Sorghum Allelopathy: Alternative Weed Management Strategy and Its Impact on Mung Bean Productivity and Soil Rhizosphere Properties.

The reduction of herbicide use and herbicide-resistant weeds through allelopathy can be a sustainable strategy to combat the concerns of environmental degradation. Allelopathic crop residues carry great potential both as weed suppressers and soil quality enhancers. The influence of sorghum crop residues and water extracts on the weed population, soil enzyme activities, the microbial community, and mung bean crop productivity was investigated in a two-year experiment at the Student Research Farm, University of Agriculture Faisalabad. The experimental treatments comprised two levels of sorghum water extract (10 and 20 L ha-1) and two residue application rates (4 and 6 t ha-1), and no sorghum water extract and residues were used as the control. The results indicated that the incorporation of sorghum water extract and residue resulted in significant changes in weed dynamics and the soil quality indices. Significant reduction in weed density (62%) and in the dry weight of weeds (65%) was observed in T5. After the harvest, better soil quality indices in terms of the microbial population (72-90%) and microbial activity (32-50%) were observed in the rhizosphere (0-15 cm) by the same treatment. After cropping, improved soil properties in terms of available potassium, available phosphorus soil organic matter, and total nitrogen were higher after the treatment of residue was incorporated, i.e., 52-65%, 29-45%, 62-84%, and 59-91%, respectively. In the case of soil enzymes, alkaline phosphatase and dehydrogenase levels in the soil were 35-41% and 52-77% higher, respectively. However, residue incorporation at 6 t ha-1 had the greatest effect in improving the soil quality indices, mung bean productivity, and reduction of weed density. In conclusion, the incorporation of 6 t ha-1 sorghum residues may be opted to improve soil quality indices, suppress weeds, harvest a better seed yield (37%), and achieve higher profitability (306 $ ha-1) by weed suppression, yield, and rhizospheric properties of spring-planted mung beans. This strategy can provide a probable substitute for instigating sustainable weed control and significant improvement of soil properties in the mung bean crop, which can be a part of eco-friendly and sustainable agriculture.

First Report of Aspergillus niger causing Black rot of Grapes in Pakistan.

In June 2015 & 2016, a postharvest survey of table grapes (Vitis vinifera) cv. King's Ruby, was carried out in five different commercial fruit markets of Rawalpindi (33°38'19.2″N, 73°01'45.0″E) district, Punjab Province. Symptoms appeared as brownish lesions with black sporulation on grapes berries. The incidence of these symptoms on bunches ranged from 12 to 17% at all sites. Symptomatic tissue pieces were surface-sterilized with 0.1% sodium hypochlorite (NaOCl) for 30 seconds, rinsed three times with sterile distilled water, dried on filter paper for 45 seconds, and incubated on potato dextrose agar (PDA) at 25°C. After 3 days, dark brown to black mycelium were formed on PDA media. A total of 24 isolates were examined morphologically. The apex of the conidiophore was observed to be radiate. Vesicles were found to be spherical and covered with irregular metulae and phialides. Conidia were globose or subglobose measured (3.14 µm ± 2.24 in averaged diameter: n=50), dark brown to black, with roughened cell walls. The conidiophores were also smooth-walled, hyaline, and became melanized toward the vesicle. These characteristics of the fungus were similar to those described for Aspergillus niger van Tiegh (de Hoog et al. 2000). For molecular identification, the internal transcribed spacer (ITS) region, beta-tubulin (Bt) gene and partial RNA polymerase II largest subunit (RPB2) gene of representative isolate (Asp.n02) was amplified using primers ITS1/ITS4, BT2a/BT2b and RPB2-6F/RPB2-7R respectively (White et al., 1990; Glass & Donaldson, 1995; Liu et al. 1999). Sequences were deposited in GenBank (ITS, MN658871; Bt2, MT117924; and RPB2, MT318289). Based on BLAST analysis, sequences of the ITS region, Bt2 genes, and RPB2 gene showed 99 to 100% similarity of isolate Asp.n02 to Aspergillus niger (Accession Nos. MK307680.1, MN195121.1, MF078661.1 for ITS gene, MN567299.1, MK451029.1, MK451020.1 for Bt2 gene, and MK450788.1, MK450790.1 for RPB2 gene). To complete Koch's postulates, 10-µl aliquots of spore suspensions (106 spores/ml) of isolate: Asp.n 02 was pipetted onto three non-wounded and four wounded (5 mm diam) asymptomatic grape berries cv. King's Ruby (seven berries per isolate), Sterile distilled water was applied to asymptomatic berries similaries to serve as a negative control (Ghuffar et al. 2018; Jayawardena et al. 2018). Berries were incubated at 25 ± 2°C in sterile moisture chambers, and the experiment was conducted twice. Brownish lesions leading to black sporulation similar to the original symptoms were observed on both wounded and non-wounded inoculated berries after 3 days, whereas no symptoms were recorded on the negative control. The morphology of the fungus that was re-isolated from each of the inoculated berries was identical to that of the original cultures. Aspergillus niger was reported previously in Europe and Israel causing mycotoxin (Ochratoxin A) OTA production on Table grapes (Bau et al. 2006). To our knowledge, this is the first report of Aspergillus niger causing black rot of grapes in Pakistan. This finding will help to plan effective disease management strategies against the black rot of grapes in Pakistan.

Conferring drought-tolerant wheat genotypes through morpho-physiological and chlorophyll indices at seedling stage.

The decrease in water resources due to the excessive use of water for irrigation purpose and climatic changes represents a serious world-wide threat to food security. In this regards, 50 wheat accessions were analyzed, using completely random factorial design at the seedlings stage under normal and drought stress conditions. Significant variation was detected among all accessions under both conditions. All characters studied showed variations in the mean values in water deficit environments in studied gemplasm at seedling stage. As seedling fresh weight, dry weight, relative water content, cell membrane thermo-stability, chlorophyll a & b were positively associated among themselves under drought conditions which showed the significance of these attribute for water deficit areas in future wheat breeding programs. Based on their performance, five accessions namely Aas-11, Chakwal-86, Pasban-90, Chakwal-97 and Kohistan-97 were selected as drought tolerant and three accessions namely Mairaj-08, Lasani-2008 and Gomal-2008 were selected as drought susceptible genotypes. The choice of wheat accessions based on the characteristics of the seedlings is informal, low-priced and less hassle. Likewise, the seedlings attributes exhibit moderate to high variation with an additive genetics effects on the environments. Best performance accessions under water deficit environment will be beneficial in future wheat breeding schemes and early screening for the attributes suggested in current experiment will be useful for producing best-yielded and drought-tolerance wheat genotypes to sustainable food security.

Assessment of grain yield indices in response to drought stress in wheat (Triticum aestivum L.).

Drought stress constricts crop production in the world. Increasing human population and predicted temperature increase owing to global warming will lead ruthless problems for agricultural production in near future. Hence, use of high yielding genotypes having drought tolerance and scrutinize of drought sensitive local cultivars for making them tolerant may be the proficient approaches to cope its detrimental outcomes. The current study was executed during 20015-2016 and 2016-2017 in field using randomized complete block design under factorial arrangements on 50 wheat genotypes for exploring their sensitivity and tolerance against drought. Some of the attributes of grain yield and drought tolerance indices were recorded. Grain yield showed negative correlations with tolerance index (TOL), drought index (DI) and stress susceptibility index (SSI) while positive correlation with mean productivity (MP) and geometric mean productivity (GMP) under drought condition. These findings depicted that tolerant genotypes could be chosen by high MP and GMP values and low SSI and TOL values. Based on the results, genotypes GA-02, Faisalabad-83, 9444, Sehar-06, Pirsabak-04 and Kohistan-97 were more tolerant and recognized as suitable for both normal and drought conditions. Genotypes of Chenab-00, Kohsar-95, Parwaz-94 and Kohenoor-83 confirmed more sensitive due to high grain yield loss under drought stress.