Journal of Agronomy and Crop Science最新文献

Dirigent (DIR) proteins, localised at cell wall, are involved in phenoxy radical coupling reactions during lignin biosynthesis in plant species and provide resistivity against adverse environmental conditions. The sub family distribution of DIR genes are different among plant species. In present study, we genome wide identified 28 DIR domain containing genes in Jatropha curcas. The phylogenetic analysis classified DIR genes into three distinct subfamilies distributed among clades. The taxonomy of DIR genes into three subfamilies were further confirmed via pairwise sequence similarity as ‘lignan-forming subfamily’ (DIR-a), ‘lignin-forming subfamily’ (DIR-e) and ‘cell wall signaling subfamily’ (DIR-g). The evolutionary aspects of DIR genes evaluated by divergence analysis further recognised the synonymous and non-synonymous changes. We have also studied the molecular characterisation of DIR genes within Jatropha genome for its gene structure organisation, the presence of Light responsive, phytohormone responsive, plant growth responsive and stress responsive cis-regulatory elements in the promotor region, co-expression network with lignin biosynthesis genes, and predicted miRNA target sites, regulated by miRNA mediated post transcriptional regulatory network. Moreover, the biological process enrichment based on gene ontology further revealed the involvement of DIR genes in biosynthetic process of phenylpropanoid and organic substance as well as cellular metabolic process. Subsequently, the co-occurrence of DIR genes with streptophyta taxa's was confirmed mostly in eukaryota. Furthermore, the expression profiles of DIR genes in different tissues of Jatropha under drought stress exhibited significant differential expression. This study provide basis for functional divergence of DIR genes in lignifying plant cell wall and providing protection against environmental stresses in plants.

Day and night high temperatures (HT) has become an inevitable environmental factor in maize production. However, few studies have compared the differences in photosynthetic characteristics of leaves and yield formation during grain filling under daytime HT (DH) and nighttime HT (NH). This study utilised waxy maize and a temperature-controlled pot experiment to assess the impacts of DH, NH and the combination of DH and NH (DNH) treatments at the early filling stage. Compared to the control, three HT treatments resulted in the decrease of grain weight and volume at the middle and late filling stage, and the degree of influence was DNH > DH > NH. During the grain-filling process, DNH and DH treatments reduced the leaf water content, disturbed protein biosynthesis and antioxidant system, accelerated chlorophyll hydrolysis, inhibited phosphoenolpyruvate carboxylase and Ribulose-1,5-bisphosphate carboxylase activities, and reduced post-silking dry matter accumulation and translocation. DNH and DH treatments affected leaf photosynthetic efficiency by changing the gas exchange parameters and PSII reaction, which in turn influenced the maximum photochemical efficiency, electron transport rate, and energy conversion. However, NH treatment only affected some stages of grain filling and had less effect on protein synthesis and antioxidant enzyme activity than DH and DNH. These new findings complement the comparison between DNH in photosynthetic characteristics and yield of waxy maize.

In the relay intercropping of maize and sweet potato, maize brought 40–70 days of shading stress on sweet potato; thus, sweet potato yield was reduced. Morphological and physiological impacts of weak light or shading stress on sweet potato in the early stage are not known. We hypothesised that shading stress would change morphogenesis and physiology of sweet potato in the early stage that leads to low yield. To test this hypothesis, we simulated the shading stress using weak light and applied the shade stress onto two sweet potato cultivars, Yushu-17 and Qianshu-8. Results showed that 45-day weak light caused abnormal growth of sweet potato seedlings. The weak light triggered a smaller diameter, longer internodes and extended length of the main vines on both cultivars. The fresh weight of stems and leaves was less than that under normal light. It was also found that weak light promoted the accumulation of proline (Pro) and malondialdehyde (MDA) that influence osmotic status of the vines. Weak light elevated the activities of both superoxide dismutase (SOD) and catalase (CAT). Although weak light enhanced the content of chlorophyll, it inhibited the net photosynthetic rate (Pn) and sucrose phosphate synthase (SPS), and delayed root development. The yield loss was not reversed by resuming normal light after 60 days of weak light. We conclude that weak light in the early stage impedes normal morphogenesis by disturbing osmotic status and adversely impacting antioxidant and photosynthetic enzymes that led to abnormal growth of the main vines and roots, thus causing yield reduction. These findings may explain the negative impact of the shading stress by maize on the yield of sweet potato in the field.

Evaluating diversity panels for their ability to endure salt stress conditions is essential for the development of breeding lines. A set of 100 lentil genotypes was characterised for their salt tolerance during 2021–22 and 2022–23. Salt stress lead to an average reduction of 43.96% in plant height, 19.46% in primary branches per plant, 44.45% in pods per plant, 47.26% in seed weight, 36.39% in photosynthetic rate (Pn), 34.03% in transpiration rate, 33.95% in stomatal conductance (gsw), 27.75% in chlorophyll content, 30.04% in relative water content and 18.99% in membrane stability index (MSI). The K⁺ content decreased while the Na⁺ content increased in plant tissues of all genotypes with higher salt levels. Notably, genotypes IC241532, IC241529, LL1813, EC223237B, KM4, IC78387, LL1804, KM1, LL1823, LL1641, IC78387 and EC223212A demonstrated superior performance due to an enhanced antioxidant system. It was evidenced by increased proline content, alongside increased activity of superoxide dismutase, catalase, glutathione reductase, aspartate peroxidase activity and higher total soluble sugar content. Interestingly, a positive correlation was observed between yield per plant (YPP) and seed K⁺, shoot K⁺, Pn, gsw, shoot fresh weight (SFW) and root fresh weight (RFW) highlighting the importance of these key traits in enhancing plant tolerance to salt stress. Principal component analysis of 26 indices indicated a considerable level of genotypic variability among genotypes as well as a significant correlation between YPP and SFW, RFW under control and Pn, MSI, gsw, SFW, root dry weight (RDW) and 100-seed weight under salt stress. This study provides valuable insights into diverse lentil genotypes' agro-physiological and antioxidant responses to salt stress.

Salinity stress is becoming an increasingly severe global challenge, necessitating the identification of crop germplasm capable of thriving in saline-alkaline soil conditions to ensure high yields. Naked barley (Hordeum vulgare var. nudum) emerges as a promising candidate due to its resilience to abiotic stresses, high nutritional value, and potential for sustainable production. In this study, a preliminary screening of 440 naked barley genotypes was conducted under saline soil conditions. Key indices, including yield and eleven yield-related components, were evaluated using multivariate analysis techniques such as principal component analysis (PCA), correlation coefficient analysis, and hierarchical cluster analysis. The results demonstrated that spike weight, seed number per row, fully developed seeds per spike, seed weight per spike, thousand-seed weight, and seed width significantly influenced grain yield under saline-alkaline conditions, as indicated by correlation coefficients and PCA. Yield performance classification revealed that 11% of the genotypes were high-yielding, 29% were moderate-yielding, and 60% were low-yielding. Hierarchical cluster analysis further identified that the first cluster (C1), which includes a total of 150 genotypes, exhibited the highest mean values for most of the traits examined. Within this cluster, notable genotypes (X511, X185, X421, X188, X322, X184, X350, X323, X349, and X338) demonstrated yields ranging from 4.32 to 6.68 t/ha. These genotypes, grouped in sub-cluster C1.1.1, represent promising candidates for breeding programmes aimed at enhancing yield and salinity tolerance. This study provides an initial screening of yield potential and lays the foundation for future research into the physiological, biochemical, and molecular mechanisms underlying salinity tolerance and breeding.

Soil salinity severely impacts seed germination, growth and overall crop productivity worldwide. Ellagic acid (EA) and hydrogen peroxide (HP, H₂O₂) play vital roles in plant stress responses, particularly in mitigating the negative effects of salinity. EA, a polyphenolic compound with strong antioxidant properties, helps enhance plant resilience by neutralising reactive oxygen species (ROS), regulating stress-related genes and restoring osmotic balance. HP, although often seen as a harmful ROS, acts as a signalling molecule at low concentrations, promoting stress tolerance by activating antioxidant defences, maintaining ion homeostasis and regulating stomatal function. A pot experiment was conducted to investigate the effects of EA and H₂O₂ on wheat (Triticum aestivum) under saline stress. Two cultivars, salt-tolerant Punjab-85 and salt-sensitive MH-97, were soaked in various concentrations of EA (0, 60 and 120 ppm) and H₂O₂ (0, 55 and 110 ppm) for 6 h. After planting in pots, a saline solution of 150 mM NaCl was applied 2 weeks post germination to induce salt stress. Results showed that H₂O₂ positively affected ash concentration in both cultivars, with lower (55 ppm) and higher (110 ppm) concentrations being most effective for the respective cultivars. The study also found that leaf area, ear length, ear weight, dry weight and productivity were correlated with total chlorophyll content, which was negatively associated with Chl-a, lipids, Na⁺ and Mg²⁺. Combined priming with EA and H₂O₂ had a stronger protective effect than individual treatments, helping alleviate salt stress and promote wheat growth.

Climate change threatens rice production by increasing the frequency of adverse weather conditions, such as continuous rainy and overcast days, which lead to combined low temperature and weak light stress (LTWL) during the rice growing stage. To investigate the impact of LTWL stress on rice grain yield and its physiological mechanisms, we conducted a 2-year study focusing on the panicle differentiation stage. Two rice cultivars were examined: conventional japonica rice and indica-japonica hybrid rice. The experimental treatments consisted of varying durations of LTWL exposure during panicle differentiation, namely T1 (0–7 days), T2 (0–14 days), T3 (0–21 days), T4 (8–14 days), and T5 (15–21 days) in 2021 and 2023, with the addition of T6 (22–28 days) in 2023. In addition, the normal temperature and sunlight treatment were conducted as the control (CK). The results revealed that, compared to the CK treatment, LTWL during panicle differentiation reduced rice grain yield by 6.25%–26.84% for NG9108 and by 3.05%–20.51% for YY2640. This yield reduction was primarily attributed to a decrease in the number of grains per panicle, with NG9108 experiencing a range of 4.60%–22.62% and YY2640 showing a range of 1.76%–20.14%, which resulted from reduced spikelet differentiation and increased spikelet degeneration. Among the 7-day LTWL treatments, the T5 treatment caused the most significant yield loss. Furthermore, as the duration of the LTWL stress increased, the decline in grain yield became more substantial. For the two types of cultivars, conventional japonica rice was more sensitive to LTWL treatments compared to the indica-japonica hybrid rice. Physiological analysis indicated that LTWL treatments enhanced internode elongation and increased leaf SPAD values. Additionally, the activity of antioxidant enzymes was elevated, suggesting a stress response to mitigate oxidative damage. However, LTWL stress also reduced leaf photosynthetic rates and root activity, which collectively contributed to the observed decline in grain yield during panicle differentiation.