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Melatonin is a pleiotropic signaling molecule that reduces the adverse effects of abiotic stresses, and enhances the growth and physiological function of many plant species. Several recent studies have demonstrated the pivotal role of melatonin in plant functions, specifically its regulation of crop growth and yield. However, a comprehensive understanding of melatonin, which regulates crop growth and yield under abiotic stress conditions, is not yet available. This review focuses on the progress of research on the biosynthesis, distribution, and metabolism of melatonin, and its multiple complex functions in plants and its role in the mechanisms of metabolism regulation in plants grown under abiotic stresses. In this review, we focused on the pivotal role of melatonin in the enhancement of plant growth and regulation of crop yield, and elucidated its interactions with nitric oxide (NO) and auxin (IAA, indole-3-acetic acid) when plants are grown under various abiotic stresses. The present review revealed that the endogenousapplication of melatonin to plants, and its interactions with NO and IAA, enhanced plant growth and yield under various abiotic stresses. The interaction of melatonin with NO regulated plant morphophysiological and biochemical activities, mediated by the G protein-coupled receptor and synthesis genes. The interaction of melatonin with IAA enhanced plant growth and physiological function by increasing the levels of IAA, synthesis, and polar transport. Our aim was to provide a comprehensive review of the performance of melatonin under various abiotic stresses, and, therefore, further explicate the mechanisms that plant hormones use to regulate plant growth and yield under abiotic stresses.

Plant density is one of the most important factors influencing the physiological, morphological characteristics, and yield of sesame. Sesame is an important oilseed and cash crop production in Sudan. The effects of different rows spacing on the growth attributes, yield and yield compound on three sesame seeds varieties were investigated at rainfall conditions in semi-arid regions. Two field experiments were conducted in 2014-2015 and 2015-2016. Three varieties were planted at four rows spacing [5(control), 10, 20 and 30cm]. The experiment was laid out in RCBD in split plots with three replications. There were significant differences between row spacing, varieties and interaction between row spacing and varieties for all parameters except the 1000 seeds weight. Moreover, Abo Nama has recorded the highest plants, number of branches and number of capsules per plant, while the abo Radom recorded the highest number of seeds per capsule and seed yield, and abo sofa had the highest weight of 1000 seeds. Planted varieties at the 5 cm between rows can increase the seed yield (210.18 kg/h). The interaction between Abo Radom and control recorded the high seed yield by 265.30 kg per h-1. This study suggests that the appropriate rows spacing can actively increase the yield of the sesame plant.

Wheat (Triticum aestivum L.) seedling establishment is very sensitive to temperature and drought stresses. The present study was conducted to investigate the effects of foliar exogenous 5-aminolevulinic acid (5-ALA) application on wheat seedling under different temperature (25, 30, and 35 ℃) and water regimes (normal and 65% watering). Five different levels of 5-ALA (0, 25, 50, 100 and 150 mg L-1) were applied as foliar application. Leaf area, stem diameter, shoot and root lengths, fresh and dry weights of shoot and root, and physiological parameters were measured. Drought stress (W2) decreased leaf area by 14.9% compared with normal watering (W1). High temperature (35 ℃) increased malondialdehyde (MDA) content by 72.1% compared with control (25 ℃). 35 ℃ with W2 reduced root and shoot dry weights by 71.8% and 51.9% relative to 25 ℃ and W1. At 35 ℃, 25 mg L-1 5-ALA increased root length by 17.1% and 3.4% at W1 and W2, respectively. 150 mg L-1 5-ALA increased root fresh weight by 101.0% compared with 0 mg L-1 5-ALA at W1 and 35 ℃. The highest protein content (8.35 mg g-1 FW) was achieved at the interaction between W2, 35 ℃ and 50 mg L-1 5-ALA. At W2 and 35 ℃, 150 mg L-1 5-ALA increased proline content by 66.5% relative to 0 mg L-1. The results of the present study suggest that foliar application of 5-ALA could be useful to alleviate the temperature and/or drought stresses of wheat seedling.

Salinity is a growing problem worldwide and techniques are needed to mitigate this problem. The experiment was conducted to examine if biochar could improve growth, physiological response, and DM yield of forage sorghum (Sorghum bicolor (L.) Moench) under saline conditions. Sorghum seedlings were transplanted in sandy loam soil (0-20 cm layer of a Typic Fluvaquents Entisols) treated with sodium chloride at rates of 0.26, 5.8, and 12.6 dS m-1. The saline soil was treated with four biochar rates, 0%, 2.5%, 5%, and 10% (w/w). Plant height, fresh weight, photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) were affected by the interaction between salinity and biochar. At the 12.6 dS m-1 salinity rate, 5% biochar increased plant height, leaf area, fresh weight, DM yields, A, gs, and E by 20.1%, 16.5%, 26.2%, 27.4%, 14.5%, 31.1%, and 26.7%, respectively. At the 12.6 dS m-1 salinity rate, 5% biochar decreased CAT, POD, and SOD by 56.8%, 44.8%, and 18.9%, respectively. Furthermore, among all biochar rates used in this investigation, the 5% rate had a better result for forage sorghum production. These findings demonstrated that the lowest biochar soil amendment application could alleviate the harmful impact of salinity; a high biochar application rate can have a negative influence.

Salinity is a growing problem worldwide and techniques are needed to mitigate this problem. Field experiments were conducted to explore the effects of optimum N management (NM) on growth, antioxidant ability and yield performance of rice (Oryza sativa L.) in medium saline soil in the coastal area of Yancheng City, Jiangsu Province, China, during 2016 and 2017. A salt tolerant rice genotype Nangeng 9108 and N fertilizer including urea (300 kg N ha-1) were used, six levels of NM were arranged (base:tillering:panicle initiation fertilizers = 0:8:2 (T1), 0:6:4 (T2), 0:4:6 (T3), 5.6:2.4:2.0 (T4), 4.2:1.8:4.0 (T5), and 2.8:1.2:6.0 (T6), respectively). NM significantly affected plant growth, antioxidant traits, yield and yield components of rice in saline soil. On average, grain yield, panicles and spikelets per panicles were prominently higher under treatments of applied basal fertilizer (TABF; T4, T5 and T6) than treatments of non-applied basal fertilizer (TNBF; T1, T2 and T3). The TABF produced a yield advantaged of 39.7% and 54.4% over TNBF in 2016 and 2017, respectively. Bigger panicles were formed under TABF, mean spikelets per panicle was 15.7% higher than TNBF in 2016 and 20.0% in 2017. The T5 produced the highest dry weight, grain yield, panicles, spikelets per panicle, activities of catalase, peroxidase and superoxide dismutase, soluble protein, soluble sugar and sucrose at each growth period. However, the highest grain filling percentage showed under T4 had 82% and 81% advantages in each year. These results suggest that applied basal fertilizer can enhance salt tolerance and grain yield of rice, and appropriate N management can alleviate salt stress and increase grain yield.

Germination is a very sensitive stage for the harmful effect of salinity stress. Plants respond differently to different types of salt. Gibberellic acid (GA3) is the most important hormone to mitigate salt stress. A controlled germination study was conducted to evaluate the impact of different salts (0, 150 mM NaCl, and 150 mM Na2SO4) and different GA3 concentrations (0, 50, 100, 250, and 300 mg L-1) on the germination of the two most used Sudanese sorghum (Sorghum bicolor [L.] Moench) varieties Wadahmed and Tabat. The studied parameters were seed water uptake after 8 h imbibition, germination percentage, germination rate, shoot and root length, shoot and root fresh weight, shoot and root dry weight, and seed vigor index. Results showed that Na2SO4 reduced germination percentage, germination rate, shoot length, root length, root fresh weight, shoot dry weight, root dry weight, and seed vigor index by 17.0%, 50.0%, 86.99%, 89.03%, 76.8%, 54.5%, 66.6%, and 89.7%, respectively, when compared with the non-saline treatment. The maximum values for seed water uptake, germination percentage, germination rate, shoot length, and seed vigor index were achieved at 100 mg L-1 GA3. The Na2SO4 salt had a more harmful effect than NaCl. The 100 mg L-1 GA3 concentration can be recommended to improve seed water uptake, germination parameters, and seedling growth under salt stress in the two Sudanese sorghum varieties (Wadahmed and Tabat). ‘Wadahmed’ was more tolerant to salinity stress than ‘Tabat’ at the germination stage.

Castor bean (Ricinus communis L.) as a bioenergy crop, received more and more attention in recent years. However, the yield of castor bean seeds is affected by adverse environmental conditions. The objective of this study was to assess the effects of exogenous application of Paclobutrazol (PBZ) on castor bean growth, yield and physiology as well as on its response to environmental stress during grain filling. In the present field study, three PBZ concentrations [0 g•ha-1 (control), 75 g•ha-1 and 150 g•ha-1] were applied twice, once at grain filling of main panicle and once at grain filling of branched panicle. The growth and physiological responses of castor bean were measured four times throughout flowering and seed formation stages [1-early initiation stage of main inflorescence (E), 2- anthesis of main inflorescence (A), 3-maturity of main panicle (M) and 4-maturity of branched panicle (B)]. Plant growth was not affected by the application of PBZ, but leaves remained later on the plant when 75 g•ha-1 of PBZ was applied. With the application of PBZ, the concentration of starch was higher in panicles than in leaves and stems. Also, PBZ application increased the number of seeds per plant without affecting seed size and weight. These results suggest that exogenous application of PBZ can enhance sink strength of panicles and improve seed yield and that application of PBZ at flower initiation can alter photosynthetic partitioning in favor to seed production. On the other hand, PBZ had no effect on antioxidant enzyme activity in the seeds in response to stress.

Background Information about Chronic obstructive pulmonary diseases (COPD)-related health resources allocation in China is very limited. The aim of the study was to explore the distribution of COPD-related health resources allocation among different levels public hospitals (PHs) in Hunan Province of central south China. Methods: We randomly collected data from 57 Public Hospitals (PHs) at 3 different levels in Hunan province as well as 893 pulmonary physicians (PPs) who worked there in 2009. Questionnaires based on the recommendations of COPD guideline were designed, including availability of spirometers, inhaled agents for COPD and COPD-related health education for local residents, as well as PPs’ educational levels. Results: Spirometers equipped ratio in 3rd level PHs was much higher than 1st, 2nd PHs. The disparity varied vastly form 0% to 100%. The inhaled agents equipped ratio was 5.56%, 70.85% and 100% respectively for the 1st, 2nd and 3rd levels PHs. No 1st level PHs launched COPD-related healthcare education for local residents, only 10 of 24 for the 2nd level PHs and 10 of 15 for the 3rd level PHs. PPs of high educational levels concentrate in 3rd levels PHs, however, PPs working in 1st levels PHs and 2nd levels PHs were mainly low and median educational levels PPs’ knowledge of COPD of 3rd levels PHs was much better than of 1st levels PHs and 2nd levels PHs. Conclusion: The extreme imbalance and disparity existed in COPD-related health resources allocation at three levels PHs in central south China. Inequity and insufficient in COPD-related health resources in 1st and 2nd levels PHs should be improved.