Exogenous application of low and high molecular weight organic acids differentially affected the uptake of cadmium in wheat-rice cropping system in alkaline calcareous soil

Anthropogenic cadmium (Cd) in arable soils is becoming a global concern due to its harmful effects on crop yield and quality. The current study examined the role of exogenously applied low molecular weight organic acids (LMWOAs) including oxalic acid (OxA), tartaric acid (TA) and high molecular weight organic acids (HMWOAs) like citric acid (CA) and humic acid (HA) for the bioavailability of Cd in wheat-rice cropping system. Maximum increase in root dry-weight, shoot dry-weight, and grain/paddy yields was recorded with HA for both crops. The HA significantly decreased AB-DTPA Cd in contaminated soils which remained 41% for wheat and 48% for rice compared with their respective controls. The minimum concentration of Cd in roots, shoots and grain/paddy was observed in HA treatment in both crops. The organic acids significantly increased the growth parameters, photosynthetic activity, and relative leaf moisture contents for both wheat and rice crops compared to that with the contaminated control. Application of OxA and TA increased the bioavailability of Cd in soils and plant tissues while CA and HA decreased the bioavailability of Cd in soils and plants. The highest decrease in Cd uptake, bioaccumulation, translocation factor, immobilization, translocation, harvest, and health risk indices were observed with HA while maximum increase was recorded with OxA for both wheat and rice. The results concluded that use of HMWOAs is effective in soil Cd immobilization being maximum with HA. While LMWOAs can be used for the phytoextraction of Cd in contaminated soils having maximum potential with OxA

Differential Uptake and Translocation of Cadmium and Lead by Quinoa: A Multivariate Comparison of Physiological and Oxidative Stress Responses

Contamination of soils with cadmium (Cd) and lead (Pb) has emerged as a serious environmental issue that reduces crop productivity. However, the metals tolerance and accumulation potential of quinoa (Chenopodium Quinoa Willd) under the combined stress of Cd and Pb has not yet been explored. In the present hydroponic study, the physiological and biochemical characteristics of quinoa exposed to Cd and Pb were explored. Four-week-old plants of quinoa genotype ‘Puno’ were grown under different concentrations of Cd (0, 50 and 100 µM), Pb (0, 250 and 500 µM) alone as well as in combinations. The results showed that with increasing Cd and Pb levels in the nutrient solution, the plant biomass, stomatal conductance and chlorophyll contents were decreased. However, the concurrent application of higher concentrations of Cd (100 µM) and Pb (500 µM) caused even more reduction in the plant biomass (more than 50% than the control) and physiological attributes. The combined application of Pb and Cd caused oxidative stress through an overproduction of H2O2 (10-fold) and TBARS (12.5-fold), leading to decrease in membrane stability (52%). The oxidative stress was alleviated by a 7-fold, 10-fold and 9-fold overactivation of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), respectively. An excessive uptake of Cd resulted in a limited uptake of Pb and K in the roots and shoots of quinoa plants. The Cd and Pb tolerance and uptake potential of Puno showed its ability to stabilize Cd and Pb in co-contaminated soils

Differential Uptake and Translocation of Cadmium and Lead by Quinoa: A Multivariate Comparison of Physiological and Oxidative Stress Responses

Contamination of soils with cadmium (Cd) and lead (Pb) has emerged as a serious environmental issue that reduces crop productivity. However, the metals tolerance and accumulation potential of quinoa (Chenopodium Quinoa Willd) under the combined stress of Cd and Pb has not yet been explored. In the present hydroponic study, the physiological and biochemical characteristics of quinoa exposed to Cd and Pb were explored. Four-week-old plants of quinoa genotype ‘Puno’ were grown under different concentrations of Cd (0, 50 and 100 µM), Pb (0, 250 and 500 µM) alone as well as in combinations. The results showed that with increasing Cd and Pb levels in the nutrient solution, the plant biomass, stomatal conductance and chlorophyll contents were decreased. However, the concurrent application of higher concentrations of Cd (100 µM) and Pb (500 µM) caused even more reduction in the plant biomass (more than 50% than the control) and physiological attributes. The combined application of Pb and Cd caused oxidative stress through an overproduction of H2O2 (10-fold) and TBARS (12.5-fold), leading to decrease in membrane stability (52%). The oxidative stress was alleviated by a 7-fold, 10-fold and 9-fold overactivation of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), respectively. An excessive uptake of Cd resulted in a limited uptake of Pb and K in the roots and shoots of quinoa plants. The Cd and Pb tolerance and uptake potential of Puno showed its ability to stabilize Cd and Pb in co-contaminated soils

Assessing impact of thermal units on growth and development of mustard varieties grown under optimum sown conditions

Thermal unit indices have a strong correlation with the phenology, growth and yield of crops and can be effectively used to select suitable crop cultivars for specific environmental conditions especially temperature. In this study, four mustard varieties (viz., ‘BARI Sharisha-14', ‘BARI Sharisha-15', ‘BARI Sharisha-16' and ‘Tori-7') were grown in two consecutive growing to assess the impact of thermal unit indices on crop growth and development, and to select the suitable variety for better yield under optimum sowing condition. Thermal unit indices viz., growing degree-day (GDD), helio-thermal units (HTU), phenothermal index (PTI) and heat use efficiency (HUE) were estimated from daily temperature and sunshine hours. Role of GDD on different growth indicators and seed yield (SY) were estimated through association and dependence of the traits. Significant variations in studied genotypes were observed for different traits. Among the studied varieties, ‘BARI Sharisha-16' produced higher dry matter and seed yields (1.82 t ha-1) while accumulated maximum GDD at different growth stages. A strong positive association was obtained between GDD and the studied traits. Thermal unit indices had a strong influence in attaining different phenophases and other growth indicators. Therefore, results suggest that those indices could be used for growth prediction; further ‘BARI Sharisha-16' is expected to use heat energy more efficiently for increasing the seed yields which indicated that the crop can perform better under global warming scenarios. © 2019, Association of Agrometeorologists. All rights reserved

Systematic analysis of tup1 and cyc8 mutants reveals distinct roles for TUP1 and CYC8 and offers new insight into the regulation of gene transcription by the yeast Tup1-Cyc8 complex.

The Tup1-Cyc8 complex in Saccharomyces cerevisiae was one of the first global co-repressors of gene transcription discovered. However, despite years of study, a full understanding of the contribution of Tup1p and Cyc8p to complex function is lacking. We examined TUP1 and CYC8 single and double deletion mutants and show that CYC8 represses more genes than TUP1, and that there are genes subject to (i) unique repression by TUP1 or CYC8, (ii) redundant repression by TUP1 and CYC8, and (iii) there are genes at which de-repression in a cyc8 mutant is dependent upon TUP1, and vice-versa. We also reveal that Tup1p and Cyc8p can make distinct contributions to commonly repressed genes most likely via specific interactions with different histone deacetylases. Furthermore, we show that Tup1p and Cyc8p can be found independently of each other to negatively regulate gene transcription and can persist at active genes to negatively regulate on-going transcription. Together, these data suggest that Tup1p and Cyc8p can associate with active and inactive genes to mediate distinct negative and positive regulatory roles when functioning within, and possibly out with the complex

Yield of wheat is increased through improving the chemical properties, nutrient availability and water productivity of salt affected soils in the north delta of Egypt

The lysimeter experiment was carried out twice in consecutive two years (2014-15 and 2015-16) at Sakha Agricultural Research Station, Kafrelsheikh, Egypt to study the effect of three irrigation levels water (i.e., 100, 110 and 120% field capacity (FC), two rates of gypsum (G) (i.e., 50 and 100% G) and three sources of nitrogen (90 kg nitrogen (N), 10 t compost (C) and 7.5 t C + 45 kg N (CN) fed-1 (fed = 4200 m2)) on grain yield of wheat, water relations and soil chemical properties. Water consumptive use (WCU) was markedly increased due to the increase of the level of irrigation, rate of gypsum (G) and CN source (7.5 t C + 45 kg N fed-1). Irrigation with water amount equal to 120% FC recorded the highest values of WCU 1433 and 1570 m3fed-1 in both seasons. Water productivity (kg grain m-3 water) for either water application (WA) in both seasons or WCU in the second season was decreased by increasing level of irrigation from 100 to 120% FC in the second season, while the inverse was true for WCU in the first season. The highest mean values of water productivity for WCU 1.816 and 1.791 kg m-3 were obtained with the irrigation level of 120% FC in the first season and 100% FC in the second season, respectively. Gypsum rate and N source have an effect on the productivity of irrigation water (WP) for WA and WCU, where the highest mean values for both the two irrigations efficiency were recorded under 100% G requirements and CN (7.5 t C + 45 kg N fed-1). The interaction of 110% FC × 100% G × 7.5 t C + 45 kg N fed-1 produced the highest values of WP for WA (1.245 and 1.374 kg grain m-3 WA) in both seasons. Grain yield fedd.-1 was increased significantly with the irrigation level from 100 to 120% FC in both seasons, G rate and CN source. Grain yield (GY) did not differ significantly due to the levels of irrigation water between 120 and 110% FC in both years. Application of 100% G and 7.5 t C + 45 kg N fed-1 at any irrigation level were among those treatments having high GY, being insignificant. The mean values of electrical conductivity (acidity; ECe) and soil sodicity (SARe) were affected by irrigation treatments, G rates and nitrogen sources. A stronger reduction in soil ECe and SARe were recorded under the irrigation level of 120%FC, 100% G and 10 t compost in both seasons. While the soils ECe and SARe were increased by application of chemical N fertilizer alone or with compost. Therefore, it can be concluded that irrigation with water amount equal to 110 or 120% FC, 100% G requirements and 7.5 t C and 45 kg N fed-1 was the best treatment for getting high GY, improving the soil chemical properties, nutrients availability and increasing the water productivity of salt-affected soil in North Delta of Egypt. © 2019, ALÖKI Kft., Budapest, Hungary

Optimizing Nitrogen Application in Root Vegetables from Their Growth, Biochemical and Antioxidant Response to Urea Fertilizer

Nitrogen is one of the most influencing inorganic nutrients for improved plant growth and yield in crops. However, excessive fertilizer application may have adverse impacts on the environment. Therefore, we strive to investigate in this work by examining the impact of different nitrogen (N) doses in the form of urea (46% N) on the growth, yield, photosynthetic pigment content, nitrate reductase activity, carbohydrate content, protein content, and antioxidant enzyme activity of the carrot and beetroot. A pot experiment was conducted under natural conditions with four nitrogen levels as basal treatment (Control = Nil N, U50 = 145.57 mg/kg N; U100 = 291.14 mg/kg N; U150 = 436.71 mg/kg N; U200 = 582.28 mg/kg N). Results found that U150 (436.71 mg/kg N) is the optimum N fertilizer dose at which significant (p ≤ 0.05) improvements in all the growth, yield and biochemical attributes of carrot and beetroot were observed. However, the further increment in N doses did not affect the observed parameters and, therefore, excessive N level was observed beyond U150 = 436.71 mg/kg N. The principal component analysis presented significant correlations among the various parameters observed. Two principal components account for a total of 98.86% variance (PC1 =  92.96%; PC2 =  5.90%) in carrot and 99.2% variance (PC1 = 92.64; PC = 6.56) in beetroot of the overall data variability in plants supplemented with different N treatments

Soaking Maize Seeds in Zeatin-Type Cytokinin Biostimulators Improves Salt Tolerance by Enhancing the Antioxidant System and Photosynthetic Efficiency

There is an urgent need for innovative strategies to raise the performance of environmentally stressed plants. The seeds of single-cross yellow Zea mays (L.) hybrid Giza-168 were soaked in Cis-(c-Z-Ck) or trans-zeatin-type cytokinin (t-Z-Ck) solutions at a concentration of 50 or 40 µM, respectively. Salinity stress was imposed at 0, 75 or 150 mM NaCl in the Hoagland nutrient solution (full strength) used for irrigation. The total carotenoids content was negatively affected by only 150 mM NaCl, while both 75 and 150 mM NaCl negatively affected the growth and yield components, relative water content, membrane stability index, photochemical activity, gas exchange, K+ and chlorophyll contents, K+/Na+ ratio, and photosynthetic efficiency. However, all of these traits were significantly improved by c-Z-Ck pretreatment and further enhanced by t-Z-Ck pretreatment compared with the corresponding controls. Furthermore, the contents of proline, soluble sugars, ascorbate, and glutathione, as well as enzymatic antioxidant activities, were significantly elevated by both salt stress concentrations and increased more by both biostimulators compared to the control. Compared to c-Z-Ck, t-Z-Ck was superior in mitigating the harmful effects of the high H2O2 levels caused by salt stress on the levels of malondialdehyde and ion leakage compared to the control. Under normal or stress conditions, t-Z-Ck pretreatment was better than c-Z-Ck pretreatment, while both positively affected maize hormonal contents. As a result, t-Z-Ck is recommended to enhance the growth and productivity of maize plants by suppressing the effects of oxidative stress caused by saline water irrigation

Flowering Synchronization in Hybrid Rice Parental Lines at Different Sowing Dates

Hybrid seed set on the female line depends primarily on its flowering synchronization with the restorer line (R), therefore, the sowing of male and female lines must be planned properly to achieve this. Field experiments on different sowing dates (May 1st, May 15th, and May 30th) of R lines (Giza 178R, Giza 179R, and Giza 181R) and cytoplasmic male sterile (CMS) lines (IR69625A, IR70368A, IR58025A, K17A, and G46A) were carried out at the farm of Sakha Agricultural Research Station, Kafr El-Sheikh, Egypt during 2019 and 2020 to study the effect of sowing dates on flowering synchronization in hybrid rice. The results indicated that the synchronization of flowering between CMS lines and R lines has highly significant effects on the days to 50% heading, number of leaves, effective accumulated temperature (EAT), plant height, panicle exertion percentage, panicle length, number of fertile panicles, panicle weight, seed set percentage, harvest index and seed yield of hybrid rice. The highest seed yield (1.72 and 1.41 t ha−1, respectively in 2019 and 2020) was recorded from the sowing date May 1st and the hybrid combination of Giza 178R × IR58025A (2.06 and 2.12 t ha−1 in 2019 and 2020, respectively). The grain yield had a significant and highly significant positive correlation with the plant height (cm), panicle exertion percentage, panicle length, number of panicles plant−1, panicle weight, seed set percentage, and harvest index. In Egypt, May 1st is the best time for the synchronization of hybrid rice lines and a combination of Giza 178R × IR58025A may be recommended for better performance