No abstract

No abstract

Background: Low soil temperature in spring is a major constraint for cultivation of tropical crops in temperate climates, associated with impaired seedling development, inhibition of root growth and root activity. In this study, potential cold-stress protectants, such as supplemented micronutrients (Zn, Mn), seaweed extracts, and rhizobacteria with plant growth-promoting potential (PGPRs) were tested in order to improve the tolerance of maize to low root zone temperatures (RZT) during early growth.Methods: Maize (v. Colisee) was cultivated in a root cooling system for adjustment of the RZT. In three independent experiments, after germination at 20 °C, the cold-stress phase (12-14 °C) started at 14 days after sowing to simulate a cold period in spring. Micronutrients, seaweed extracts, and PGPRs were supplied by fertigation (experiment 1), fertigation and seed dressing (experiment 2), and nutrient seed priming (experiment 3). At the end of the experiments, scoring of oxidative leaf damage, biomass production, chlorophyll status (SPAD), root length density, superoxide dismutase activities in leaf and root tissues, and the shoot mineral-nutritional status were determined. Results:Positive effects on plant growth and particularly on root development at low RZT were detected exclusively for seaweed extracts with high Zn/Mn contents and similar growth promotions were induced by Zn and Mn application in comparable amounts. This finding suggests that the selected seaweed extracts were mainly acting via improved Zn and Mn supply to the plants. It was essential that the cold-stress protectants were present during seed imbibition. The beneficial effect of Zn/Mn treatments and sea weed extracts was associated with increased superoxide dismutase activity in the root and leaf tissue, with key functions in antioxidative stress defense, depending on Zn, Mn, Cu, and Fe as enzymatic co-factors. Accordingly, leaf damage, shoot and root growth inhibition in cold-stressed plants was associated with a low Zn-nutritional status, mitigated by application of the cold-stress protectants. Conclusions:Since micronutrients are effective already at low concentrations, starter applications of Zn/Mn or the respective seaweed extracts may offer an economic option for cold-stress prophylaxis in crops.

No abstract

Continuous cropping of rice (Oryza sativa L.) and wheat (Triticum aestivum L.) deplete soil fertility and reduce crop productivity as well as zinc (Zn) concentrations in rice grains and straw. Low Zn concentrations in rice grains have a negative impact on human health, while low Zn concertation in rice straw creates a nutritional problem for animals. The current high yielding rice varieties and hybrids remove large quantities of Zn from the soils, lowering the residual concentrations of soil Zn for the subsequent crop (e.g., wheat). Field experiments were conducted on farmers field in Malakand with the objective to evaluate the impact of various combinations of phosphorus (0, 40, 80, and 120 kg ha−1) and Zn levels (0, 5, 10, and 15 kg ha−1) on biofortification of Zn in grains and straw of rice genotypes [fine (Bamati-385) vs. coarse (Fakhre-e-Malakand and Pukhraj)]. The results revealed that Zn biofortification in rice genotypes increased with the integrated use of both nutrients (P + Zn) when applied at higher rates (80 and 120 kg P ha−1, and 10 and 15 kg Zn ha−1, respectively). The biofortification of Zn in both grains and straw was higher in the coarse than fine rice genotypes (Pukhraj > Fakhre-e-Malakand > Basmati-385). It was concluded from this study that the application of higher P and Zn levels increased Zn contents in rice parts (grains and straw) under the rice-wheat system. We also concluded from this study that Zn concentrations in rice grains and straw are influenced by plant genetic factors and Zn management practices.

Laboratory experiments were conducted to examine the efficacy of fertilizer priming on seed germination behavior and vigor of two maize cultivars "Azam and Phari" at Agronomy Research Laboratory, University of Agriculture, Peshawar-Pakistan during 2015. Studied treatments include hydropriming (distilled water) and osmopriming with Calcium Ammonium Nitrate (CAN) at 0.5% for 24 hours. Non primed seed were used as control. Data were recorded on germination and vigor parameters according to standard procedures. Results showed that both hydro and osmo-priming significantly improved germination %, mean germination time, germination index, plumule and radical length, seedling fresh and dry weight of both cultivars as compared to control treatment. Cultivar Azam performed better in all germination and vigor attributes than Phari. It was concluded that both hydro and osmopriming with Calcium Ammonium Nitrate (CAN) at 0.5% for 24 hours are practical approaches for improving growth and vigor of maize crop under harsh environment.

ABSTRACT. The objective of this study was to assess the comparative efficiency of different priming techniques on germination and early seedling growth of maize cultivars. Laboratory experiments were conducted to examine the efficacy of different seed invigoration treatments on seed germination and vigor traits of three maize hybrids, Pioneer 3025, Pioneer 70 and Baber at Agronomy research laboratory, University of Agriculture, Peshawar, Pakistan. The experiment was laid in completely randomized design (CRD) and was replicated thrice.The treatments included control treatment (T 1 ) unsoaked/dry seed, (T 2 ) hydropriming with distilled water for 24 hrs, (T 3 ) halo priming treatments with NaCl (3% solution) for 24 hrs, (T 4 ) osmopriming with PEG-6000 for 24 hrs and (T 5 ), hormonal priming with GA 3 for 24 hrs. The results showed that seed invigoration treatment with gibberellic acid (GA 3 ) PEG-6000 and hydropriming with distilled water for 24 hrs gave higher germination, decreased days to 50% germination, increased shoot length, root length, seedling fresh and dry weight, as compared to halo priming with NaCl and control treatment. It is concluded that seed invigoration with GA 3 , osmopriming with PEG-6000 and hydropriming with distilled water for 24 hrs serve as an appropriate treatment for accelerating the emergence and growth parameters of maize hybrid. Pioneer 3025 showed its superiority over other cultivars in all the studied parameters.

Low temperature during germination hinders germination speed and early seedling development. Zn seed priming is a useful and cost-effective tool to improve germination rate and resistance to low temperature stress during germination and early seedling development. Spinach was tested to improve germination and seedling development with Zn seed priming under low temperature stress conditions. Zn priming increased seed Zn concentration up to 48 times. The multispectral imaging technique with VideometerLab was used as a non-destructive method to differentiate unprimed, water- and Zn-primed spinach seeds successfully. Localization of Zn in the seeds was studied using the 1,5-diphenyl thiocarbazone (DTZ) dying technique. Active translocation of primed Zn in the roots of young seedlings was detected with laser confocal microscopy. Zn priming of spinach seeds at 6 mM Zn showed a significant increase in germination rate and total germination under low temperature at 8 °C.