Globally, climate change could hinder future food security that concurrently implies the importance of investigating drought stress and genotype screening under stressed environments. Hence, the current study was performed to screen 45 diverse maize inbred lines for 18 studied traits comprising phenological, physiological, morphological, and yield characters under optimum and water stress conditions for two successive growing seasons (2018 and 2019). The results showed that growing seasons and water regimes significantly influenced (p < 0.01) most of the studied traits, while inbred lines had a significant effect (p < 0.01) on all of the studied traits. The findings also showed a significant increase in all studied characters under normal conditions compared to drought conditions, except chlorophyll content, transpiration rate, and proline content which exhibited higher levels under water stress conditions. Furthermore, the results of the principal component analysis indicated a notable distinction between the performance of the 45 maize inbred lines under normal and drought conditions. In terms of grain yield, the drought tolerance index (DTI) showed that Nub60 (1.56), followed by Nub32 (1.46), Nub66 (1.45), and GZ603 (1.44) were the highest drought-tolerant inbred lines, whereas Nub46 (0.38) was the lowest drought-tolerant inbred line. These drought-tolerant inbred lines were able to maintain a relatively high grain yield under normal and stress conditions, whereas those drought-sensitive inbred lines showed a decline in grain yield when exposed to drought conditions. The hierarchical clustering analysis based on DTI classified the forty-five maize inbred lines and eighteen measured traits into three column- and row-clusters, as inbred lines in cluster-3 followed by those in cluster-2 exhibited greater drought tolerance in most of the studied traits. Utilizing the multi-trait stability index (MTSI) criterion in this study identified nine inbred lines, including GZ603, as stable genotypes in terms of the eighteen studied traits across four environments. The findings of the current investigation motivate plant breeders to explore the genetic potential of the current maize germplasm, especially in water-stressed environments.

/pdf/determination-of-morpho-physiological-and-yield-traits-of-w2q76la3.pdf

Determination of morpho-physiological and yield traits of maize inbred lines (Zea mays L.) under optimal and drought stress conditions

Although agriculture remains the dominant economic activity in many countries around the world, in recent years this sector has continued to be negatively impacted by climate change leading to food insecurities. This is so because extreme weather conditions induced by climate change are detrimental to most crops and affect the expected quantity of agricultural production. Although there is no way to fully mitigate these natural phenomena, it could be much better if there is information known earlier about the future so that farmers can plan accordingly. Early information sharing about expected crop production may support food insecurity risk reduction. In this regard, this work employs data mining techniques to predict future crop (i.e., Irish potatoes and Maize) harvests using weather and yields historical data for Musanze, a district in Rwanda. The study applies machine learning techniques to predict crop harvests based on weather data and communicate the information about production trends. Weather data and crop yields for Irish potatoes and maize were gathered from various sources. The collected data were analyzed through Random Forest, Polynomial Regression, and Support Vector Regressor. Rainfall and temperature were used as predictors. The models were trained and tested. The results indicate that Random Forest is the best model with root mean square error of 510.8 and 129.9 for potato and maize, respectively, whereas R2 was 0.875 and 0.817 for the same crops datasets. The optimum weather conditions for the optimal crop yield were identified for each crop. The results suggests that Random Forest is recommended model for early crop yield prediction. The findings of this study will go a long way to enhance reliance on data for agriculture and climate change related decisions, especially in low-to-middle income countries such as Rwanda.

https://www.mdpi.com/2077-0472/13/1/225/pdf?version=1673952781

Crop Yield Prediction Using Machine Learning Models: Case of Irish Potato and Maize

/pdf/effects-of-drought-and-high-temperature-on-physiological-and-253rub73.pdf

Effects of drought and high temperature on physiological and biochemical processes, and productivity of plants nanochelates

This investigation was carried out for genetic characterization and determination of drought tolerance of ten Egyptian cultivars of wheat (Triticum aestivum L.), namely Misr 1, Misr 2, Gemmiza 9, Gemmiza 10, Gemmiza 11, Gemmiza 12, Shandawel 1, Giza 168, Giza 171, and Sids 14. These cultivars were grown in two winter seasons: 2018/2019 and 2019/2020 at the experimental farm Fac. of Agric., Suez Canal Univ., Ismailia, Egypt, under two watering regimes: normal (100%) and stress (50% FC) conditions. Six agronomic traits and five tolerance indices, namely stress tolerance (TOL), mean productivity (MP), geometric mean productivity (GMP), yield stability index (YSI), and drought susceptibility index (DSI), were used to evaluate the impact of drought stress. The results reflected Giza 171, Misr 2, and Giza 168 as precious germplasm for breeding of high-yielding drought-tolerant wheat. A highly significant positive correlation was recorded between yield under normal and stress conditions on the one hand and each of MP and GMP on the other hand. In addition, YSI appeared engaged in a highly significant positive correlation with yield under drought conditions only. TOL and DSI appeared insignificantly correlated with yield. Therefore, MP and GMP were reflected as the first runners among indices suitable to distinguish the high-yielding cultivars under drought conditions. At the molecular level, five primers of Start Codon Targeted (SCoT) markers were able to resolve and characterize the studied cultivars, which reflected SCoT as a potent gene-targeting molecular marker, able to characterize and resolve genetic diversity in wheat at the cultivar level using few primers. Therefore, SCoT is a time-efficient molecular marker, and it can efficiently replace indices in characterization of drought-tolerant genotypes with a high confidence level and reasonable cost.

/pdf/genetic-characterization-and-agronomic-evaluation-of-drought-1x73ytqq.pdf

Genetic Characterization and Agronomic Evaluation of Drought Tolerance in Ten Egyptian Wheat (Triticum aestivum L.) Cultivars

Wheat is highly susceptible to heat stress, which significantly reduces grain yield. In this study, we used RNA-seq technology to analyze the transcript expression at three different time-points after heat treatment in three cultivars differing in their susceptibility to heat stress: Jopum, Keumkang, and Olgeuru. A total of 11,751, 8850, and 14,711; 10,959, 7946, and 14,205; and 22,895, 13,060, and 19,408 differentially-expressed genes (log2 fold-change > 1 and FDR (padj) < 0.05) were identified in Jopum, Keumkang, and Olgeuru in the control vs. 6-h, in the control vs. 12-h, and in the 6-h vs. 12-h heat treatment, respectively. Functional enrichment analysis showed that the biological processes for DEGs, such as the cellular response to heat and oxidative stress—and including the removal of superoxide radicals and the positive regulation of superoxide dismutase activity—were significantly enriched among the three comparisons in all three cultivars. Furthermore, we investigated the differential expression patterns of reactive oxygen species (ROS)-scavenging enzymes, heat shock proteins, and heat-stress transcription factors using qRT-PCR to confirm the differences in gene expression among the three varieties under heat stress. This study contributes to a better understanding of the wheat heat-stress response at the early growth stage and the varietal differences in heat tolerance.

/pdf/comparison-of-gene-expression-changes-in-three-wheat-1xdnlox8.pdf

Comparison of Gene Expression Changes in Three Wheat Varieties with Different Susceptibilities to Heat Stress Using RNA-Seq Analysis

Heat stress (HS) is one of the major abiotic stresses affecting the production and quality of wheat. Rising temperatures are particularly threatening to wheat production. A detailed overview of morpho-physio-biochemical responses of wheat to HS is critical to identify various tolerance mechanisms and their use in identifying strategies to safeguard wheat production under changing climates. The development of thermotolerant wheat cultivars using conventional or molecular breeding and transgenic approaches is promising. Over the last decade, different omics approaches have revolutionized the way plant breeders and biotechnologists investigate underlying stress tolerance mechanisms and cellular homeostasis. Therefore, developing genomics, transcriptomics, proteomics, and metabolomics data sets and a deeper understanding of HS tolerance mechanisms of different wheat cultivars are needed. The most reliable method to improve plant resilience to HS must include agronomic management strategies, such as the adoption of climate-smart cultivation practices and use of osmoprotectants and cultured soil microbes. However, looking at the complex nature of HS, the adoption of a holistic approach integrating outcomes of breeding, physiological, agronomical, and biotechnological options is required. Our review aims to provide insights concerning morpho-physiological and molecular impacts, tolerance mechanisms, and adaptation strategies of HS in wheat. This review will help scientific communities in the identification, development, and promotion of thermotolerant wheat cultivars and management strategies to minimize negative impacts of HS.

/pdf/impacts-tolerance-adaptation-and-mitigation-of-heat-stress-2x72ikwq.pdf

Impacts, Tolerance, Adaptation, and Mitigation of Heat Stress on Wheat under Changing Climates

Seed priming technique has a marvelous potential in enhancing seed germination and crop establishment under limited soil moisture conditions, which ultimately increases yield. Therefore, we investigated the effects of seed priming on physiology, growth, yield and antioxidant defense system of pearl millet (Pennisetum glaucum L.) under rain-fed condition. The experiments were conducted under laboratory as well as field conditions comprising three treatments i.e., non-primed seeds (control, T0), priming with tap water (hydropriming) (T1) and priming with 2% KNO3 2% for 6 hours at 25°C followed by shade drying (T2). The results showed that chlorophyll content (10.37–14.15%) and relative water content (RWC) (12.70–13.01%) increased whereas proline (-19.44 to -25%) and soluble sugar (-15.51 to -29.13%) contents decreased on account of seed priming in pearl millet under field conditions. The seed priming significantly improved the plant height, final plant stand and grain weight which resulted in increased yield. Enhanced activities of superoxide dismutase (SOD) (5.89 to 8.10 unit/g/seed/min), catalase (CAT) (22.54 to 39.67 µmol/min/g/seed) and ascorbate peroxidase (APX) (8.92 to 22.10 µmol/cm/min/g) and concomitant decrease in H2O2 and malondialdehyde (MDA) content suggests their role in imparting oxidative tolerance at initial stages of growth in primed seed. The lab studies suggest that the improved yield might be attributes to increased seed germination and seedling vigor. It is recommended that the hydropriming (tap water) or KNO3 (2%) priming of seeds for 6 hours under ambient conditions is effective to enhance growth and yield of pearl millet under rainfed conditions.

/pdf/on-farm-hydro-and-nutri-priming-increases-yield-of-rainfed-iu35tdm6.pdf

On-farm hydro and nutri-priming increases yield of rainfed pearl millet through physio-biochemical adjustments and anti-oxidative defense mechanism

Effect of integrated nutrient management on growth and quality of guava (Psidium guajava L)

A field experiment was conducted during kharif 2015-17 to study the efficacy of growth retardants on physiology and yield of pearl millet at Durgapura (Jaipur). Growth retardants, viz. cycocel and mepiquat chloride were sprayed @ 250, 500 and 750 ppm at tillering (40 DAS) and flowering (60 DAS) stages. The experiment was laid out in randomized block design with 4 replications. Results showed that plant height decreased, whereas chlorophyll content and relative water content increased significantly with the foliar application of mepiquat chloride @ 500 ppm over rest of the treatments. A significantly higher specific leaf weight was noted under cycocel @ 750 ppm over control. Foliar application of mepiquat chloride @ 500 ppm produced significantly higher grain yield over control. However, it was statistically at par with cycocel @ 500 ppm and mepiquat chloride @ 750 ppm. On the other hand, significantly higher fodder yield was registered with the foliar spray of cycocel @ 250 ppm over cycocel @ 500 ppm, cycocel @ 750 ppm, mepiquat chloride @ 250 ppm and 750 ppm that was at par with the control and mepiquat chloride @ 500 ppm. Maximum net returns and benefit cost ratio were accrued under mepiquat chloride @ 500 ppm. Thus, foliar application of mepiquat chloride @ 500 ppm at 40 and 60 DAS could be recommended for obtaining higher grain yield and net returns from pearl millet under rainfed condition of Rajasthan.

/pdf/efficacy-of-growth-retardants-on-physiology-and-yield-of-2ptn014g.pdf

Sunita Gupta

Papers

Impacts, Tolerance, Adaptation, and Mitigation of Heat Stress on Wheat under Changing Climates

On-farm hydro and nutri-priming increases yield of rainfed pearl millet through physio-biochemical adjustments and anti-oxidative defense mechanism

Effect of integrated nutrient management on growth and quality of guava (Psidium guajava L)

Efficacy of growth retardants on physiology and yield of pearl millet under rainfed condition