Plant Root Dry Weight Research Articles

THE EFFECT OF PLANT GROWTH PROMOTING BACTERIA STRAINS ON YIELD AND SOME QUALITY PARAMETERS OF EGGPLANT (Solanum melongena L.)

This research was carried out under field conditions to determine the effect of PGPB on the yield and quality of Pulsar F1 eggplant variety under Igdir ecological conditions in 2021. The experiment was conducted with 8 treatments (Brevibacillus reuszeri strain IT 119, Kluyvera cyrocrescens strain IT 160, IT 119 + IT 160, IT 119 + Fertilizer, IT 160 + Fertilizer, IT 119 + IT 160 + Fertilizer, IT 119 + IT 160 + Fertilizer, Fertilizer and Negative Control) with 3 replications according to the randomized block design. Bacterial strains were applied by inoculating 100 ml (106 cfu/ml) to the root zone of the plants during seedling stage. PGPB treatments increased total yield, discard yield, marketable yield, plant height, plant stem thickness, number of leaves, plant root wet weight, plant root dry weight, stem wet weight, stem dry weight, number of fruits per plant, fruit wet weight, fruit dry weight and root length compared to negative and positive control groups. The treatments had no effect on fruit diameter. Although both strains were found to be successful, especially Kluyvera cyrocrescens strain IT 160 alone and in combination showed positive effects in terms of the parameters examined in eggplant plants and has the potential to be used as biofertilizer.

Exogenous Application of Humic Acid Mitigates Salinity Stress on Pittosporum (Pittosporum tobira) Plant by Adjusting the Osmolytes and Nutrient Homeostasis

AbstractImproving the physiological status expressed in adjusting the osmolytes and nutrients balance of plant cell is a crucial matter for ameliorating the hazards of salinity. In this context, humic substances have a significant role for stimulating the plant tolerance to various stresses. Therefore, the current study aimed to assess the importance of foliar spray of humic acid (0 and 150 mg L−1) for avoiding the effect of salt stress (0, 4000 and 8000 mg L−1) on vegetative growth of pittosporum plant, protein, proline, peroxidase activity and nutrient components related to salinity. The treatments were arranged in a randomized complete block design with 3 replicates. Results revealed that the highest vegetative growth was recorded with mg L−1 humic acid. While, salinity levels of 4000, and 8000 mg L−1 led to increases in protein, proline peroxidase activity, and chloride and sodium inions. Compared to humic acid-untreated plants, application of humic acid under salinity level of 4000 mg L−1 enhanced plant height, root fresh weight plant−1, root dry weight plant−1, shoot fresh weight plant−1 and shoot dry weight plant−1 by 12.6, 10.9, 17.7, 43.4, 19.4%, respectively, in the second season. Humic acid application under all salinity levels showed favorable effect for keeping leaves in both seasons, since fallen leaves number was reduced. The increases in potassium (K) content reached about 12.0 and 22.4% under 4000 mg L−1 and 8000 mg L−1, respectively, owing to humic acid application. Protein, proline content and peroxidase activity showed the minimal values under humic acid × salinity level of 4000 mg L−1. It could be concluded that application of humic mitigates the harmful effect of salinity and improves the vegetative growth parameters and physiological status of pittosporum plants while increases the uptake of beneficial nutrients.

Effects of Neem Leaf Extract on the Soil Properties, Growth, Yield, and Inorganic Nitrogen Contents of Lettuce

While lettuce offers essential human nutrients, it also contains anti-nutrients, particularly nitrate (NO3−). The use of neem leaf extract as a natural nitrification inhibitor has proven itself promising to remediate lettuce tissue NO3− content. This study evaluated the effects of neem leaf extract on soil properties, soil nitrification, lettuce growth, yield, and NO3− content. Five nitrification inhibitor treatments were evaluated: (i) no inhibitor (control), (ii) nitrapyrin, and three rates of neem leaf extract based on the dry weight of the raw material: (iii) 1 g kg−1 soil (Neem1), (iv) 2 g kg−1 soil (Neem2), and (v) 4 g kg−1 soil (Neem4). Neem leaf extract generally increased soil concentrations: P (47.6–55.8 mg kg−1), K (45.8–62.7 mg kg−1), Ca (129–164 mg kg−1), and Mg (29.0–35.7 mg kg−1) compared with the control (50.6 mg P kg−1, 35.3 mg K kg−1, 123 mg Ca kg−1, and 24.8 mg Mg kg−1). Neem leaf extracts significantly increased soil NH4+–N concentrations (13.9–30.2 mg kg−1) and nitrification inhibition (12.5–70.5%), but significantly decreased soil NO3−–N concentrations (6.4–13.2 mg kg−1) and net nitrification rates (0.08–0.23 mg N kg−1 day−1) relative to the control (6.6 mg NH4+–N kg−1, 14.7 mg NO3−–N kg−1, 0.26 mg N kg−1 day−1, and 0% nitrification inhibition). The neem leaf extracts significantly decreased shoot fresh weight (13.5–43.1 g plant−1), shoot dry weight (0.84–3.91 g plant−1), and root dry weight (0.14–0.27 g plant−1) compared with the control (52.3 g shoot fresh weight plant−1, 5.36 g shoot dry weight plant−1, and 0.35 g root dry weight plant−1). The significant decreases in the lettuce biomass in the neem extract treatments paralleled the significant decreases in the shoot’s tissue NO3−–N contents and significant increases in tissue NH4+–N content and soil Al concentrations.

Root pruning is effective in alleviating the inhibition of soybean growth caused by anaerobic stress for a short period

Soybean is an important upland crop, but its productivity is often limited by anaerobic stress caused by waterlogging. The ability to adjust root growth under environmental constraints is an important physiological trait for adapting to an ever-changing environment, and root pruning is an artificial technique for regenerating the root system. In the present study, we investigated whether root pruning in soybean can effectively alleviate the inhibitory effects of anaerobic stress. Soybean plants were affected by anaerobic stress at the germination, vegetative stage 1 (V1), and reproductive stage 1 (R1) stages, and then the plants were treated with root pruning just after the stress treatment. Soybean plants at the germination stage were treated with root cap and tip removals after hypoxia (N2 treatment). Root cap removal was more effective in suppressing the inhibitory effects of hypoxia than root tip removal (5 mm from the tip). The shoot dry weights of the soybean plants with and without root cap removal after hypoxia were 51.2 and 73.8% of the control, respectively, while the root dry weights of plants with and without root cap removal after hypoxia were 43.2 and 62.8% of the control, respectively. As root cap removal effectively enhanced soybean growth after anaerobic stress, the root cap may be the candidate tissue for the stress memory mechanism. When soybean plants at the V1 stage of growth were affected by anaerobic stress, the branch number, pod weight in the main stem, root length, and root surface area of the soybean plants treated with anaerobic stress at the R1 stage significantly decreased compared with those of the control. In contrast, root pruning (2 mm from the tip) immediately after the stress treatment enhanced root growth, branch number, and pod weight. The branch number, pod weight, root length, and root surface area of the plants treated with root pruning were 1.13, 1.14, 1.12, and 1.13 times higher than those of plants treated with anaerobic stress. Plasmolysis was observed in the root meristem, columella, and cortical cells in soybean roots subjected to anaerobic conditions. However, damage was not observed in the newly emerged roots after root pruning in plants treated with anaerobic stress. These results suggested that root pruning is effective in enhancing soybean growth after anaerobic stress. This effectiveness may be due to the regeneration and elongation of healthy lateral roots during the recovery period. When soybean plants were affected by anaerobic stress at the R1 stage, root pruning just after the stress treatment was ineffective. Thus, suppressing the growth reduction due to anaerobic stress at reproductive stages using only root pruning may be difficult.

Effects of Biochar and Biochar–Compost Mix on Growth, Performance and Physiological Responses of Potted Alpinia zerumbet

Container crop production has become increasingly popular over the last 50 years. A major component of container or potting media is peat. Peatlands are a natural carbon sink, and peat is a nonrenewable natural resource. Peat harvesting has become an important environmental issue. There is a growing effort to explore alternative organic materials to completely or partially replace peat as a medium component. Biochar is a carbon-rich product that has gained increasing interest as a component of growing media. In the present study, biochar was produced from rice straw. Peat/perlite/biochar (PPB; 40/30/30 v/v) and peat/perlite/biochar/vermicompost (PPBC; 30/30/35/5 v/v) were evaluated relative to a basal or control medium of peat/perlite (PP; 70:30 v/v). Alpinia (Alpinia zerumbet ‘Variegata Dwarf’) was used as a test plant. Amending biochar and biochar–compost mix increased the pH of the growing media. Hydrophysical properties including container capacity, bulk density, air space and total porosity were all within or near the standard ranges for soilless growing media. Chlorophyll a and b contents of A. zerumbet plants grown in PPB medium were reduced by more than 20% and 28%, respectively, compared to those grown in PP or PPBC media. The net photosynthetic rate of PPB-grown plants was more than 28% lower than those grown in PP and PPBC media. As a result, shoot and root dry weights of plants produced in PPB medium were more than 42% and 22% less, respectively, than those grown in PP and PPBC media. Although visual quality of PPB-grown plants was lower, they still exhibited marketable quality, which was largely due to the fact that their side shoots, leaf numbers, leaf areas, leaf thickness, and shoot diameters were comparable to those produced in PP and PPBC media. The present study showed that in a peat/perlite basal medium, substitution of peat by biochar derived from rice straw at 30% affected the growth of A. zerumbet plants, mainly in dry matter accumulation, but the plants were still marketable. On the other hand, plants grown in the same basal medium with peat replaced by the biochar at 35% plus an amendment of compost at 5% were comparable to those grown in the control medium. As the value of ornamental plants depends on their aesthetic appearance, a potting medium comprised of peat/perlite/biochar/vermicompost at 30/30/35/5 by volume is recommended for the production of A. zerumbet plants. The substitution of peat at 35% suggests that peat use can be reduced in the formulation of potting media, thus contributing to the conservation of peatlands.

Compost mixed fruits and vegetable waste biochar with ACC deaminase rhizobacteria can minimize lead stress in mint plants

High lead (Pb) concentration in soils is becoming a severe threat to human health. It also deteriorates plants, growth, yield and quality of food. Although the use of plant growth-promoting rhizobacteria (PGPR), biochar and compost can be effective environment-friendly amendments for decreasing Pb stress in crop plants, the impacts of their simultaneous co-application has not been well documented. Thus current study was carried, was conducted to investigate the role of rhizobacteria and compost mixed biochar (CB) under Pb stress on selected soil properties and agronomic parameters in mint (Mentha piperita L.) plants. To this end, six treatments were studied: Alcaligenes faecalis, Bacillus amyloliquefaciens, CB, PGPR1 + CB, PGPR2 + CB and control. Results showed that the application A. faecalis + CB significantly decreased soil pH and EC over control. However, OM, nitrogen, phosphorus and potassium concentration were significantly improved in the soil where A. faecalis + CB was applied over control. The A. faecalis + CB treatment significantly improved mint plant root dry weight (58%), leaves dry weight (32%), chlorophyll (37%), and N (46%), P (39%) and K (63%) leave concentration, while also decreasing the leaves Pb uptake by 13.5% when compared to the unamended control. In conclusion, A. faecalis + CB has a greater potential to improve overall soil quality, fertility and mint plant productivity under high Pb soil concentration compared to the sole application of CB and A. faecalis.

NITROGEN RATES AND RESIDUAL EFFECT OF CO-INOCULATION OF SOYBEAN ON MAIZE PLANTS

ABSTRACT Co-inoculation consists of using microorganism combinations with synergic effect that surpass the results obtained with their use alone. The objective of this work was to evaluate the effect of inoculation and co-inoculation on soybean plants, and their residual effect on maize plants grown intercropped with ruzigrass (Urochloa ruziziensis), under different N fertilizer rates. The experiment was conducted at the experimental area of the Mato Grosso State University, Alta Floresta campus, in a Typic Hapludox. A randomized block design was used for the soybean crops; the treatments consisted of Bradyrhizobium japonicum inoculated single, or co-inoculated with Azospirillum brasilense, with 20 replications. A randomized block design in a strip-plot arrangement was used for the winter maize-ruzigrass intercrop (WMRI); the treatments consisted of combination of residual effect of inoculation and co-inoculation in the strips, and five N fertilizer rates (0, 50, 100, 150, and 200 kg ha-1) in plots with WMRI, with four replications. The co-inoculation of soybean seeds and its residual effect on the maize crops increased the root dry weight of plants of both crops; however, no increases were found for most vegetative and reproductive characteristics of maize plants. Yield and most characteristics evaluated had increasing linear responses to increases in N rates, indicating the plants could respond to rates above 200 kg ha-1.

Identification and evaluation of high nitrogen nutrition efficiency in rapeseed (Brassica napus L.) germplasm

To establish identification and evaluation methods of N (nitrogen) absorption and utilization of rapeseed (Brassica napus L.), difference of N nutrition efficiency (NNE) among rapeseed germplasms and relationship between NNE and plant traits under various N application rates were analyzed in this research. Pot cultivating experiments were conducted to investigate NNE with 3 ​N application rates in soil (0.05, 0.2 and 0.3 ​g/kg). A total of 12 rapeseed germplasms were planted, nitrogen absorption efficiency (NAE) and nitrogen utilization efficiency (NUE) in seedling stage, bolting stage, initial flowering stage, final flowering stage, and maturity stage were obtained. Results showed that bolting stage was the best period for NAE identification and evaluation. Low N application rate in soil (0.05 ​g/kg) was the best for NAE, and the indirect indexes were basal stem diameter, plant root dry weight and above ground plant dry weight. Maturity stage was the best period for NUE identification and evaluation. High N application rate in soil (0.3 ​g/kg) was the best for NUE, and indirect indexes were above ground plant dry weight and basal stem diameter. N application rates of 0.05 ​g/kg in soil was the best for nitrogen harvest index at maturity stage, and indirect indexes was number of pods per plant. Plant traits of rapeseed germplasms affected NNE. Higher basal stem diameter, plant root dry weight and above ground plant dry weight at bolting stage under low N application rate were important characteristics of N absorption in rapeseed. Higher above ground plant dry weight and basal stem diameter at maturity stage under high N application rate were important characteristics of N utilization. Higher number of pods per plant at maturity stage under lowe N application rate was an important characteristic of N harvest index. These results provided a reliable index for N management and provided theoretical basis for guiding rapeseed breeding.

Fertilizer Management for Improving Water Use Efficiency in Winter Cereals in Semiarid Region of Northwest, Pakistan

The pot experiment was conducted at Agronomy Farm of the University of Agriculture, Peshawar during winter 2015–2016 to study the impact of Fertilizers management for improving water use efficiency in winter cereals. The experiment was laid out in CRD having four replications. The experimental treatments consisted of crops (wheat and oats), fertilizers sources T1 (control), T2 (NpK @ 90 : 60 : 0 Kg ha–1), T3 (FYM @ 10 ton ha–1), T4 (biochar @ 10 ton ha–1), T5 (FYM @ 10 ton ha–1 + biochar (@ 10 ton ha–1) and three stages (5th Jan, 12th Jan, 19th Jan). Different fertilizer sources had significantly affected all parameters except days to emergence. Fertilizer NPK had significantly increased emergence m–2 (1133.45 m–2), plant height (22.2 cm), leaf area plant–1 (58.4 cm2), LAI (6.6), root fresh weight plant–1 (127.9 mg), root dry weight plant–1 (22.5 mg), shoot fresh weight plant–1 (748.8 mg), shoot dry weight plant–1 (131.7 mg), biomass plant–1 (154.2 mg), Soil pH (8.16) and water use efficiency (20.1 kg ha–1 mm–1), whereas FYM + biochar had maximum root length (9.8 cm). In crops Oat had significantly more emergence (1037.24 m–2), plant height (23.3 cm), root to shoot ratio (2.7), root fresh weight plant–1 (110 mg), root dry weight plant–1 (20.1 mg), shoot fresh weight plant–1 (778.7 mg), shoot dry weight plant–1 (138.5 mg), biomass plant–1 (158.5 mg) and WUE (18.7 kg ha–1 mm–1), while higher, root length (9.4 cm), leaf area plant–1 (46.6 cm) and LAI (4.8) was recorded from wheat. Stage three (19th Jan) had significantly more plant height (22.4 cm), root length (9.9 cm), leaf area plant–1 (62.5 cm2), LAI (6.5), root fresh weight plant–1 (133.3 mg), root dry weight plant–1 (27.8 mg), shoot fresh weight plant–1 (803 mg), shoot dry weight plant–1 (163 mg), biomass plant–1 (190.8 mg) and WUE (18.4 kg ha–1 mm–1). In C × S, oats at stage three produced higher root fresh weight (153.8 mg), root dry weight (33.1 mg), shoot fresh weight (1091.3 mg), shoot dry weight (225.2 mg), biomass (258.3 mg) and WUE (25.1 kg ha–1 mm–1). The interaction of with C with T, oats treated with NPK produced maximum shoot dry weight (164.9 mg), biomass (188.2 mg) and WUE (22.8 kg ha–1 mm–1). In S × T, at stage three (19th Jan) with the application of NPK had produced more leaf area plant–1 (90.7 cm2), LAI (10.3), biomass (215.8 mg). Based on the results oats treated with inorganic fertilizer have higher WUE. Inorganic fertilizer improves plant WUE.

Glyphosate impact on C and N microbial functional groups in soybean rhizosphere

The no-tillage system requires a higher use of herbicides to control weeds before sowing, increasing the concern over the effect that such products might have on the environment. However, few studies reporting the influence of glyphosate on soil microorganisms are available in the literature. The aim of this work was to evaluate the effect of two formulations of glyphosate on functional groups of microorganisms in soybean rhizosphere. The experiment was performed in a greenhouse, and the treatments were the isopropylamine salt and the ammonium salt of glyphosate at the maximum and twice the maximum allowed dose. The control treatment had no application. The populations of soil bacteria, fungi, actinomycetes, fluorescent pseudomonas, cellulolytics, amylolytics, proteolytics and free-living N-fixing were determined by plate counts on selective media. Plant root dry weight, shoot dry weight and the number and dry weight of nodules were determined. The application of herbicides had little effect on the populations of microorganisms, as well as on plant growth. Nevertheless, the interactions among some populations of microorganisms and between these and the plant were influenced by the formulation of the glyphosate applied.

Strong effect of recovery period between hypoxia events on roots of chickpea (Cicer arietinum L)

Hypoxia as an environmental stress affects the physiological, metabolic, and anatomical parameters in plants. This experiment was conducted in order to evaluate the changes of these parameters in chickpea roots in response to hypoxia followed by recovery. With this aim, two periods of hypoxia (two and four days) and recovery subsequent (one and three days) were applied on chickpea roots in a hydroponic condition. Hypoxic condition significantly decreased the root dry weight of plants. However, the contents of anthocyanins, flavonoids, malondialdehyde (MDA), hydrogen peroxide (H2O2), as well as the activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX)) were increased by hypoxia. In addition, anatomical changes were observed in the chickpea roots under the hypoxia and recovery treatments. Under the hypoxic condition, root's aerenchyma began to form and the thickness of the Casparian strip was decreased. Interestingly, the one-day recovery following two or four days of hypoxia could not reduce the hypoxia effects on the chickpea roots. In contrast, the three-day recovery period partly reduced the adverse effect of hypoxia. The pattern of physiological, metabolic, and anatomical changes during the recovery period following the four-day hypoxia was similar to the recovery period following the two-day hypoxia. These findings display a negative effect of hypoxia and one-day recovery following hypoxia on different parameters of chickpea roots. Nevertheless, prolonging the period of recovery (three-day recovery) has a positive effect on the chickpea roots after exposure to hypoxia.

Growth of the Aquatic Plant Southern Naiad in Varying Percentages of Sand and Controlled-release Fertilizer

Native aquatic plants are important to maintaining a balanced ecosystem, but they often are displaced by exotic invasive plant species. The research on the control and growth of the invasive aquatic species hydrilla (Hydrilla verticillata) using sand substrates and controlled-release fertilizers (CRF) provides a potential production technique for other aquatic plants. We questioned if we could use hydrilla production techniques to grow southern naiad (Najas guadalupensis), a Florida-native aquatic plant that is often mistaken for hydrilla. We grew southern naiad cuttings in containers filled with 100:0, 75:25, 50:50, 25:75, or 0:100 coarse builder’s sand and sphagnum moss (by volume). Before planting, containers were fertilized with 0, 1, 2, or 4 g·kg−1 CRF (15N–4P–10K). Containers were submerged in large storage tubs filled with rainwater and grown for 8 weeks. Southern naiad shoot dry weight was greater in the 100% sand substrate than that in the 0% sand substrate. Substrate electrical conductivity (EC) levels were greater in the 0% sand with no difference among the other substrates. Shoot and root dry weight of plants fertilized with 1–2 g·kg−1 CRF were greater than 0 or 4 g·kg−1 CRF. Substrate EC also increased as fertilizer rate increased, with the highest EC observed at 4 g·kg−1 CRF. Based on our results, we would suggest growing southern naiad in substrates with 100% sand and fertilized with 1–2 g·kg−1 CRF.

Exogenous application of nitric oxide and spermidine reduces the negative effects of salt stress on tomato

Due to increasing soil salinity, the world agricultural output is being threatened by the shrinking area of fertile land. In the present study, we explored the interactive roles of nitric oxide (NO; 100 μM) and spermidine (SP; 200 μM) in ameliorating the effects of salt stress (NaCl; 100 mM) in tomato (Solanum lycopersicum L. var. Five Star) seedlings. NaCl stress reduced shoot and root length, shoot and root fresh weight, shoot and root dry weight plant -1 and leaf area leaf -1. NaCl stress also suppressed the biosynthesis of photosynthetic pigments (Chlorophyll a and b) and increased proline (Pro) content, membrane damage and lipid peroxidation by inducing reactive oxygen species (H2O2 and O2• - ) generation in roots and leaves, as well as electrolyte leakage (EL) and malondialdehyde (MDA) accumulation in leaves. However, applying NO and/or SP increased the activities of catalase, peroxidase, superoxide dismutase, glutathione reductase and ascorbate peroxidase and increased photosynthetic pigment (chlorophyll a and b) and Pro accumulation, as well as reducing H2O2 and O2• - and MDA content and EL, under salt stress. When tomato plants were treated with NO and SP simultaneously, NO signaling was further enhanced, which was confirmed by the addition of cPTIO [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; NO scavenger].

Titanium Dioxide Nanoparticles Improve Growth and Enhance Tolerance of Broad Bean Plants under Saline Soil Conditions

AbstractSoil salinity is established as one of the major environmental problems, decreasing crop productivity worldwide, thereby threatening sustainable agriculture. In the present study, we evaluated the effects of titanium dioxide nanoparticles (nTiO2) for ameliorating soil salinity in broad bean, an important leguminous crop. As nTiO2 is known to have pro‐oxidant and antioxidant properties, the effects of three different nTiO2 concentrations (0·01%, 0·02% and 0·03%) were compared with respect to plant growth and stress responses. The 0·01% nTiO2 application significantly increased shoot length, leaf area and root dry weight of plants under normal conditions. These growth‐promoting effects were simultaneous with increased levels of chlorophyll b, soluble sugars and proline and enhanced activities of antioxidant enzymes. Under saline soil conditions, although proline level and enzymatic antioxidant activities were increased, plant growth significantly reduced. The 0·01% nTiO2 supplementation significantly increased the activities of enzymatic antioxidants and levels of soluble sugars, amino acids and proline in salt‐affected plants versus plants subjected to salinity alone. Thus, the increased antioxidant enzyme activities contributed to the observed reduction in hydrogen peroxide and malondialdehyde contents, while enhanced levels of proline and other metabolites contributed to osmoprotection, collectively resulting in significant plant growth improvement under salinity. Furthermore, nTiO2‐mediated positive effects were concentration dependent with 0·01% nTiO2 being the most effective, whereas 0·02% showed an intermediate response and 0·03% was almost ineffective under both control and saline soil conditions. Our findings provide a foundation for nTiO2 application in improving growth of plants cultivated on naturally contaminated saline soils. Copyright © 2017 John Wiley & Sons, Ltd.

Evaluation of seed soaking times on germination percentage, germination rate and growth characteristics of pistachio seedlings

In traditional pistachio cultivation, prior to sowing seeds the latter are soaked in water for different times as farmers claim that this will contribute to germination. To our best knowledge, this is the first attempt to evaluate the effect of different water-soaking time periods on germination in pistachio. For this purpose, seeds of pistachio (P. vera L. 'Badami') were treated with water for 1, 6, 12 and 24 h. We monitored germination percentage, germination rate, mean time for germination rate, and seedling height at different stages, number of leaves, shoot and root dry weight, and trunk diameter. Our results indicated that germination percentage and rate significantly increased and seedling height increased in seeds, which were treated for 24 h. Although, plant root dry weight significantly decreased in seeds of this treatment, mean times for germination (MTG) values were not found to be statistically significant between treatments. We observed that the 6 h soaking treatment led to an increase in shoot and root dry weight, and trunk diameter. Also leaf numbers and root length values were highest in the 1 h soaked seeds, although differences were not significant. Positive relationship was observed between the plant shoot length and plant leaf number.

THE EFFECT OF ELEVATED CO2 ON THE VEGETATIVE AND GENERATIVE GROWTH OF PHALAENOPSIS

Phalaenopsis is a crassulacean acid metabolism (CAM) plant which absorbs and binds CO2 as malate during the night. During daytime the stomata close and the CO2 stored in the vacuole is released and used for photosynthesis. Because the CO2 taken up by CAM plants was assumed to be unaffected by the CO2 concentration in the air, additional CO2 for increased growth was generally not supplied in Phalaenopsis. However, a literature study indicated that elevated CO2 might have a positive effect in Phalaenopsis. To assess the effects of elevated CO2 concentrations in Phalaenopsis, two experiments were performed with elevated CO2. In the first experiment, 8 Phalaenopsis clones were induced to flower at 400 and 1000 ppm CO2 in the greenhouse at day/night temperatures of 19.2/18°C. Two or more spikes were produced by 82% of the plants grown at 1000 ppm CO2, and in 70% of the plants grown at 400 ppm CO2. The mean number of spikes per plant was 9% higher and their dry weight was 12% higher. A second experiment was then designed to see if the effect of elevated CO2 was limited to the flowering phase, or was effective during the vegetative phase as well. In this experiment, four Phalaenopsis clones were grown in climate controlled growth chambers at CO2 concentrations of 400 or 1000 ppm. During the vegetative growth phase (30 weeks), the leaf area and root dry weight of plants grown at elevated CO2 appeared to be higher than at low CO2. At the end of the vegetative growth phase, plants from both CO2 treatments were split into two groups: one group at low CO2 and the other at elevated CO2 for the generative growth phase, resulting in 4 treatment groups. Day/night temperatures were lowered to 19/18°C for 6 weeks to induce spiking followed by 12 weeks with day/night temperatures of 21/19°C during the growth and development of the spikes. Plants grown at elevated CO2 during the generative growth phase yielded 15 and 10% more plants with multiple spikes and an improved flower stem quality, when grown at low and high CO2 in the vegetative phase respectively. Elevated CO2 during the vegetative growth phase had no significant effect on the number of spikes, but the trend indicates an increase in spike quality.

Reduced severity and impact of Fusarium wilt on strawberry by manipulation of soil pH, soil organic amendments and crop rotation

Strawberry (Fragaria × ananassa) is one of the most important berry crops worldwide. Fusarium wilt poses a serious threat to commercial strawberry production worldwide and causes severe economic losses. Our previous surveys suggested that soil pH, soil amendment with organic matter and/or crop rotation could offer opportunities for improved management of strawberry disease. Studies were conducted for the first time to determine the effects of soil pH, soil amendments with manure compost and crop residue, and crop rotation on the severity and impact of Fusarium wilt on strawberry. At soil pH 6.7, plants showed the least severe disease and the lowest reductions in shoot and root dry weight (DW) of plants from disease, significantly lower than those of plants in acidic soil at pH 5.2 or 5.8. In soil amendment with manure compost at 5.0 %, plants showed the least severe disease and the lowest reductions in shoot and root DW of plants from disease, significantly lower than those of plants in the other three levels of manure compost. In soil amendment with crop residue at 2.5 % or 5.0 %, shoot and root disease of plants and reductions in shoot and root DW of plants from disease were significantly lower than those of plants in soil without crop residue or excessive crop residue amendment at 10.0 %. Plants in soil rotated with tomato not only showed the least severe disease but also showed the lowest reductions in shoot and root DW of plants from disease, significantly lower than those of plants in soil continuously planted with strawberry without rotation or rotated with capsicum. Soil pH, soil amendment with manure compost or crop residue, and crop rotation, all significantly reduced the severity and impact of Fusarium wilt on strawberry. There is great potential for manipulating soil pH, adding soil organic amendments and utilizing crop rotation, not only to successfully manage Fusarium wilt on strawberry, but to do so in a sustainable way without current reliance upon chemical fumigants.

Effects of Using Water Treated by Artificial Wetlands on Root Rot Suppression and Tomato Growth

The objectives of this study were to evaluate the risks and benefits of using artificial wetland-treated waters to irrigate tomato plants (Lycopersicom esculentum) and the potential for suppression of Pythium ultimum. The experiment was conducted in a greenhouse using tap water (control) and treated waters coming from three types of horizontal subsurface flow artificial wetlands filled with pozzolana and implanted with common cattail (Typha latifolia). Wetland units contained either a simple [artificial wetland with sucrose (AWS)] or complex [artificial wetland with compost (AWC)] carbon source or no [artificial wetland with no carbon (AW)] additional carbon source. A complete randomized split-block design comparing root sensitivity to root rot (inoculated and uninoculated plants) in main plots and four nutrient solutions [1) control, 2) treated water from AWS, 3) treated water from AWC, and 4) treated water from AW] in subplots was used in six replications. Tomato plants were inoculated with P. ultimum twice during the experimental period. The use of treated waters reduced the in vivo root Pythium population by 84% and 100% when the treated waters were from AWS and AWC, respectively. In vitro trials showed that sterilization or membrane filtration (0.2 μm) of treated waters significantly reduced the potential for suppression of P. ultimum, suggesting that microbial activity played an important role. On the other hand, all AW-treated waters had a negative effect on root development of uninoculated young tomato plants. Root dry weights of plants irrigated with treated waters was 56% lower than in control plants, while their shoot:root ratio was two times higher for plants irrigated with treated waters. The inoculated and AWC-treated water treatments also reduced the Fv:Fm ratio of dark-adapted leaves, representing the maximum quantum efficiency of photosystem II. Organic compounds present in treated waters, expressed as total and dissolved organic compounds, may have affected tomato root development.

Effect of salinity and seed priming on growth and biochemical parameters of different barely genotypes

An experiment was conducted to investigate the interactive effect of salinity and seed priming on barely genotypes at the Institute of Biotechnology and Genetic Engineering (IBGE), Khyber Pakhtun Khwa Agricultural University Peshawar Pakistan. The experiment was carried out in completely randomized design (CRD) with three replications consisting of twelve barely genotypes (Haider-93, Soorab-96, Arabic Asward, NRB-37, Frontier-87, Jau-83, Balochistan-Local, NRB-31, KPK-Local, Sanober-96, Awarn-2002 and AZ-2006) at two seed conditions (seed priming with 30 mM NaCl or no seed priming) under four salinity levels (0, 50, 100 and 150 mM). The results revealed that seed priming and salinity had significantly (p≤0.05) affected all the parameters under study. However, the effect of seed priming was non significant (p>0.05) on shoot chlorophyll a content (mg g -1 fresh weight) and root sugar content (mg g -1 dry weight). Salinity stress had adversely affected growth and biochemical parameters of barley genotypes, however, seed priming with NaCl had diminished the negative impact of salt stress. Maximum shoot dry weight plant -1 (1.81 g), root dry weight plant -1 (0.42 g), shoot K + content (1.41 mg g -1 dry weight), root sugar content (7.55 mg g -1 dry weight) were recorded in Balochistan-Local. Similarly, Haider-93 produced highest root K + content (0.67 mg g -1 dry weight), shoot sugar content (16.36 mg g -1 dry weight), shoot chlorophyll a content (3.44 mg g -1 fresh weight) and shoot chlorophyll b content (1.78 mg g -1 fresh weight). Maximum shoot Na + content (1.20 mg g -1 ) and root Na + content (1.47 mg g -1 ) was recorded in Frontier-87. Seed priming had significantly (P<0.05) enhanced all the aforementioned parameters. The positive effect of seed priming was more profound in Balochistan-Local followed by Haider-93 as compared to other genotypes. Key words : Barely, salinity, seed priming, Na + , K + , chlorophyll a and b.

Effects of the application of ‘cash’ on the growth, fruit yield, and nutrient status of tomato (Solanum lycopersicum L.) grown in reclaimed saline soil

SummaryThe effects of ‘cash’ [a novel 2:5:1 (w/w/w) mixture of calcium sulphate, ground sunflower heads, and humic acid] as a soil amendment on the growth, fruit yield, and leaf nutrient status of tomato (Solanum lycopersicum L.) grown on reclaimed saline soil (EC = 9.4 dS m–1) were investigated. A glasshouse experiment was performed in a completely randomised design with six treatments (0, 10, 20, 30, 40, or 50 g ‘cash’ kg–1 soil) each with four replicates. The results indicated that ‘cash’ increased both the shoot dry weight (DW) plant–1 and the root DW plant–1, the free proline contents of leaves, and leaf chlorophyll contents. The use of ‘cash’ also increased the number of fruit plant–1, fruit yield pot–1, and fruit vitamin C contents, although total soluble solids (TSS) contents were not affected. The contents of nitrogen (N), potassium (K), and calcium (Ca), and the Ca:Na ratios of leaf tissues increased with all application rates of ‘cash’. Leaf phosphorus (P) contents showed no response to any applied level of ‘cash’. Leaf sodium (Na) contents declined gradually with an increase in the level of ‘cash’ applied to the soil. We concluded that ‘cash’ has a pronounced positive effect on the growth and fruit yield of tomato plants grown in reclaimed saline soil. ‘Cash’ therefore has the potential to be used as a soil amendment for vegetable crops such as tomato to overcome the adverse effects of salinity in newly-reclaimed soils.