جستجوی مقالات مرتبط با کلیدواژه « آمونیوم » در نشریات گروه « زراعت »

Soil salinity and alkalinity seriously affect about 932 million hectares of land globally, reducing productivity in about 100 million hectares in Asia. Plants in alkaline soil must cope with physiological drought and ion toxicity, and also maintain intracellular ion balance and regulate pH outside the roots. Alkaline stress result into decrease in chlorophyll concentration, stomatal conductance and transpiration rate and inhibite the growth of plant. Nitrogen sources affect the pH of nutrition solution, which can affect plant growth, so nitrate increases the pH of nutrient solution while ammonium decreases pH of nutrition solution.

In order to evaluate the effect of nitrogen sources on vegetative growth, physiological and chlorophyll fluorescence of white and purple garlic genotypes under sodium bicarbonate stress, an experiment was carried out as factorial base on completely randomize desigen with three factors; sodium bicarbonate at three levels (0, 10 and 20 mM), nitrogen sources (5 mM ammonium sulfate, ammonium nitrate and calcium nitrate in nutrient soulotion) and genotypes (white and purple) with three replications in 2017 in Greenhouse of Faculty of a Agriculture, University of  Vali-e-asr Rafsanjan.

The results showed that shoot and root fresh and dry weight decreased by increasing sodium bicarbonate from 10 mM to 20 mM in nutrient solution and application of ammonium nitrate and ammonium sulfate sources decreased the negative effect of sodium bicarbonate on shoot and root fresh and dry weights. Among nitrogen sources, ammonium sulfate produced the highest soluble sugar content in both garlic genotypes. Proline content was enhanced by increasing sodium bicarbonate concentration in nutrient solution. The highest photosynthetic pigments were absorbed in plant that nourished by ammonium nitrate and ammonium sulfate, respectively. The sources of nitrogen, sodium bicarbonate and their interaction had no significant effect on chlorophyll fluorescence parameters, but genotype had significant effect on these traits.

According to the results of this experiment, the use of ammonium sulfate and ammonium nitrate sources has a better performance on growth and yield of garlic under bicarbonate stress conditions.

Two important factors in producing forage maize (Zea mays L.) are weed control and nitrogen fertilizer management. Low maize yields are typically attributed to low corn growth rate at the beginning of the growing season, wide spacing of plant rows and rapid establishment of weeds. Weeds are a major challenge to row crops and research has usually emphasized on the integrated weed management using chemicals and mechanical control (Chauhan, 2013). In modern agriculture, weed control is primarily done with herbicides due to the effectiveness and ease of use. However, environmental concerns about pollution of groundwater and surface water, have led researchers to focus on integrated weed management and reduced herbicide consumption. On the other, selection of nitrogen fertilizer source may be an important component of weed management. Some studies have investigated nitrogen fertilizer management in order to integrated weed management. The present study was carried out to investigate the effect of chemical control and mechanical + chemical control of weeds and different sources of nitrogen fertilizer on weeds control and quantitative and qualitative characteristics of forage maize.

This experiment was conducted with a factorial arrangement based on randomized complete block design with three replications at the experimental station of Ferdowsi University of Mashhad during the growing season of 2015 -2016. The treatments were control methods of weeds including chemical control, integrated control (mechanical+chemical) and weedy control, and the sources of nitrogen fertilizers including urea (U), ammonium sulfate (AS), calcium nitrate (CN), ammonium nitrate phosphate (ANP) and no fertilizer (NF). In this study, Kjeldahl method was used to measure nitrogen content of the forage. Crude protein (CP) of forage maize was calculated using the following equation (1). Measurements of acid detergent fiber (ADF) and neutral detergent fiber (NDF) was done based on Van Soest method (1967). The equation (2), proposed by Oddy et al (1983) was used to determine digestible dry matter (DMD). Equation 1: 6.25 × N (%) = CP (%) Equation 2: DMD (%) =83.58 – 0.82 ×ADF(%) + 2.262 × N(%).

The integrated control of weeds reduced dry matter of weeds compared to chemical control by 68% and 57% in the first and second year of the experiment, respectively (50 days after corn planting), leading to increased dry matter yield of maize by 17% and 14%, respectively. Furthermore, in the integrated control, herbicide consumption decreased 25% compared to chemical control. However chemical control of weeds reduced dry matter of weed compared to weedy control by 71% and 79% in the first and second year, respectively. The greatest dry matter yield (DM-Y), dry matter digestible yield (DMD-Y) and crude protein yield (CP-Y) were observed with the integrated control and ANP or AS application (there were no significant differences between ANP and AS fertilizers), while the lowest DM-Y, DMD-Y and CP-Y were obtained with weedy control (there were no significant differences between fertilizers treatment).

In the integrated control with proper implementation to reduce weed dry matter, not only did increased quantitative and qualitative yield of forage but also herbicide consumption decreased 25% compared to chemical control. Reducing herbicide consumption through integrated weed management will preserve the environment, improve human health and increase product quality and quantity. On the other hand, it seems that (ANP and AS) as nitrogen fertilizer sources are more effective in terms of increasing maize production compared to other nitrogen sources. It can be suggested, using ANP fertilizer that contains both nitrogen forms (nitrate and ammonium) leads to increasing maize yield. Also, assimilation of ammonium requires the low energy and occurs faster than nitrate in plants. This energy savings may lead to greater dry weight production for plants with an ammonium diet. In addition, the sulfur in AS fertilizer as an essential element for plants may improved plant growth and metabolism.