Primed to fail: Primed acclimation to water stress can lead to greater disease severity and reduced yields in Sclerotium rolfsii-inoculated cultivated peanut (Arachis hypogaea L.).

Ameliorative roles of biochar-based fertilizer on morpho-physiological traits, nutrient uptake and yield in peanut (Arachis hypogaea L.) under water stress

Identification of genes differentially expressed during early interactions between the stem rot fungus (Sclerotium rolfsii) and peanut (Arachis hypogaea) cultivars with increasing disease resistance levels

Seedlings of two peanut cultivars (TPT-1 and TPT-4) grown in distilled water for 12 d were subjected to polyethylene glycal (PEG-6000) induced water stress. Twenty mM CaCl2 was added to the stressed seedlings to examine the ameliorative effect of PEG induced water stress. The seedlings were analysed for calcium content at 2-d intervals for 7 d. Calcium-binding proteins (CaBPs) were quantified in the seedlings of different treatments in the two cultivars. Water stressed seedlings had significantly lower calcium content. The seedlings of the two cultivars showed differences in the accumulation of calcium under treatments. CaBPs fractionated through DEAE cellulose columns. The pooled fractions of the proteins separated by SDS-PAGE contained different molecular weights of polypeptides. The polypeptides were resolved on the CaCl2-treated seedlings better than either control or water stressed and PEG + CaCl2 treated seedlings. Calmodulin isolated from the seedlings of both the cultivars showed a single band co-migrating with 15 kDa protein of Bovine brain calmodulin. Differences between the cultivars, treatments and interaction for the parameters were significant. The two cultivars showed differences in calcium-binding proteins under PEG-induced water stress and its alleviation by CaCl2 in peanut seedlings.

Applying fungicides at night when the leaves are folded and using irrigation water after application have both been shown to increase deposition of fungicides in the lower plant canopy, improve control of stem rot (caused by Sclerotium rolfsii), and increase peanut (Arachis hypogaea) yield. To evaluate the interactive effects of these two practices, four applications of a protectant fungicide, chlorothalonil (1.26 kg a.i./ha), or a systemic, prothioconazole + tebuconazole (0.23 kg a.i./ha), tebuconazole (0.21 kg a.i./ha), flutolanil + propiconazole (0.45 kg a.i./ha), pyraclostrobin (0.21 kg a.i./ha), or two applications of a systemic, fluoxastrobin (0.17 kg a.i./ha) or azoxystrobin (0.31 kg a.i./ha) were sprayed either at night (3 a.m. to 5 a.m., when peanut leaves were folded) or during daylight (10 a.m. to 12 p.m., when peanut leaves were unfolded). Fungicides were applied as sub-subplots and night and day fungicide application timings as subplots in a split-split plot design with post-spray irrigation and nonpost-spray irrigation as whole plots to evaluate disease control and peanut yield in 2008 and 2009. In 2008, leaf spot intensity (early leaf spot caused by Cercospora arachidicola) was low and disease control was similar regardless of application timing or fungicide across post-spray irrigation treatments. In 2009, leaf spot was severe and disease control for night and day applications of a systemic fungicide was similar across post-spray irrigation, but pyraclostrobin and prothioconazole + tebuconazole had the lowest ratings. Interaction of fungicide, application timing and post-spray irrigation was significant for stem rot and yield. Night application of prothioconazole + tebuconazole, flutolanil + propiconazole or pyraclostrobin showed the most increase in stem rot control and yield compared with day application among the evaluated fungicides, but the positive effects on stem rot control and yield were minimal with post-spray irrigation. The effects of application timing and post-spray irrigation on fungicide efficacy were not the same for all fungicides.

Peanut (Arachis hypogaea L.) yield and quality can be influenced by gypsum application. The objective of this study, conducted in 2001 and 2002, was to evaluate the influence of two gypsum applications (0 and 500 lb/acre) on yields and quality of two peanut cultivars (‘Georgia Green’ and ‘C‐99R’). Peanut quality test included sound mature kernels riding screen (SMKRS); sound splits; total sound mature kernels (TSMK); other kernels; and total damage, kernels, and hulls. Peanut yields were higher with gypsum application (4343 lb/acre) compared to the treatment without gypsum application (3926 lb/acre) in one of two years. A lower percentage of TSMK (72 and 74%) and greater percentage of total hulls (23 and 22%) were observed when gypsum was applied in one of two years compared to the treatment without gypsum. Averaged across years, a greater percentage of other kernels was observed with gypsum application (4.6%) than without gypsum (4.0%). Cultivar did not influence peanut yields. The percentage of total damage was greater in 2001 (0.8 and 0.1%) and less in 2002 (0.4 and 1.3%) for Georgia Green than C‐99R peanuts, respectively. Greater percentages of SMKRS, TSMK, total kernels, and less sound splits and total hulls were obtained for Georgia Green than C‐99R peanuts. The results of this study indicate that gypsum applications may help to increase peanut yields in years with higher yields likely due to adequate availability of Ca in the fruiting zone.

Crop production is increasingly threatened by the escalating weather events and rising temperatures associated with global climate change. Plants have evolved adaptive mechanisms, including stress memory, to cope with abiotic stresses such as heat, drought, and salinity. Stress memory involves priming, where plants remember prior stress exposures, providing enhanced responses to subsequent stress events. Stress memory can manifest as somatic, intergenerational, or transgenerational memory, persisting for different durations. The chromatin, a central regulator of gene expression, undergoes modifications like DNA acetylation, methylation, and histone variations in response to abiotic stress. Histone modifications, such as H3K4me3 and acetylation, play crucial roles in regulating gene expression. Abiotic stresses like drought and salinity are significant challenges to crop production, leading to yield reductions. Plant responses to stress involve strategies like escape, avoidance, and tolerance, each influencing growth stages differently. Soil salinity affects plant growth by disrupting water potential, causing ion toxicity, and inhibiting nutrient uptake. Understanding plant responses to these stresses requires insights into histone-mediated modifications, chromatin remodeling, and the role of small RNAs in stress memory. Histone-mediated modifications, including acetylation and methylation, contribute to epigenetic stress memory, influencing plant adaptation to environmental stressors. Chromatin remodeling play a crucial role in abiotic stress responses, affecting the expression of stress-related genes. Small RNAs; miRNAs and siRNAs, participate in stress memory pathways by guiding DNA methylation and histone modifications. The interplay of these epigenetic mechanisms helps plants adapt to recurring stress events and enhance their resilience. In conclusion, unraveling the epigenetic mechanisms in plant responses to abiotic stresses provides valuable insights for developing resilient agricultural techniques. Understanding how plants utilize stress memory, histone modifications, chromatin remodeling, and small RNAs is crucial for designing strategies to mitigate the impact of climate change on crop production and global food security.

The differential response of peanut (Arachis hypogaea L.) cultivars to soil applications of Ca has been established for many years. Recent research reports, however, have indicated that peanut cultivars respond similarly to Ca application. This may result in part from new peanut cultivars differing in their response to Ca. Experiments were therefore conducted on a low Ca soil to measure responses of three commonly grown peanut cultivars to soil‐applied Ca.Gypsum was applied at 0 and 1,121 kg/ha in a split‐plot design using ‘Florunner,’ ‘Florigiant,’ and ‘NC‐Fla 14’ peanut cultivars. Other nutrients were applied uniformly. Yield, sound mature kernels (SMK), extra large kernels (ELK), and % N and oil in the seed were measured.Results from this experiment show that gypsum had no effect on yield or sound mature kernels of Florunner peanuts. Florunner peanuts produced higher yields and grades than Florigiant or NC‐Fla 14, regardless of treatments. Gypsum application to Florigiant and NC‐Fla 14 peanuts increased yields, sound mature kernels, and extra large kernels. In general, gypsum increased the % oil in all cultivars. Florigiant contained less oil than the other cultivars. Nitrogen content of the seed of all cultivars was reduced by gypsum application. These data indicate that on low Ca soils Florunner peanuts can produce higher yields and quality with or without gypsum, while Florigiant and NC‐Fla 14 need gypsum fertilization to increase yield and improve quality.

Factors such as the selection of cultivars and the planted density affect the development and yield of peanuts (Arachis hypogaea L.). This study’s objective was to evaluate peanut cultivars’ agronomic behavior under three planting densities in the northeast of Peru. The design used was randomized complete blocks (DBCAs) with a bifactorial arrangement 4A × 3B (factor A, peanut cultivars; factor B, planting densities), forming 12 treatments with three replications per block. The results revealed that T3 (Huayabamba cultivar + density of 30 × 50 cm) stood out, presenting the most favorable means in the number of pods (16 pods), number of seeds per pod (five seeds), height at 90 days (22.7 cm), and yield (1850 kg/ha). Empty pods did not show significant differences between treatments. T8 (Chivita cultivar + density of 20 × 50 cm) indicated the highest number of branches (six branches); in the weight of 100 seeds, the Rojo Tarapoto cultivar was the most encouraging, adapting optimally to the three densities. In addition, T7 (chivita cultivar + density of 10 × 50 cm) showed the shortest days at flowering and harvest, with 64 and 134 days. The study showed that T3 was the most efficient in pod and seed production, making it crucial to optimizing peanut yield.

Strip tillage with various crop covers in peanut (Arachis hypogaea, L.) production has not shown a clear yield advantage over conventional tillage, but has been found to reduce yield losses from some diseases. This study was conducted to determine pod yield and disease incidence between two tillage practices, five winter cover crops, three peanut cultivars, and three fungicide programs. Conventional and strip tillage treatments were implemented on a Greenville sandy loam (fine, kaolinitic, thermic Rhodic Kandiudults) near Shellman, GA. Five winter cereal grain cover crops (strip tillage) and a no-cover crop treatment were sprayed at recommended (1R), half recommended (0.5R) or untreated (0R) fungicide programs. Within peanut cultivars, leaf spot (Cercospora arachidicola Hori) intensity decreased as the number of fungicide applications increased; however, stem rot (Sclerotium rolfsii) incidence was the same for the 1R and 0.5R fungicide programs but increased 0R program. Conventional tilled peanuts developed more leaf spot compared with strip tillage. There was no difference in leaf spot ratings among winter crop covers. There was no difference in stem rot incidence with tillage or winter cover crop. There was no yield difference with peanut cultivar. Pod yield was the same for the 1R and 0.5R fungicide program (3867 kg/ha) but decreased at the 0R fungicide program (2740 kg/ha). Pod yield was greater with conventional tillage and strip tillage with black oats (Avena sativa L.) (3706 kg/ha) compared with strip tillage of other winter crop cover treatments (3358 kg/ha). Conventional tillage had more leaf spot, equal incidence of stem rot, and higher yield compared with strip tillage. The 0.5R fungicide program had the same yield compared with the 1R fungicide program implying a possible 50% savings on fungicide applications on well rotated fields with lower disease risk.

Priming crops for the future: rewiring stress memory.

Genotypic variation in crop response to drought depends on agronomic, environmental and genetic factors, and only limited work has compared responses of crop species to water limitation. Twenty genotypes of peanut (Arachis hypogaea L.) and of cowpea (Vigna unguiculata (L.) Walp) were tested in lysimeters under well-watered (WW) and water-stress (WS) conditions during two seasons, a post-rainy season with high evapotranspiration and a rainy season with low evapotranspiration (ET), in order to assess: (i) variability in the agronomic response to stress within and between species across the seasons; (ii) the water requirement of the two crops in each season; and (iii) the stress effect on harvest index (HI), transpiration efficiency (TE), pod yield and haulm yield. Cowpea required less water than peanut during the two seasons, and water use in cowpea varied less across seasons than in peanut. Peanut yield was more sensitive to water stress than cowpea yield, although its water use under WS was higher than in cowpea. Also, under WS conditions, TE, HI and pod yield were more stable across season in cowpea than in peanut. In the post-rainy season, the decrease in pod yield and HI under WS was higher in peanut (95% and 80%, respectively) than in cowpea (70% and 35%). In addition, TE was less affected by WS in cowpea (5%) than in peanut (24%). HI explained a large part of yield variation in both crops, especially under WS. Under WW, water use explained a large portion of the residual yield variations unexplained by HI, although TE also explained a substantial part of the variation in cowpea. Under WS, the main determinant of residual yield variations in both crops was TE. Generally, genetic variation for water use, TE and HI was found in both species across water regimes and seasons. A notable exception was the absence of variation in peanut water use and TE in the rainy season. Our results showed that cowpea, with lower water requirement and efficient water use under a high-ET season, was more resilient to water-limited and high-ET conditions than peanut.

Huanglongbing (HLB), also referred to as citrus greening disease has caused significant losses to the citrus industry in the United States and elsewhere. In our previous studies, we observed the fluctuation of some primary and secondary metabolites in response to biotic (psyllids feeding that transfers bacteria; i.e., Candidatus Liberibacter spp. that cause greening disease) and abiotic (water deficit) stress factors in citrus. In the current report, we evaluated the changes in polyphenolic compounds in Satsuma leaves in response to Asian citrus psyllid feeding stress and the water stress. In general, polyphenolic levels increased in Satsuma leaves in response to insect and water stress. Specifically, polyphenols such as chlorogenic acid, rutin, diosmin, luteolin 7-O-glucoside, and narangin levels increased significantly in response to both biotic and abiotic stress. On the other hand, while caffeic acid levels significantly increased in water stressed plants, their levels drastically declined to the level of being undetectable in leaves stressed by psyllid feeding. Differences between the two types of stresses were also observed in the levels of apigenin 7-O-glucoside where it decreased significantly in water stressed leaves but not in leaves stressed by psyllid feeding; i.e. changes in the levels of apigenin 7-O-glucoside and caffeic acid were opposite in response to water or feeding stresses. Hesperidin levels were not affected by the water stress or by psyllid feeding. The findings may help to better understanding plant psyllid interactions and may be helpful in developing effective management practices to control the spread of citrus greening disease.

Mesocarp hull color is the current standard to estimate digging date and peanut (<i>Arachis hypogaea</i>, L.) maturity with acceptable yield and grade. Subjectivity of pod color and pod placement on a color chart may give a false indication of when to dig peanuts. The objective was to determine if peg strength could be used to predict pod maturity, digging date, and resultant peanut yield. Peanut peg strength was collected for two years (2011 and 2012) on three peanut cultivars (Georgia-06G, Georgia-09B, and Tifguard), at multiple plant dates (2012 only) and multiple harvest dates to determine the relationship between peg strength versus pod maturity, peanut loss, and peanut yield. Peg strength was determined using an electronic force gage that would measure peak force. Average peg strength was different for all three cultivars with Georgia-06G having the greatest average peg strength followed by Georgia-09B, and Tifguard. In general, peanut yields were greater at early plant and harvest dates and decreased with time. Conversely, peanut pod loss was lower with early plant and harvest dates but increased with later harvest dates. There was a strong positive linear relationship between peg strength and peanut yield for each cultivar. However, there was a relatively small difference with peg strength values between the maximum and minimum peanut yield. There was no relationship between peg strength and mesocarp color (pod maturity, R² = 0.007). Small differences in peg strength and the non-relationship between peg strength and pod maturity implies: 1) a large sample size would be needed to predict peanut yield, 2) the large sample size would increase time and manpower to determine average peg strength values, and 3) peg strength was not a valid criteria to determine pod maturity or predict digging date. Overall, peg strength may be useful to describe cultivar characteristics but may not be sufficiently robust to predict pod maturity digging date, or peanut yield.

Mesocarp hull color is the current standard to estimate digging date and peanut (Arachis hypogaea, L.) maturity with acceptable yield and grade. Subjectivity of pod color and pod placement on a color chart may give a false indication of when to dig peanuts. The objective was to determine if peg strength could be used to predict pod maturity, digging date, and resultant peanut yield. Peanut peg strength was collected for two years (2011 and 2012) on three peanut cultivars (Georgia-06G, Georgia-09B, and Tifguard), at multiple plant dates (2012 only) and multiple harvest dates to determine the relationship between peg strength versus pod maturity, peanut loss, and peanut yield. Peg strength was determined using an electronic force gage that would measure peak force. Average peg strength was different for all three cultivars with Georgia-06G having the greatest average peg strength followed by Georgia-09B, and Tifguard. In general, peanut yields were greater at early plant and harvest dates and decreased with time. Conversely, peanut pod loss was lower with early plant and harvest dates but increased with later harvest dates. There was a strong positive linear relationship between peg strength and peanut yield for each cultivar. However, there was a relatively small difference with peg strength values between the maximum and minimum peanut yield. There was no relationship between peg strength and mesocarp color (pod maturity, R2 = 0.007). Small differences in peg strength and the non-relationship between peg strength and pod maturity implies: 1) a large sample size would be needed to predict peanut yield, 2) the large sample size would increase time and manpower to determine average peg strength values, and 3) peg strength was not a valid criteria to determine pod maturity or predict digging date. Overall, peg strength may be useful to describe cultivar characteristics but may not be sufficiently robust to predict pod maturity digging date, or peanut yield.

Main conclusionEnvironmental-friendly techniques based on plant stress memory, cross-stress tolerance, and seed priming help sustainable agriculture by mitigating negative effects of dehydration stress.The frequently uneven rainfall distribution caused by global warming will lead to more irregular and multiple abiotic stresses, such as heat stress, dehydration stress, cold stress or the combination of these stresses. Dehydration stress is one of the major environmental factors affecting the survival rate and productivity of plants. Hence, there is an urgent need to develop improved resilient varieties. Presently, technologies based on plant stress memory, cross-stress tolerance and priming of seeds represent fruitful and promising areas of future research and applied agricultural science. In this review, we will provide an overview of plant drought stress memory from physiological, biochemical, molecular and epigenetic perspectives. Drought priming-induced cross-stress tolerance to cold and heat stress will be discussed and the application of seed priming will be illustrated for different species.