PENGARUH PENAMBAHAN KALIUM NITRAT DALAM LARUTAN HARA PADA MEDIA KASCING TERHADAP PERTUMBUHAN SELADA (Lactuca sativa L.)

This research was conducted with the aim to find out the effect of the addition of potassium nitrate in lettuce as a medium and critical level of concentration(electrical conductivity)of nutrient solution. Research is organized in the form of a pot experiment. The experimental design used was Complete RandomizedBlock Design (CRBD)) with three replications. The treatment consists of 12 levels of concentrations or nutrient solution electrical conductivity with the addition of potassium nitrate to lettuce plant. The treatment level of concentrations (conductivity) of nutrient is as follows; L0 = 0.00; L1 = 1.25; L2 = 2.50; L3 = 3.75; L4 = 5.00; L5 = 6.25; L6 = 7.50; L7 = 8.75; L8 = 10.00; L9 = 11.25; L10 = 12.50 and L1 = 13, 75 g 100 L-1 water. Value concentrations of electrical conductivity each nutrient solution concentrations are: L0 = 0.06; L1 = 0.26; L2 = 0.46; L3 = 0.66; L4 = 0.86; L5 = 1.06; L6 = 1.26; L7 = 1,46; L8 = 1.66; L9 = 1,86; L10 = 2.06 and L1 = 2.26. dS m-1. The result of the experiment showed that addition of KNO3 highly significant effect on the increase in fresh weight and dry weight of shoot per plant. Fresh weight and oven-dry weight of shoot per plant was significantly increased in a quadratic with increasing concentrations of KNO3are optimum for growth of plant shoot weight were at 12.23 g in 100/of water on electrical conductivity equivalent to 2.01 dS.m-1. The addition of concentration of KNO3to nutrient solution does not affect on N and other nutrient solution on shoot tissue of lettuce plant but the concentrations of P and K in plant shoot tissue were significantly increased linearly with the provision of KNO3.

Beware of Fixation—It Might Affect Your Experiments

Because of difficulties during the fixation in space and the often reported enhanced expression of stress-related genes in space experiments, we investigated the possible effect of fixation on gene expression. Comparing two fixatives (RNAlater® and 70% ethanol), two-day-old Brassica rapa seedlings were either fixed by gradual exposure or immediate and complete immersion in fixative for two days. Neither fixative yielded high amounts of rRNA; RNAlater® resulted in higher RNA yield in shoot tissue but qPCR data showed higher yield in ethanol-fixed material. qPCR analyses showed strongly enhanced transcripts of stress-related genes, especially in RNAlater®-fixed material. The data suggest that fixation artefacts may be partially responsible for effects commonly attributed to space syndromes.

Ascorbate oxidation activates systemic defence against root-knot nematode Meloidogyne graminicola in rice

Ascorbic acid (AA) is the major antioxidant buffer produced in the shoot tissue of plants. Previous studies on root-knot nematode (RKN; Meloidogyne graminicola)-infected rice (Oryza sativa) plants showed differential expression of AA-recycling genes, although their functional role was unknown. Our results confirmed increased dehydroascorbate (DHA) levels in nematode-induced root galls, while AA mutants were significantly more susceptible to nematode infection. External applications of ascorbate oxidase (AO), DHA, or reduced AA, revealed systemic effects of ascorbate oxidation on rice defence versus RKN, associated with a primed accumulation of H2O2 upon nematode infection. To confirm and further investigate these systemic effects, a transcriptome analysis was done on roots of foliar AO-treated plants, revealing activation of the ethylene (ET) response and jasmonic acid (JA) biosynthesis pathways in roots, which was confirmed by hormone measurements. Activation of these pathways by methyl-JA, or ethephon treatment can complement the susceptibility phenotype of the rice Vitamin C (vtc1) mutant. Experiments on the jasmonate signalling (jar1) mutant or using chemical JA/ET inhibitors confirm that the effects of ascorbate oxidation are dependent on both the JA and ET pathways. Collectively, our data reveal a novel pathway in which ascorbate oxidation induces systemic defence against RKNs.

Evaluating Peat Substrates Amended with Pine Wood Fiber for Nitrogen Immobilization and Effects on Plant Performance with Container-grown Petunia

Pine (Pinus sp.) wood products have potential to immobilize fertilizer nitrogen (N) and influence plant growth when used in soilless substrates for the production of containerized floriculture crops. Peat substrate was amended with (by volume) 30% pine wood fiber (peat:fiber) during a production phase with fertigation and a simulated consumer retail phase with clear-water irrigation using container-grown ‘Supertunia Vista Bubblegum’ petunia (Petunia ×hybrida). The objective was to evaluate substrate effects on substrate and plant tissue nutrient level and plant growth, with an emphasis on evaluating N immobilization from wood product amendments. Substrates consisting of peat amended with hammer-milled pine wood (peat:wood) or coconut (Cocos nucifera) coir (peat:coir) were used for comparison, and a 100% peat substrate (peat) served as a control. In Expt. 1, amending peat with pine wood fiber had no effect on leaf SPAD chlorophyll index, shoot growth, plant height and width, substrate N, or percent shoot tissue N at the end-of-production. In Expt. 2, plants grown in peat:fiber had reduced flower number, plant height and width, and shoot growth compared with plants grown in the 100% peat control. However, petunia grown in peat:fiber substrates maintained dark-green foliage with high leaf SPAD chlorophyll index values (≥44.4) and ≥45 flowers/plant, and therefore were considered marketable plants. During the production phase in both Expts. 1 and 2, N concentrations remained within the target range for petunia in both the shoot tissue and root-zone for all substrates. In addition, there was no statistical evidence of N immobilization for any substrate blend for either of the N drawdown procedures. In both Expts. 1 and 2, root-zone nutrients became depleted during the consumer phase when irrigation was with clear water (no fertilizer), and petunia developed uniform symptoms of leaf chlorosis and N deficiency. Results of this study indicate that peat amended with 30% pine wood fiber, hammer-milled pine wood, and coconut can be used for production of containerized petunia with minimal effects on plant growth or need to adjust the fertilizer program. However, increasing pine wood to >30% of the substrate volume may require growers to increase fertilization and adjust irrigation practices to compensate for greater risk of N immobilization and changes in substrate physical properties.

Veronica becabonga L. as a hyperaccumulatorplant for cadmium

Heavy metal pollution of water is a major environmental problem facing the modem world.The major objective of this research was to evaluate the potential of water-speedwell plant,Veronica becabonga L. to uptake and accumulate heavy metal cadmium under greenhouseconditions, Veronica becabonga L., were cultured in 3% Hoagland's nutrient medium, whichwas supplemented with 0, 25, 50,100, 200, 300 mg/I of Cd(NO3)2 4H2O over one weektreatment period. Plants were harvested at the end of this period and heavy metals from theentire shoot tissue was extracted using the closed Teflon vessel method and metal content inthe extract was estimated using a Flame atomic absorption spectrophotometry. The resultsshowed that the uptake and accumulation of Cd in V becabonga L. showed significantincrease when metal concentration was increased. The highest amount of Cd accumulationwas detected at 100mg/I Cd(NO3)24H2O in the culture solution that was 20660.3 mg/kg DWof shoots. The linear pattern of uptake suggest the involvement of both active and passivetransport mechanisms for Cd uptake, Finally, since the high concentrations cadmiumaccumulation in shoots of plants has far exceeded 0.01% DW V becabonga L. is ahyperaccumulator plant for this metal and has potential for phytoremediation of watercontaminated with cadmium,

Efek Timbal (Pb) Terhadap Pertumbuhan dan Adaptabilitas Acacia mangium Pada Tailing Emas

Gold mining is a human activity with high environmental risk through its tailing, due to the heavy metals content. Lead (Pb) is one of dangerous heavy metals in the world, because its toxicity to organism and environment. Phytoremediation is a method to remove hazard pollutant from environment by using plant. Acacia mangium is fast growing and pioneer tree species which mostly grow on the secondary forest as well as marginal land. Usually, this species is used for revegetation on postmining land. Study on Pb effect to A. mangium is an important issue to support phytoremediation advancement as well as for forest restoration. This study aimed to analyze the effect of Pb with several levels toward the growth and adptability of A. mangium on the gold tailing. The results showed that Pb increment on tailing were significantly effect on the growth and adaptability of the plants. A. mangium showed a well performance even on 900 mg Pb/kg tailing with high tolerance index (TI > 100%). Moreover, this species had ability to accumulate Pb in the root higher than shoot tissue. A. mangium had a good potency as phitoremediant plant, also as revegetation plant on the marginal land, such as on the gold mining tailing. Key words: Acacia mangium, heavy metal, lead, phytoremediation, Pb

Relative Salt Tolerance of Four Herbaceous Perennial Ornamentals

Salt tolerant ornamental plants can be irrigated with alternative water sources that are typically saline as a sustainable practice for urban landscaping, especially in arid and semi-arid regions. However, the salt tolerance of many ornamentals is not known. An eight-week greenhouse experiment was conducted to assess the relative salt tolerance of four perennial ornamentals, ‘Angelina’ (Sedum rupestre), ‘Autumn Joy’ (S. telephium), ‘Blue Spruce’ (S. reflexum), and ‘Blue Daze’ (Evolvulus glomeratus). The plants were grown in pots with potting mix substrate and irrigated with control or saline solutions. The electrical conductivities (EC) of the saline solutions were 5.0 and 10.0 mS/cm. Data collected included relative shoot, root, and total dry weight (DW), visual score, shoot tissue concentrations of Na+, Cl−, K+, and Ca2+, and the K+/Na+ ratio. There were significant differences in treatment and varieties for all response variables, and some interactions were also significant, indicating different responses to salinity for the four varieties. Shoot, root, and total DW decreased with increasing salinity for all varieties. Visual score was highest in Autumn Joy and Blue Spruce when treated with EC5 and EC10 and lowest in Angelina and Blue Daze, the latter of which showed symptoms of moderate foliar damage including leaf necrosis, or “burn”, due to salt stress. The concentrations of Na+ and Cl− in the shoot tissue increased with increasing salinity while K+ and Ca2+ and the K+/Na+ ratio tended to decrease. Of the four varieties of herbaceous perennial ornamentals evaluated in this study, Autumn Joy and Blue Spruce were considered the most relatively salt tolerant while Angelina and Blue Daze were least tolerant.

Biochemical responses of sainfoin shoot and root tissues to drought stress in In vitro Culture

This study was conducted to investigate the biochemical responses of the shoot and root tissues of sainfoin to drought stress under in vitro conditions. Seeds of sainfoin were cultured on MS (Murashige and Skoog) medium with addition of concentrations of PEG-6000 (50, 100, and 150 g/l). Biochemical analyzes (CAT, SOD, GR, and APX enzyme activity; proline, malondialdehyde (MDA) and chlorophyll contents) were carried out on the 35-day-old seedlings. The principal results of the study were that CAT and SOD antioxidant enzymes seemed to play a critical role in oxidative stress in both tissues of sainfoin seedlings. On the other hand, a significant decrease in GR activity and no change in APX activity detected in both tissues under stress. The contents of proline and MDA increased in both tissues while the chlorophyll contents decreased in the shoot tissue. Antioxidant enzyme activities seemed to be more active in the root tissue than the shoot tissue. Accumulation of proline was higher in the root tissue, while the MDA content was higher in the shoot tissue of the seedlings.

Natural abundance of 15N of N derived from the atmosphere by different strains of Bradyrhizobium in symbiosis with soybean plants

ABSTRACT: To quantify the BNF contribution to legumes using the 15N natural abundance technique, it is important to know the abundance of 15N of the plants grown entirely dependent on BNF (value ‘B’). The aim of the study was to determine the 15N natural abundance of N2 fixed by different Bradyrhizobium strains in symbiosis with one soybean cultivar. Treatments consisted of soybean plants cultivated with and without inoculation with ten Bradyrhizobium strains, in five replicates planted in Leonard jars in a sand/vermiculite mixture. Plants were harvested after 46 days. The ‘B’ values of the aerial tissue (‘Bs’) ranged from -2.6 to -3.9 ‰. There was a tendency for the ‘Bs’ values of plants inoculated with strains of B. elkanii to be more negative than plants inoculated with other strains. All ‘B’ values of the whole plant were less than 1 unit of δ15N (‰) different from zero, suggesting that the symbioses have little tendency to show significant isotopic fractionation during N2 fixation, but there is considerable depletion in 15N of the N translocated to the shoot tissue.