Journal of Research on Crop Ecophysiology
Volume:9 Issue: 1, Winter 2014

Continuous desertification of arable lands due to urbanization, global warming, and shortage of water mandates use of low quality/saline water for irrigation, especially in the regions experiencing water shortage. Using low quality/saline water for irrigation imposes more stress on plants which are already under stress in these regions characterized with saline soils and shortage of water. Thus, there is an urgent need for finding salt/drought tolerant plant species to survive/sustain under such stressful conditions. Since the native plants are already growing under such conditions and are adapted to these stresses, they are the best and the most suitable candidates to be manipulated for use under these stressful conditions. If stress tolerant species/genotypes of these native plants are successfully identified, there would be a substantial savings in cultural practices and inputs in using them by the growers and will result in substantial savings in the currencies of the countries. My investigations at the University of Arizona on saltgrass (Distichlis spicata L.), a euhalophytic plant species, have indicated that this plant has an excellent drought and salinity tolerance with a great potential to be used under harsh and stressful environmental conditions. This grass has multi usages, including animal feed, soil conservation, saline soils reclamation, and combating desertification processes. The objectives of this study were to find the most salt tolerant of various saltgrass genotypes for use in arid and semi-arid regions for sustainable agriculture and biologically reclaiming saline soils. Twelve saltgrass clones were studied in a greenhouse, using the hydroponics technique to evaluate their growth responses in terms of shoot and root lengths and DM weights, and general grass quality under salt stress conditions. Grasses were grown vegetatively in Hoagland solution for 90 days prior to exposure to salt stress. Then, 4 treatments [EC of 6 (control), 20, 34, and 48 dSm-1 salinity stress] were replicated 3 times in a RCB design experiment. Grasses were grown under these conditions for 10 weeks. During this period, shoots were clipped bi-weekly, clippings were oven dried at 65o C and DM weights were recorded, and shoot and root lengths were also measured. At the last harvest, roots were also harvested, oven dried, and DM weights were determined. General grass quality was weekly evaluated and recorded. Although, all the grasses showed a high level of salinity tolerance, there was a linear reduction in their growth responses as salinity level increased. However, there was a wide range of variations observed in salt tolerance of these saltgrass clones. The superior stress tolerant genotypes were identified which could be recommended for sustainable production under arid regions and combating desertification. This grass proved to not only have a satisfactory growth under the harsh desert conditions, but also to substantially reduce salinity level of the rhizosphere, which indicates that saltgrass can effectively be used for biological salinity control or reclamation of desert saline soils and combating desertification processes.

This experiment was conducted to evaluate the effects of NaCl priming on growth traits and some biochemical attributes of safflower (Carthamus tinctorius L. cv Safola) in salinity conditions. Seeds of safflower were primed with NaCl (5 g L-1) for 12 h in 23 °C. Primed (P) and non primed (NP) seeds were directly sown in the field. Experiments were conducted using various water concentrations induced by NaCl (0, 3, 6, 9 and 12 g L-1) in salinity experiment. Results showed that growth (plant height, fresh and dry weight) and biochemical (chlorophyll, proline and proteins content) of plants derived from primed seeds were greater of about 15 to 30% than that of plants derived from non primed seeds. It seems that salinity tolerance in priming resulted plants was due to higher potential of these plants to accumulate more biochemical attributes (more chlorophylles, proline and proteins in primed plants than controls ones).

In order to study the effect of increasing density of red root pigweed on leaf area index (LAI) of corn, and also on pigweed in different levels of nitrogen application, two field experiments were conducted during 2010 and 2011 crop years in Research Field of Azad Islamic University of Astara (north west of Gilan, Iran). The experimental design in each year was split plot based on randomized complete block design with 3 replications. The main factor was nitrogen amount in four different levels including zero (control), 100 (recommended nitrogen amount in the region), 160 and 220 kg nitrogen per hectare. The secondary factor was intensity of red root pigweed in four levels including zero (corn pure culture), 5, 10 and 20 plants per square meter. Results demonstrated that 25-35 days after growth of two plants, leaf area index of corn crop was more than red root pigweed in all levels of nitrogen and all intensities of pigweed. After this period, leaf area index increased in pigweed more than corn. The highest leaf area index of corn was observed in nitrogen application level of 160 kg per hectare and increasing nitrogen level and pigweed intensity resulted its decrease and increase in the corn and pigweed, respectively. The most grain yield of corn was acquired using 160 and 220 kg nitrogen per hectare, respectively with zero weed intensity and their values were 15.9 and 12.3 tons per hectare, respectively that their values decreased severely by increasing weed intensity in the farm.            21

The sunflower oilseed and confectionaries types (Helianthus annuus L.) are definitely different in nutritional responses. This study attempted to evaluate differences in the expression levels of phosphorus and zinc arising from different fertilization treatments. The field experiment was conducted out at Agricultural Research Centre, in Islamic Azad University Arak, Iran, during 2011. Experiment was laid in split plot in randomized complete block design with 3 replications. Phosphorus treatments were in main plots and zinc in sub plots. Phosphorus levels were including 350, 175, 175 kg/ha triple super phosphate plus 100 g/ha phosphorus solublizing bacteria (PSB) and PSB alone and zinc levels were 0, 25 kg/ha soil application zinc sulphate, 25 kg/ha soil application of zinc sulphate plus 10% soluble zinc foliar application and soluble zinc foliar application alone. The results of roots quality in two sunflowers types showed P concentration in confectionary sunflower roots in all zinc levels was significantly higher. Use of 175 kg/ha triple super phosphate plus phosphorus solubilising bacteria (P < /font>3( or utilization of pure PSB (P < /font>4) in test plots was one of the main cause to increase phosphorus concentration in sunflower roots in check plots for zinc (Z1). Leaf phosphorus content was sharply higher in confectionary sunflower when fertilized with phosphorus and zinc mixture. High P application (P < sub>1) was the main cause for slow reduction in leaf zinc concentration for oilseed from 40 to 20 mg/kg. However, PSB and chemical phosphate use (P < sub>3) and PSB alone (P < sub>4) caused the leaf zinc content to increase significantly by foliar zinc application (Z4). Furthermore, the most zinc accumulation was detected in confectionary sunflower seeds by 55 mg/kg in PSB and chemical phosphate use treatment plus foliar soluble zinc application (P < sub>3Z4).

Water stress can affect germination by decreasing the percentage of germination. A study was undertaken to evaluate the influence of different osmotic potentials (MPa) on proline content and percentage seed germination of corn. The experiment was conducted in factorial with a randomized complete block design (RCBD) with three replications. Seeds of two open pollinated varieties (Masmadu and Thai super sweet) and three Hybrids (968,969 and 926) sweet corn were germinated at 0, -0.2, -0.5, -0.7, -1.2 and -1.4 MPa osmotic potentials. Results showed the percentage of germination and coefficient of velocity decreased with decrease in osmotic potential while proline content and mean germination time increased. Polyethylene glycol increased root length and length per volume at low osmotic potential (-0.2 MPa) but decreased at more than -0.7 MPa. Seedling proline content appears not to be related to percentage germination but appears to be related to the decline in osmotic potential in germination media. Seed germination test at -0.7 to -1.2 MPa has the potential to be used as a vigor test in sweet corn.

Bangladesh is a disaster prone developing country, where people's staple food is rice. Numerous natural calamities visits here round the year, and impeded the crusade of development. This study was designed to evaluate the impact of climate change on supply and demand, as well as predict the future scenario of rice in Bangladesh. The findings of the study revealed that although, production of local varieties in aus, aman and boro season is decreasing owing to lower yield and shrinking of planted area aggregated production of rice is increasing due to higher production of modern varieties. As the total rice production increases quantity of imports is decreased in one hand and on the other hand, the bulk of stock is increased gradually. Higher level of per capita income growth rate leads to the diversification of consumers' food habit. Along with negative income elasticity of demand, decreased per capita consumption of rice including other food items in dietary system. However, total demand of rice will increase eventually as the population increasing. The enumerated results of simulation based on past trend and performance of data was very precise and reliable, and could be useful for future policy implications.