Phenotypic stability under stress environment facilitate the fitness of genotype and opens new horizons to explore the cryptic genetic variation. Variation in tolerance to drought stress, a major grain yield constraint to global maize production, was identified, at the phenotypic and genotypic level. Here we found a prominent hybrid H9 that showed fitness over four growing seasons for grain yield under water stress conditions. Genotypic and phenotypic correlation of yield attributing traits over four seasons demonstrated that cobs per plant, 100 seed weight, number of grains rows per cob, total dry matter, cob diameter had positive association (r2 = 0.3-0.9) to grain yield. The perturbation was found for chlorophyll content as it showed moderate to strong association (P < 0.01) over four seasons, might be due to environment or genotype dependent. Highest heritability (95%) and genetic advance (79%) for grain yield was found in H9 over four consecutive crop growing seasons. Combined analysis over four seasons showed that studied variables together explained 85 % of total variation in dependent structure (grain yield) obtained by principle component analysis. This significant finding is the best example of phenotypic stability of grain yield in H9 and made it best fitted for grain yield under drought stress scenario. Detailed genetic analysis of H9 will help us to identify significant loci and alleles that made H9 the best fitted and it could serve as a potential source to generate novel transgressive levels of tolerance for drought stress in arid/semiarid regions.

This study was carried out to evaluate F1 single cross-maize hybrids in four crop growing seasons (2010–2012). Morphological traits and physiological parameters of twelve maize hybrids were evaluated (i) to construct seed yield equation and (ii) to determine grain yield attributing traits of well-performing maize genotype using a previously unexplored method of two-way hierarchical clustering. In seed yield predicting equation photosynthetic rate contributed the highest variation (46%). Principal component analysis data showed that investigated traits contributed up to 90.55% variation in dependent structure. From factor analysis, we found that factor 1 contributed 49.6% variation (P<0.05) with primary important traits (i.e., number of leaves per plant, plant height, stem diameter, fresh leaves weight, leaf area, stomata conductance, substomata CO₂absorption rate, and photosynthetic rate). The results of two-way hierarchical clustering demonstrated that Cluster III had outperforming genotype H₁₂(Sultan × Soneri) along with its most closely related traits (photosynthetic rate, stomata conductance, substomata CO₂absorption rate, chlorophyll contents, leaf area, and fresh stem weight). Our data shows that H₁₂(Sultan × Soneri) possessed the highest grain yield per plant under environmentally stress conditions, which are most likely to exist in arid and semiarid climatic conditions, such as in Pakistan.

Chromium (Cr)-contaminated tannery wastewater is a major environmental concern, especially in developing countries, such as Pakistan, due to its use for crop irrigation, resulting in food-chain contamination and health issues. In this study, we explored the distribution, speciation, hydrogeochemical behavior and environmental risks of Cr in tannery wastewater collected from various tanneries of Kasur district in Punjab, Pakistan. Tannery wastewater samples were taken during the summer (TWW-summer; n = 82) and winter (TWW-winter; n = 82) seasons. The results showed that high Cr concentration was observed in TWW-winter (mean: 49 ± 32 mg L⁻¹) compared to TWW-summer (mean: 15 ± 21 mg L⁻¹). In TWW-summer and TWW-winter samples, the Cr concentration exceeded the National Environmental Quality Standard (1 mg L⁻¹), with the total Cr ranging from 2.8 to 125 mg L⁻¹. Hexavalent Cr (Cr(VI)) and trivalent Cr (Cr(III)) concentrations spanned 2.7 to 2.9 and 12.4 to 46 mg L⁻¹, respectively. The Piper plot showed that hydrogeochemistry of wastewater was dominated by Ca-Mg-SO₄ and Ca-Mg-Cl type water, and geochemical modeling indicated that the presence of Cr-iron (Fe)-bearing mineral phases—notably, FeCr₂O_4, MgCr₂O₄ and Cr(OH)₃) may control the fate of Cr in the tannery wastewater. Environmental risk assessment modeling categorized the tannery wastewater as the ‘worst quality’, which is not fit for use in crop irrigation without treatment. This study highlights that immediate monitoring, remediation and mitigation strategies are required to reduce the risk of Cr exposure from tannery wastewater in many areas of Pakistan.

Global warming poses a serious threat to food security because of its impacts on thermosensitive food crop production. Rice is of paramount significance due to the world’s three-billion-population dependence on it as a staple food. It is well established that the high temperatures at day or night times during the grain-filling period can reduce rice grain yield, although the intriguing impact of high temperatures on head rice yields (HRY) is poorly discussed. This is because high and stable HRY is vital to meet the demand for rice grain, which is a staple food for many developing and developed nations. Hence, identifying the novel heat-tolerant rice germplasm with higher head rice yields may help mitigate a critical problem threatening global food security resulting from climate change. This review addresses the key factors, including pre-and-post-harvest scenarios related to overall reductions in the HRY and how grain molecular composition can play a significant role in determining head rice yields. Moreover, the underlying genetics of head rice is discussed as and possible mechanism to breach the complexity of HRY before identifying the key alleles and genomic regions related to the reduction in the HRY. Future research should focus on understanding the mechanisms of tolerating heat stress in rice by combining modern statistical, physiological, and molecular techniques to increase HRY. This may include high-throughput phenotyping techniques, mapping quantitative loci affecting HRY loss processes and genomic prediction using a broad wild and cultivated rice germplasm.