New alkamides from maca (Lepidium meyenii)

Maca (Lepidium meyenii) has been used as a food in Peru for thousands of years. More recently a wide array of commercial maca products have gained popularity as dietary supplements, with claims of anabolic and aphrodisiac effects, although the biologically active principles are not fully known. In an earlier chemical investigation, two new alkamides and a novel fatty acid, as well as the N-hydroxypyridine derivative, macaridine, were isolated from L. meyenii. Further examination has led to the isolation of five additional new alkamides, namely, N-benzyl-9-oxo-12Z-octadecenamide (1), N-benzyl-9-oxo-12Z,15Z-octadecadienamide (2), N-benzyl-13-oxo-9E,11E-octadecadienamide (3), N-benzyl-15Z-tetracosenamide (4), and N-(m-methoxybenzyl)hexadecanamide (5). Their structures were established by spectrometric and spectroscopic methods including ESI-HRMS, EI-MS, (1)H, (13)C, and 2D NMR, as well as (1)H-(15)N 2D HMBC experiments. In addition, the identity of N-benzyl-15Z-tetracosenamide (4) was confirmed by synthesis. These compounds have been found from only L. meyenii and could be used as markers for authentication and standardization.     

Effect of Water Quality Parameters on the Migration of Vinyl Chloride Monomer from Unplasticized PVC Pipes

The migration of vinyl chloride monomer (VCM) from unplasticizedpolyvinyl chloride (uPVC) pipes was investigated using locallymanufactured pipes. Specimens of 33 cm long were used throughoutthe research. The investigation was carried out under differentconditions of water temperature, pH and total dissolved solidsconcentration and at different durations of exposure. The VCMconcentration in the water was evaluated using the gaschromotography (GC)/head-space technique. A VCM concentration ofmore than 2.5 ppb was detected after 30 days of exposure at45 °C. The initial VCM concentration in the uPVC pipewas predicted using equations derived from Fick's first law ofdiffusion. Water tenperature did not affect the migration ofVCM, unless it was raised to high values (i.e. 45 °C).Total dissolved solids (TDS) and pH of water were found toaffect the release of VCM from uPVC pipes. Diffusion rate of VCMwas predicted as a function of pH or TDS values.     

Accumulation and distribution of Zn and Mn in soybean seeds after nutrient seed priming and its contribution to plant growth under Zn- and Mn-deficient conditions

Nutrient seed priming is a strategy to increase the seed reserves of mineral nutrients as primary source for mineral nutrition during seedling development and early growth. The present study investigates the effects of zinc (Zn) and manganese (Mn) seed priming on growth and nutritional status of soybean under conditions of Zn and Mn limitation. Nutrient seed priming increased the natural seed reserves for Zn by, approximately, sixfold and by fivefold for Mn; however, 40–60% of the primed nutrients were adsorbed to the seed coat. Zinc seed priming was able to maintain plant growth for 5 weeks in the same way as Zn supply via the nutrient solution. It is concluded that nutrient seed priming offers perspectives to improve seed quality of soybean for early seedling development under limited nutrient supply or availability and needs further investigation on performance under various stress conditions.     

Complexing of lead by DTPA in calcareous soils

Ten agricultural soils were spiked with 100 μg of Cu, Zn, and Pb g^?1 of soil. The complexation of Pb by 10^?4 M DTPA was determined after 60 days of metal equilibrium. A theoretical stability model of Fe, Mn, Cu, Zn, Ca, and Pb, between pH 1 and 10 was developed. It showed that CuL^3? (55.4 to 63%), CuHL^2? (0.1 to 9.4%), PbL^3? (29.1 to 33.3%), PbHL^2? (0.01 to 2.5%) and MnL^3? (2.8 to 3.2%) as the predominant species between pH 6 and 9. Other species like CaL^3?, CaHL^2?, FeL^2?, FeHL^?, FeL^3?, FeHL^2?, ZnL^3?, ZnHL^2? and MnHL^2? were less than 0.1% between pH 6 and 9. In the experimental soils, DTPA-Pb complexes accounted for 12.3 to 21.2% of metal complexed after 3 days of DTPA equilibriation. DTPA-Cu complexes were the major complexed species in the soils ranging between 72.5 and 82.2% after 3 days equilibriation with 10^?4 M DTPA. The proportion of Zn complexed by DTPA (3.8 to 10.1%) was much greater than predicted by the theoretical model. On the contrary, Mn was not complexed in appreciable amounts by DTPA.     

Zinc-Induced Changes in Growth Characters,Foliar Properties,and Zn-Accumulation Capacity of Pigeon Pea at Different Stages of Plant Growth

Application of zinc (Zn) [50, 100, 200, 300, and 400 μ g zinc sulfate (ZnSO₄)/g of soil] reduced the foliage and the total growth of pigeon pea [Cajanus cajan (Linn.) Huth]. The root-shoot length ratio, varying little with age, was relatively low in the treated plants. Decrease in dry weights of stem and root was more pronounced in the late stages of plant development. The root-shoot dry weight ratio, maximum in the flowering stage, was lower in treated plants than in the control. Number of pods per plant declined, showing a positive correlation with Zn concentration. Net photosynthetic rate, declining with plant age, was significantly low in the treated plants. Density and size of stomata and trichomes, stomatal conductance, intercellular carbon dioxide concentration, quantity of green pigments, nitrate reductase activity, and the nitrate and protein contents in the leaves also declined significantly. Proportion of vascular tissues both in stems and roots increased with plant age with a concomitant reduction of pith and cortex. Under zinc stress, the relative proportion of tissues varied inconsistently. Dimensions of vessel elements and fibers in stems and roots, increasing with the plant age, were always smaller in the treated plants. The vulnerability factor and mesomorphic ratio of treated plants declined, suggesting induction of water stress due to zinc treatments. Accumulation of Zn^{2 +} in different plant parts was considerably high at each developmental stage of the treated plants, and showed a positive correlation with Zn in the soil.     

Use of optical spectrograpiuc 15N-analyses to trace nitrogen applied at tile heading stage of rice

In the recent decades experimental work has led to the accumulation of vast quantities of valuable data on mineral nutrition of plants through the use of isotopic tracers. However, only limited research has been done with nitrogen presumably because of the high costs of instrumentation and isotopes. A few Investlgatlons on the distribution and accumulation of nitrogen have been reported using mass spectrographic method. For example, Ozaki et al. (1) observed a larger distribution of ammonical nitrogen administered before heading, Into ears, culms, and boot leaves in contrast with other plant parts. They further noted that 35% of the nitrogen applied after heading was found in the ears (2).     

The uptake,distribution, and accumulation of 15N-labelled ammonium and nitrate nitrogen top-dressed at different growth stages of rice

A pot experiment with soil culture was carried out to trace ¹⁵N-labelled nitrogen top-dressed at different growth stages of rice. The study involves the use of a modified vacuum system for determining total nitrogen by gu volumetric measurement, and the N₂ gas sampled in the discharge tube was analysed for nitrogen-15 by the optical spectrographic technique.

The plants took up more nitrogen from (¹⁵NH₄)₂SO₄ than from Na¹⁵NO₃, irrespective of the stage of dressing, and the uptake of both forms was much higher when the planta were top-dressed at the young panicle formation stage as compared with the later dressings. At full maturity the plants had the highest accumulation of labelled nitrogen from both ammonium and nitrate sources when they are top-dressed at the young panicle formation stage. More than 80% ot the labelled nitrogen taken up by the plants waa distributed in the brown rice and this trend was more remarkable when top-dressing was carried out at the milk stage. The distribution patterns of ammonium and nitrate nitrogen were similar in brown rice but differed in leaves and stem.

Nitrogen transported from other parts to the panicle was utilized for the formation ot the husk until the booting stage, and then for brown rice development. With the completeness of husk formation, at the milk stage, nitrogen transported to the grain might have been utilized for brown rice development more rapidly. In the brown rice, nitrogen from ammonium was translocated maximally to the inner part of the endosperm from dressing at the booting stage, and to the embryo from that at the milk stage, whereas that from nitrate was translocated maximally to the embryo from the dressings at both stages.     

Alleviation of manganese toxicity and manganese-induced iron deficiency in barley by additional potassium supply in nutrient solution

Barley plants were grown hydroponically at two levels of K (3.0 and 30 mm) and Fe (1.0 and 10 μm) in the presence of excess Mn (25 μm) for 14 d in a phytotron. Plants grown under adequate K level (3.0 mm) were characterized by brown spots on old leaves, desiccation of old leaves, interveinal chlorosis on young leaves, browning of roots, and release of phytosiderophores (PS) from roots. These symptoms were more pronounced in the plants grown under suboptimal Fe level (1.0 p,M) than in the plants grown under adequate Fe level (10 μm). Plants grown in 10 μm Fe with additional K (30 mm) produced a larger amount of dry matter and released less PS than the plants grown under adequate K level (3.0 mm), and did not show leaf injury symptoms and root browning. On the other hand, the additional K supply in the presence of 1.0 μM Fe decreased the severity of brown spots, prevented leaf desiccation, and increased the leaf chlorophyll content, which was not sufficient for the regreening of chlorotic leaves. These results suggested that the additional K alleviated the symptoms of Mn toxicity depending on the Fe concentration in the nutrient solution. The concentration (per g dry matter) and accumulation (per plant) of Mn in shoots and roots of plants grown in 10 μm Fe and 30 mm K were much lower than those of the plants grown in 10 μm Fe and 3.0 mm K, indicating that additional K repressed the absorption of Mn. The concentration and accumulation of Fe in the shoots and roots of the plants grown in 10 μm Fe and 30 mm K were higher than those of the plants grown in 10 μm Fe and 3.0 mm K, indicating that the additional K increased the absorption of Fe under excess Mn level in the nutrient solution. The release of PS, chlorophyll content, and shoot Fe concentration were closely correlated.     

Potato tuber yield and quality in response to different nitrogen fertilizer application rates under two split doses in an irrigated sandy loam soil

Abstract

Management strategies to minimize nitrogen (N) losses to the atmosphere and water bodies from potato production fields while maintaining tuber yields and quality relies on good N management. A 2-year (2016–17 and 2017–18) field trial with ‘Symphonia’ potato was completed on a sandy loam soil irrigated with flood irrigation in Punjab, Pakistan to investigate the effect of N fertilizer rate on vegetative, yield and tuber quality parameters. The N fertilizer treatments comprising six N rates from 0 to 300?kg ha^?1 were applied at 50?kg N increments. Number of stems and tubers plant^?1 showed a quadratic response while other parameters revealed cubic trends in response to N fertilizer rates. Applying more than 250?kg ha^?1 of N fertilizer did not increase vegetative growth and yield. In conclusion, the optimal N-application rate of 250?Kg ha^?1 has great potential to improve yield and quality of potato in the sub-tropical region of Punjab, Pakistan. These findings, besides improving productivity can minimize the risk of N fertilizer loss to the atmosphere.     

Effects of inoculation with stress-adapted arbuscular mycorrhizal fungus Glomus deserticola on growth of Solanum melogena L. and Sorghum sudanese Staph. seedlings under salinity and heavy metal stress conditions

The beneficial effects of a Glomus deserticola strain isolated from the rhizosphere of grasses (belonging to Poaceae family) growing along the industrial waste from a distillery were investigated under stress conditions. The study was conducted to assess the efficacy of the arbuscular mycorrhizal (AM) fungal ecotype in salinity and heavy metal (HM) tolerance of eggplant (Solanum melongena L.) in soils amended with various stress levels of NaCl, zinc and cadmium. Mycorrhizal (M) seedlings produced a significantly (p < 0.05) greater growth response and were more tolerant to salt and HM stresses than nonmycorrhizal (NM) seedlings in all treatments. The HM contents in the plant tissues were significantly higher in M than NM eggplants. Furthermore, when the efficacy was compared with other AM isolates in HM-polluted soils with Sudan grass (Sorghum sudanese Staph.) as a test plant, the AM ecotype responded best to these soils, as evident from the significantly greater growth response and its aggressiveness in colonizing roots in all soil types tested. These results suggest that this G. deserticola ecotype can be used as an effective tool to alleviate the adverse effects of excessive salinity and HM toxicity on plant growth. Finally, the isolate may have potential in the bioremediation of polluted soils.