNGI ON ALFALFA RESISTANCE AGAINST POLLUTION WITH HEAVY METALS AND ARSENICUM

The influence of the mycorrhizal infection by G. mosseae (Nicol. et Gerd.) Gerd et Trappe on the growth of Medicago sativa L. plants under different level of soil pollution with heavy metals (Zn, Pb, Cd, Cu) and arsenicum was studied. It was established the strongly increase of the growth and shoot biomass of mycorrhizal plants. The positive effect of mycorrhization on the growth of alfalfa plants was greater in the soils with the higher level of soil pollution with heavy metals and arsenicum.

Molecular evidence of genetic modification of Sinorhizobium meliloti: enhanced PCB bioremediation

The genome of the nitrogen-fixing soil bacterium Sinorhizobium meliloti does not possess genes for bioremediation of aromatic pollutants. It has the well-known ability to interact specifically with the leguminous alfalfa plant, Medicago sativa. Our previous work has shown enhanced degradation of the nitroaromatic compound 2,4-dinitrotoluene (DNT) when a plasmid containing degradative genes was introduced in it. In this study we report molecular evidence of the transfer of a polychlorinated biphenyl (PCB)-biodegradative plasmid pE43 to S. meliloti strain USDA 1936. Several standard analytical tests and plant growth chamber studies were conducted to test the ability of S. meliloti to degrade 2',3,4-PCB congener. Alfalfa plant alone was able to degrade 30% of PCBs compared with control. No enhanced dechlorination was noted when alfalfa plant was grown with wild-type S. meliloti, and when alfalfa plant was grown with the S. meliloti electrotransformants (genetically modified) dechlorination of PCBs was more than twice that when alfalfa plant was grown with wild-type S. meliloti. When alfalfa plant was grown with uncharacterized mixed culture (containing nodule formers), almost equally significant PCB degradation was observed. The significance of this work is that the naturally occurring nitrogen-fixing soil bacterium S. meliloti (genetically modified) has the ability to enhance fertility of soil in association with the leguminous alfalfa plant while simultaneously enhancing bioremediation of PCB-contaminated soils. Enhanced bioremediation of PCB and robust alfalfa plant growth was also noted when uncharacterized mixed cultures containing alfalfa plant nodule formers were used.

Impact of Bemisia whiteflies (Homoptera: Aleyrodidae) on alfalfa growth, forage yield, and quality.

A 3-yr project was initiated in 1993 to examine the effects of insecticides and sustained whitefly, Bemisia argentifolii Bellows & Perring [aka. B tabaci Gennadius (Strain B)], feeding on alfalfa plant growth and vigor in greenhouse cage studies, and to determine the impact of natural Bemisia whitefly populations on alfalfa forage yields and quality in a large-plot field experiment. Alfalfa plant growth and vigor after exposure to imidacloprid and a mixture of fenpropathrin and acephate insecticides did not differ from untreated plants in the greenhouse. Consequently, foliar and soil applied insecticides were used to manipulate whitefly densities on alfalfa plants to measure whitefly feeding effects on plant growth and forage yield. Heavy whitefly densities on untreated alfalfa plants in the greenhouse resulted in significant reductions in relative growth rates and net assimilation rates as compared with imidacloprid-treated plants that were maintained relatively whitefly-free. Reductions in alfalfa plant growth measured between infested and treated plants were proportional to whitefly densities. Field plot results derived from three crop seasons were relatively consistent with our greenhouse trials. Both experimental approaches clearly showed that alfalfa plants exposed to high densities of whitefly immatures and adults grew at a significantly slower rate and produced less foliage. As a result of reduced growth rates, alfalfa maturity in the naturally infested plots was estimated to be approximately 7-10 d behind managed plots. Delays in maturity resulted in significant reductions in forage yields of 13-18% during August-September harvests when whitefly populations reached peak abundance. Whitefly feeding stresses also effected hay quality through the reduction of crude protein content and contamination of foliage with honeydew and sooty mold. The status of the Bemisia whiteflies as an economic pest to alfalfa is clearly evident from these studies, but the damage potential of whiteflies in the southwestern United States appears to be restricted to one or two harvest periods during the summer coinciding with peak adult populations and their dispersal from alternate host crops.

The effects of NaCl and CaCl2 on photosynthesis and growth of alfalfa plants

The effects of 0, 30, 60, and 90 mM NaCl, and 0 and 5 mM CaCl2 on certain parameters of photosynthesis and growth in alfalfa (Medicago sativa L. cv. Ghara yonjeh) plants were studied. The increasing NaCl concentration in the Hoagland nutrient solution decreased the contents of chlorophylls and the net photosynthetic rate, and increased the rate of respiration (RD) and CO2 compensation concentration in the leaves of treated plants. The contents of carotenoids (Car) were not significantly affected. The addition of 5 mM CaCl2 enhanced the RD and increased the Car contents in treated leaves. With the NaCl concentration in the culture medium increasing, the dry matter production in both root and shoot decreased, as well as the relative growth rate (RGR), net assimilation rate (NAR), and leaf area ratio (LAR). The addition of CaCl2 caused a partial elimination of the NaCl effects on the root and shoot, RGR and NAR, and it decreased the LAR.

Effects of estrone and 17 β‐estradiol on vegetative growth of Medicago sativa

Alfalfa (Medicago sativa L.) plants were grown in the absence or presence of the steroidal estrogens, estrone and 17β‐estradiol, under varying conditions. Plants were analysed for the following parameters: plant weight, estrogen content, phytoestrogen content, degree of nodulation and nitrogen fixation activity. It was found that under controlled greenhouse conditions: (1) Treatment with estrogens in the range of 0.005 to 0.5 μg 1−1 increases both shoot and root dry weitht. In contrast, estrogen in concentrations of 50 to 500 μg 1−1 decreases plant growth. (2) The effect of estrogen of growth is most marked in the absence of nitrogen. (3) Estrone is more effective in increasing growth than 17 β‐estradiol. (4) In the plants where estrogen induced growth there was no significant increase in nitrogen fixation activity and nodule number. (5) Endogenous estrogen content of the plant did not increase at concentrations (0.005‐0.5 μg 1−1) which increased vegetative growth. (6) Endogenous estrogen content of the plant did increase at concentrations of estrogen (50‐500 μg 1−1 which inhibited vegetative growth and nodule weight. It can be concluded that estrogen in concentrations found in sewage water (0.3 μg estrogen 1−1) can affect the vegetative growth of alfalfa plants.

Effects of Chlorsulfuron onRhizobiumGrown in Pure Culture and in Symbiosis with Alfalfa (Medicago sativa) and Red Clover (Trifolium pratense)

The effect of chlorsulfuron on growth, infective ability, and symbiotic performance of legume bacteria was investigated. Bacterial growth in pure culture was unaffected by the addition of 0.55 and 5.5 μM chlorsulfuron. Early root hair infections of alfalfa by bacteria were inhibited by chlorsulfuron at 0.28 pM but not at 0.0028 pM in the root media. Inhibition of infection resulted from herbicidal effects on the root hair development. When inoculated red clover and alfalfa plants were grown in aseptic cultures in the presence of 0, 5.5, or 55 μM of chlorsulfuron, only 55 μM of herbicide inhibited the development and nodulation of plants. Early emergence and growth of alfalfa plants in soil supplemented with 2 × 10-6, 2 × 10-3, 2, 4, and 8 g/ha of chlorsulfuron were unaffected. However, 5 to 8 days after emergence plants grown in soil supplemented with 4 or 8 g/ha of chlorsulfuron were severely damaged, with no nodules developed. Nodulation occurred in plants grown in soil containing 2 × 10-3, 3 × 10-6, and 2 g/ha chlorsulfuron, but the nitrogenase activity of the nodules of these plants was less than for control plants. Plants grown in soil containing 2 g/ha of chlorsulfuron developed normally only after an initial growth inhibition of 5 to 6 weeks. The inhibition of nodulation and nitrogenase activity of nodules grown in the presence of chlorsulfuron is probably due to adverse effects of the herbicide on plant growth and development rather than on the rhizobia.

Dark transpiration rate and water deficit as growth limiting factors in alfalfa plants

Growth, dark transpiration rate (DTR) as well as water saturation deficit (WSD) of 30 single plants of 8 alfalfa genotypes growing in experimental field of 50 × 10 cm spacing, in four cuts at early bud stage, were studied. The growth and WSD of genotypes examined were significantly different, the differences in DTR were not significant. The growth of alfalfa plants was in negative correlation with both DTR which reflects non-effective water loss and WSD. Significant negative correlation established between plant growth and its variability shows that fodder productivity in alfalfa genotypes was dependent on growth variability of individual plants. Positive correlations established between WSD or DTR and the growth variability show some of the causes of growth variability.