The Influence of Different Crop Mulches on Weed Infestation, Soil Properties and Productivity of Wheat under Conventional and Conservation Production Systems.

Pakistan and other South Asian countries rely on wheat for human nutrition. However, wheat yield is declining in the region due to several biotic and abiotic constraints. Weeds are among the major factors responsible for yield decrease and farmers manage them by intensive tillage practices. Several studies have investigated the impact of various tillage practices on weed management in wheat. However, weed suppression abilities of different mulch types are rarely tested. This three-year (2019-20, 2020-21 and 2021-22) study investigated the impact of different mulch types (prepared from different crops) on weed infestation, soil properties and productivity of wheat under conventional and conservation production systems at three locations (Multan, Hafizabad and Faisalabad) in Punjab, Pakistan. The mulches included in the study were cotton sticks mulch, mungbean straw mulch, sorghum straw mulch, rice straw mulch, sunflower straw mulch, plastic mulch, and no mulch (as control). The production systems opted for wheat cultivation were conventionally tilled wheat (CTW), zero-tilled wheat (ZTW) and zero-tilled wheat sown with happy seeder machine (HSW). The CTW resulted in the lowest soil bulk density and the highest soil porosity after wheat harvest, while ZTW behaved oppositely. Similarly, incorporation of crop mulches resulted in the highest soil porosity and the lowest soil bulk density, while no-mulch incorporation and plastic mulch recorded the highest bulk density and the lowest soil porosity. Regarding mulches by production systems' interaction, CTW with sorghum straw- and plastic mulches recorded the lowest weed density and biomass, while ZTW with no-mulch recorded the highest weed density and biomass at all locations. The CTW with mungbean straw- and plastic mulches resulted in the highest yield due to significant improvement in yield-related traits. However, ZTW with sorghum straw mulch and no-mulch resulted in the lowest wheat yield. Although sorghum straw mulch suppressed weed infestation, it negatively affected wheat growth. Economic analysis revealed that CTW with mungbean straw mulch resulted in the highest gross and net incomes and benefit:cost ratio (BCR), while the ZTW with rice straw- and sorghum straw mulches produced the lowest gross and net incomes and BCR at all locations. Therefore, mungbean straw mulch is a viable option to improve wheat productivity and net economic returns under different agro-climatic conditions of Punjab, Pakistan.

Foliar application of seed water extract of Nigella sativa improved maize growth in cadmium-contaminated soil.

Cadmium (Cd) is a widespread heavy metal, which commonly exert negative impacts on agricultural soils and living organisms. Foliar application of seed water extract of black cumin (Nigella sativa L.) can mitigate the adverse impacts of Cd-toxicity in plants through its rich antioxidants. This study examined the role of seed water extracts of N. sativa (NSE) in mitigating the adverse impacts of Cd-toxicity on maize growth. Two maize genotypes (synthetic 'Neelum' and hybrid 'P1543') were grown under 0, 4, 8 and 12 mg Cd kg-1 soil. The NSE was applied at three different concentrations (i.e., 0, 10 and 20%) as foliar spray at 25 and 45 days after sowing. All Cd concentrations had no effect on germination percentage of both genotypes. Increasing Cd concentration linearly decreased root and allometric attributes, gas exchange traits and relative water contents of hybrid genotype. However, gas exchange traits of synthetic genotype remained unaffected by Cd-toxicity. Overall, hybrid genotype showed better tolerance to Cd-toxicity than synthetic genotype with better germination and allometric attributes and less Cd accumulation. Foliar application of NSE lowered negative effects of Cd-toxicity on all studied traits, except relative water contents. In conclusion, foliar application of NSE seemed a viable option to improve maize growth in Cd-contaminated soil.

Exogenous application of black cumin (Nigella sativa) seed extract improves maize growth under chromium (Cr) stress.

Accumulation of non-essential heavy metals like chromium (Cr) is among major abiotic stresses, which adversely affect crop growth. Hexavalent chromium [Cr(VI)] is the most dangerous form negatively affecting the growth and productivity of crops. This study evaluated the role of black cumin extracts (BCE) in improving growth and productivity of maize genotypes under different concentrations of Cr(VI). Two maize genotypes ("Neelum" and "P1543") were grown under 0, 4, 8 and 12 mg Cr(VI) kg-1 concentrations. The BCE was applied as foliar spray at three concentrations (0, 10 and 20%) at 25 and 45 days after sowing. Increasing Cr(VI) concentration significantly (p < 0.05) reduced seed germination, root and allometric traits, gas exchange attributes and relative water contents of tested genotypes. Hybrid maize genotype better tolerated tested Cr(VI) concentrations than synthetic genotype with lower Cr accumulation and better allometric and gas exchange traits. Exogenous application of 20% BCE proved effective in lowering the adverse effects of Cr(VI) toxicity on maize genotypes. It is concluded that 20% BCE could be used to improve maize performance through better allometric and gas exchange traits under different Cr(VI) concentrations. Nonetheless, actual mechanisms involved in improved Cr(VI)-tolerance of maize with BCE application must be explored. Novelty statement Black cumin has been widely used to reduce Cr toxicity in animals. However, the role of black cumin in reducing Cr toxicity in plants has never been studied. The present study was conducted to infer the role of different concentrations of black cumin extract in improving the growth of synthetic and hybrid maize genotypes under different levels of Cr stress. It is concluded that black cumin extract could be used to lower Cr toxicity in maize grown under Cr-contaminated soils.

Correction: Iron application improves yield, economic returns and grain-Fe concentration of mungbean.

[This corrects the article DOI: 10.1371/journal.pone.0230720.].

Iron application improves yield, economic returns and grain-Fe concentration of mungbean.

Malnutrition is among the biggest threats being faced globally, and Pakistan is among the countries having high malnutrition rate. Pulses grown in Pakistan have lower amounts of micronutrients, especially iron (Fe) in grains compared to developed world. Biofortification, -a process of integrating nutrients into food crops-, provides a sustainable and economic way of increasing minerals/micronutrients' concentration in staple crops. Mungbean fulfills protein needs of large portion of Pakistani population; however, low Fe concentration in grains do not provide sufficient Fe. Therefore, current study was conducted to infer the impact of different Fe levels and application methods on yield, economic returns and grain-Fe concentration of mungbean. Mungbean was sown under four levels of Fe, i.e., 0, 5, 10 and 15 kg Fe ha-1 applied by three methods, i) as basal application (whole at sowing), ii) side dressing (whole at 1st irrigation) and iii) 50% as basal application + 50% side dressing (regarded as split application). Iron levels and application methods significantly influenced the allometry, yield, economic returns and grain-Fe concentration of mungbean. Split application of 15 kg Fe ha-1 had the highest yield, economic returns and grain-Fe concentration compared to the rest of Fe levels and application methods. Moreover, split application of 15 kg Fe ha-1 proved a quick method to improve the grain-Fe concentration and bioavailability, which will ultimately solve the Fe malnutrition problem of mungbean-consuming population in Pakistan. In conclusion, split application of Fe at 15 kg ha-1 seemed a viable technique to enhance yield, economic returns, grain-Fe concentration and bioavailability of mungbean.