Navegando por Autor "Fiaz, Muhammad"

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Impact of drought on assimilates partitioning associated fruiting physiognomies and yield quality attributes of desert grown cotton
(Acta Physiologiae Plantarum, 2018-03-19) Fiaz, Muhammad; Shareef, Muhammad; Gu, Dongwei; Zeng, Fanjiang; Ahmed, Zeeshan; Waqas, Muhammad; Zhang, Bo; Iqbal, Hassan
Deficit irrigation has great significance for sustainable cultivation of cotton in water scarce arid regions, but this technique creates drought situation that induces stress adaptive changes in cotton plants due to indeterminate growth habit. In the present experiment, the impact of drought stress on assimilates partitioning associated vegetative and reproductive development, and yield quality attributes of cotton were examined under desert conditions. Four levels of drip irrigation including 100, 80, 60, and 40% replenishment of depleted water from field capacity were applied to develop drought stress regimes during two growing seasons (2015 and 2016). Results revealed that under limited water supplies, plant’s preference for allocation of photo-assimilates was roots > leaves > fruits that substantially increased root–shoot ratio and hampered reproductive growth. Consequently, boll density (m−2), fresh boll weight and lint yield (kg ha−1) were significantly reduced. An obvious change in partitioning of assimilates inside stressed bolls was observed that indicated relatively more accumulation in seeds than fiber, thus reducing the fiber quality. In addition, decreased starch, oil, and protein contents in seeds of stressed plants markedly reduced 100 seeds weight and also the vigor. Later, seed quality confirmatory tests of subsequent years (2016 and 2017) showed significant reduction in emergence counts (m−2) and seedling biomasses of seeds harvested from deficit drip irrigated cotton. These results suggest that deficit irrigation could necessarily be an appropriate yield optimization and water saving technique for cotton in desert environment but, for the best quality fiber and cottonseeds, full irrigation should be preferred.
Squamocin induce histological and ultrastructural changes in the midgut cells of Anticarsia gemmatalis (Lepidoptera: Noctuidae)
(Ecotoxicology and Environmental Safety, 2018-07-30) Fiaz, Muhammad; Martínez, Luis Carlos; Costa, Marilza da Silva; Cossolin, Jamile Fernanda Silva; Plata-Rueda, Angelica; Gonçalves, Wagner Gonzaga; Sant’Ana, Antônio Euzébio Goulart; Zanuncio, José Cola; Serrão, José Eduardo
Annonaceous acetogenins (Annona squamosa Linnaeus) comprises of a series of natural products which are extracted from Annonaceae species, squamocin proved to be highly efficient among those agents. Squamocin is mostly referred as a lethal agent for midgut cells of different insects, with toxic effects when tested against larva of some insects. In present study, LC50 and LC90 of squamocin for A. gemmatalis Hübner (Lepidoptera: Noctuidae) were calculated using probit analysis. Morphological changes in midgut cells were analyzed under light, fluorescence and transmission electron microscopes when larvae were treated with LC50 and LC90 of squamocin for 24, 48 and 72 h. Results revealed that the maximum damage to midgut cells was found under LC90 where it showed digestive cells with enlarged basal labyrinth, highly vacuolated cytoplasm, damaged apical surface, cell protrusions to the gut lumen, autophagy and cell death. The midgut goblet cells showed a strong disorganization of their microvilli. Likewise, in insects treated with squamocin, mitochondria were not marked with Mitotracker fluorescent probe, suggesting some molecular damage in these organelles, which was reinforced by decrease in the respiration rate in these insects. These results demonstrate that squamocin has potential to induce enough morphological changes in midgut through epithelial cell damage in A. gemmatalis.
Toxicological and morphological effects of squamocin and tebufenozide on Anticarsia gemmatalis (Lepidoptera: Noctuidae) larvae
(Universidade Federal de Viçosa, 2019-02-19) Fiaz, Muhammad; Serrão, José Eduardo; http://lattes.cnpq.br/7169797411388346
Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) is the main defoliating pest of soybean (Glycine max L. Merrill, FaLO LOURENCO DA SILVAbaceae) in Brazil. There are a variety of plant products and pt-ensynthetic insecticides used to control A. gemmatalis. The larval midgut is reported to be the 'front line' in creation of local immune defense and detoxification of xenobiotic compounds. These characteristics make the midgut cells to be the most affected by those xenobiotics. Squamocin from Annona mucosa and tebufenozide were evaluated to test their toxicity and their ultrastructural effects in midgut cells of A. gemmatalis. Toxicological results showed that A. gemmatalis was susceptible to both squamocin and tebufenozide. Larvae exposed to tebufenozide compromised larval fitness and its survivorship. LC50 and LC90 of squamocin and tebufenozide against A. gemmatalis were 37.14 mg/L-1, 83.14 mg/L-1 and 3.86 mg/L-1, 12.16 mg/L-1, respectively. Squamocin and tebufenozide intake caused deformities in epithelial cells. Squamocin damage to midgut cells include enlarged basal labyrinth, highly vacuolated cytoplasm, damaged apical surface, release of cell protrusions to the gut lumen, autophagy and cell death. Ingestion of tebufenozide caused damage to striated border with release of protrusions to the midgut lumen, damaged nuclear membrane and nucleus with condensed chromatin and increase autophagic vacuolization. Both, squamocin and tebufenozide, damaged mitochondria and compromised respiration rate, while in case of tebufenozide, severe damage resulted in to modification of mitochondria into nanotunnels along with compromising respiration rate. Squamocin and tebufenozide are lethal to larvae, they compromised its fitness and induced severe morphological changes in midgut cells empowering control program against A. gemmatalis.
Toxicological and morphological effects of tebufenozide on Anticarsia gemmatalis (Lepidoptera: Noctuidae) larvae
(Chemosphere, 2018-12) Fiaz, Muhammad; Martínez, Luis Carlos; Plata-Rueda, Angelica; Gonçalves, Wagner Gonzaga; Shareef, Muhammad; Zanuncio, José Cola; Serrão, José Eduardo
The velvetbean caterpillar, Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae), is an important soybean pest in the Americas. Tebufenozide, a novel nonsteroidal ecdysone agonist is used to control this pest. Bioassays were conducted to assess tebufenozide toxicity and their ultrastructural effects on midgut of A. gemmatalis. The toxicity, survivorship, behavior response, and respiration rate for A. gemmatalis larvae after exposure to tebufenozide were evaluated. Also, A. gemmatalis larvae were treated with LC50 obtained from tebufenozide and changes were observed on their midgut cells after 24, 48 and 96 h. Tebufenozide was toxic to A. gemmatalis (LC50 = 3.86 mg mL−1 and LC90 = 12.16 mg mL−1) and survivorship was 95% for adults that had not been exposed to tebufenozide, decreasing to 52% with LC50 and 27% with LC90 estimated value. Damage to midgut cells was increased with exposure time. These cells show damaged striated border with release of protrusions to the midgut lumen, damaged nuclear membrane and nucleus with condensed chromatin and increase in amount of autophagic vacuoles. Mitochondria were modified into nanotunnels which might be an evidence that tebufenozide induces damage to cells, resulting in cell death, proved by immunofluorescence analyses. This insecticide also caused paralysis movement with change in homeostasis and compromised larval respiration. Thus, sublethal exposure to tebufenozide is sufficient to disturb the ultrastructure of A. gemmatalis midgut, which might compromise insect fitness, confirming tebufenozide a possible controlling insecticide.