Nutrient requirements of beef cattle

Drought stress, being the inevitable factor that exists in various environments without recognizing borders and no clear warning thereby hampering plant biomass production, quality, and energy. It is the key important environmental stress that occurs due to temperature dynamics, light intensity, and low rainfall. Despite this, its cumulative, not obvious impact and multidimensional nature severely affects the plant morphological, physiological, biochemical and molecular attributes with adverse impact on photosynthetic capacity. Coping with water scarcity, plants evolve various complex resistance and adaptation mechanisms including physiological and biochemical responses, which differ with species level. The sophisticated adaptation mechanisms and regularity network that improves the water stress tolerance and adaptation in plants are briefly discussed. Growth pattern and structural dynamics, reduction in transpiration loss through altering stomatal conductance and distribution, leaf rolling, root to shoot ratio dynamics, root length increment, accumulation of compatible solutes, enhancement in transpiration efficiency, osmotic and hormonal regulation, and delayed senescence are the strategies that are adopted by plants under water deficit. Approaches for drought stress alleviations are breeding strategies, molecular and genomics perspectives with special emphasis on the omics technology alteration i.e., metabolomics, proteomics, genomics, transcriptomics, glyomics and phenomics that improve the stress tolerance in plants. For drought stress induction, seed priming, growth hormones, osmoprotectants, silicon (Si), selenium (Se) and potassium application are worth using under drought stress conditions in plants. In addition, drought adaptation through microbes, hydrogel, nanoparticles applications and metabolic engineering techniques that regulate the antioxidant enzymes activity for adaptation to drought stress in plants, enhancing plant tolerance through maintenance in cell homeostasis and ameliorates the adverse effects of water stress are of great potential in agriculture.

Drought Stress Impacts on Plants and Different Approaches to Alleviate Its Adverse Effects.

Melatonin is a pleiotropic molecule with multiple functions in plants. Since the discovery of melatonin in plants, numerous studies have provided insight into the biosynthesis, catabolism, and physiological and biochemical functions of this important molecule. Here, we describe the biosynthesis of melatonin from tryptophan, as well as its various degradation pathways in plants. The identification of a putative melatonin receptor in plants has led to the hypothesis that melatonin is a hormone involved in regulating plant growth, aerial organ development, root morphology, and the floral transition. The universal antioxidant activity of melatonin and its role in preserving chlorophyll might explain its anti-senescence capacity in aging leaves. An impressive amount of research has focused on the role of melatonin in modulating postharvest fruit ripening by regulating the expression of ethylene-related genes. Recent evidence also indicated that melatonin functions in the plant's response to biotic stress, cooperating with other phytohormones and well-known molecules such as reactive oxygen species and nitric oxide. Finally, great progress has been made towards understanding how melatonin alleviates the effects of various abiotic stresses, including salt, drought, extreme temperature, and heavy metal stress. Given its diverse roles, we propose that melatonin is a master regulator in plants.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/jipb.12993

Melatonin: A master regulator of plant development and stress responses.

We conducted a study to evaluate the interactive effect of NO and H2 S on the cadmium (Cd) tolerance of wheat. Cadmium stress considerably reduced total dry weight, chlorophyll a and b content and ratio of Fv/Fm by 36.7, 48.6, 26.7 and 19.5%, respectively, but significantly enhanced the levels of hydrogen peroxide (H2 O2 ) and malondialdehyde (MDA), endogenous H2 S and NO, and the activities of antioxidant enzymes. Exogenously applied sodium nitroprusside (SNP) and sodium hydrosulfide (NaHS), donors of NO and H2 S, respectively, enhanced total plant dry matter by 47.8 and 39.1%, chlorophyll a by 92.3 and 61.5%, chlorophyll b content by 29.1 and 27.2%, Fv/Fm ratio by 19.7 and 15.2%, respectively, and the activities of antioxidant enzymes, but lowered oxidative stress and proline content in Cd-stressed wheat plants. NaHS and SNP also considerably limited both the uptake and translocation of Cd, thereby improving the levels of some key mineral nutrients in the plants. Enhanced levels of NO and H2 S induced by NaHS were reversed by hypotuarine application, but they were substantially reduced almost to 50% by cPTIO (a NO scavenger) application. Hypotuarine was not effective, but cPTIO was highly effective in reducing the levels of NO and H2 S produced by SNP in the roots of Cd-stressed plants. The results showed that interactive effect of NO and H2 S can considerably improve plant resistance against Cd toxicity by reducing oxidative stress and uptake of Cd in plants as well as by enhancing antioxidative defence system and uptake of some essential mineral nutrients.

Responses of nitric oxide and hydrogen sulfide in regulating oxidative defence system in wheat plants grown under cadmium stress

Simultaneous mitigation of cadmium and drought stress in wheat by soil application of iron nanoparticles.

Melatonin-mediated nitric oxide improves tolerance to cadmium toxicity by reducing oxidative stress in wheat plants.

Melatonin (MT) and nitric oxide (NO) are known as scavengers of free radicals and an antioxidant against biotic and abiotic stresses in plant defense systems. However, whether NO interplays role in MT-induced antioxidant defense remains to be determined in the plants exposed to lead (Pb) toxicity. So, two experiments were designed to evaluate the role of NO in MT-mediated tolerance of maize plants to Pb stress. In the initial experiment, prior to starting different treatments, a solution of 0.05- or 0.10-mM MT was sprayed every other day for a period of 10 days to the leaves of maize plants exposed to Pb stress (0.1-mM PbCl2). Pb toxicity significantly caused reduction in plant biomass (both fresh and dry), PSII maximum efficiency (Fv/Fm), total chlorophyll, leaf potassium (K), calcium (Ca), and leaf water potential, but it resulted in increased levels of proline, hydrogen peroxide (H2O2), malondialdehyde (MDA), electron leakage (EL), leaf Pb, and endogenous NO. An addition experiment was set up to further understand whether NO played role in mitigation of Pb toxicity in maize plants by MT using scavengers of NO and cPTIO combined with the MT treatments. MT-induced tolerance to Pb toxicity was totally eliminated by cPTIO by reversing endogenous NO. The present results clearly indicated that MT mediated the endogenous NO to improve tolerance of maize plants to Pb toxicity. This evidence was also supported by the increases of H2O2 and MDA and reduces some antioxidant enzyme activities tested as well as the plant growth inhibition and increased leaf Pb content by application of MT combined with cPTIO.

The role of endogenous nitric oxide in melatonin-improved tolerance to lead toxicity in maize plants.

Water pillow irrigation compared to furrow irrigation for soybean production in a semi-arid area

A two-year experiment was conducted in Karacadag rangeland, Sanliurfa, Turkey to evaluate Nitrogen (N) and Phosphorus (P) fertilization on forage quality and plant species composition and to determine their economic impact on animal production. Treatments were 0, 50, 100, 150 and 200 kg ha -1 of N and 0, 50, 100, and 150 kg ha -1 of P fertilizer doses. Nitrogen and Phosphorus fertilization significantly influenced the composition of plants. Botanical composition of experimental fields was recorded as 25 legume, 22 grass and 27 species from other families. The results showed large interaction between P and N due largely to the fact that legume species are relatively abundant fertilization reduced legume proportion; however, P fertilizer increased the proportion of legume in vegetation. Adverse effect of N on growth of legume resulted in significantly crude protein decrease in forage. In both years, overall mean dry matter yield increased with increase in N and P applications. The highest dry matter yield production was 3407 kg ha -1 150 kg ha -1 P and 200 kg ha -1 of N as compared to control treatment which had a 1152 kg ha -1 . Average mean crude protein concentration was 110 g kg -1 for control plots, while it decreased to 106, 102, 104 and 103 g kg -1 for 50, 100, 150 and 200 kg ha -1 N applications, respectively. Crude protein concentrations were significantly enhanced with increasing P fertilizer amounts. Maximum crude protein concentration was 140 g kg -1 and obtained from P150+N0 treatments. The average crude protein yield was 126.7 kg ha -1 in control plots and maximum crude protein yield was 464.1 kg ha -1 from P150+N200 treatment. Overall results indicated that, the most profitable treatment was P150+N200 and average calculated benefit was 644 € per hectare.

Dose response effect of nitrogen and phosphorus on forage quality, yield and economic return of rangelands

The computer-based CERES-maize model for simulating maize growth and development was used to simulate maize yield in a semi-arid region of Harran Plain of Southeastern Turkey in 2005 and 2006. Irrigation water was applied with the water pillow (WP) method at three rates: full (WP1.0); and two deficit irrigation treatments, WP0.75 and WP0.50, which were 75 and 50% of WP1.0, respectively. Measured yields values ranged from 5600 to 9450 kg ha-1 and 5040 to 8565 kg  ha-1 in 2005 and 2006, respectively, whereas measured biomass values for the same years varied from 11020 to 17965 kg ha-1 and 10985 to 17025 kg ha-1. Statistical analysis of the measured yield and biomass values indicated that there was a significant difference between irrigation treatments for both years (P <0.05). Simulated results for 2005 and 2006 varied from 5072 to 8991 kg ha-1 and from 4924 to 8168 kg ha-1, while biomass values for the same years ranged from 10098 and 16906 kg ha-1 and from 10105 to 15985 kg ha-1. For all treatments, yield and biomass were adequately simulated by the model: differences between simulated and measured values were less than 6%. Comparison of the model data with the measured values showed that there was a satisfactory agreement between the measured and simulated values and the model performed well for both, yield and biomass. Overall, it could be suggested that full irrigation is required for optimum yield and biomass and CERES-maize model satisfactorily simulated maize yields and biomass in semi-arid conditions.

	 

	Key words: CERES-maize model, water pillow, maize, water deficit.

/pdf/evaluation-of-ceres-maize-simulation-model-results-with-2utabl9ym2.pdf

Mustafa Okant

Papers

Melatonin-mediated nitric oxide improves tolerance to cadmium toxicity by reducing oxidative stress in wheat plants.

The role of endogenous nitric oxide in melatonin-improved tolerance to lead toxicity in maize plants.

Water pillow irrigation compared to furrow irrigation for soybean production in a semi-arid area

Dose response effect of nitrogen and phosphorus on forage quality, yield and economic return of rangelands

Evaluation of CERES-maize simulation model results with measured data using water pillow irrigation under semi-arid climatic conditions.