davoud davani; majid nabipour; habibollah roshanfekr
Abstract
Introduction: Maize (Zea mays L.) which belongs to the Poaceae family is the third important cereal crop of the world after wheat and rice. Salinity is one of the major environmental factors limiting plant growth and productivity. Maize is sensitive to salinity. Planting method is a crucial factor for ...
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Introduction: Maize (Zea mays L.) which belongs to the Poaceae family is the third important cereal crop of the world after wheat and rice. Salinity is one of the major environmental factors limiting plant growth and productivity. Maize is sensitive to salinity. Planting method is a crucial factor for improving crop yield. Planting methods in saline and non-saline conditions are different. Kinetin is one of the cytokinins known to significantly improve the growth of crop plants grown under salinity. Indole acetic acid (IAA) is also known to play a significant role in plant tolerance to salt stress. However, little information appears to be available on the relationship between salinity tolerance and auxin or cytokinin levels in plants. In this respect, the objective of this study was to study the effects of foliar application of cytokinin and auxin hormones on distribution and accumulation of chlorine and some macro elements in different parts of maize in salinity conditions.
Materials and Methods: The experiment was carried out at Bushehr Agricultural and Natural Resources Research and Education Center, Dashtestan station with 29° 16´ E latitude and 51° 31´ N, longitude and 70 m above the see surface during the 2014 growing season. Dashtestan region is a warm-arid region with 250 mm precipitation per year. The field plowed inApril 2014 and then prepared and sowed inAugust 2014. There were five rows with 75 cm distance. The experiment was conducted as a split-plot design based on complete randomized blocks with three replications. Planting pattern (ridge planting, double rows of planting on a ridge in zigzag form and furrow planting) as the main factor and use of hormone (not consumption (control), application of cytokinin hormone in the time of V8-V10 and application of auxin hormone at the silking stage) was considered as the sub-factor. Cytokinin (Benzyl Adenine, Merck) and Auxin (Indole-3-Butiric Acid, Merck) were sprayed on the entire plant in the evening with concentration of 50 and 10 g. l-1, respectively. All traits measured on 10 randomly selected plants of each plot. Data analyzed using the SAS (Ver.9.1) and comparing of the means was conducted using Duncan’s multiple range test.
Results and Discussion: The measured salinity of soil at a depth of 0 to 30 cm in different locations of planting patterns and in different time period showed that in different planting patterns because salt movement by capillary ascent and its accumulation in the ridges, salinity center stack was the highest and the lowest salinity belonged to the furrow planting. The highest Potassium (K+) and Calcium (Ca2+) ions were obtained with pattern of furrow planting, while the highest sodium ions (Na+), Chlorine ions (Cl-) and Na+/K+ were devoted to the pattern of conventional planting (ridge planting). Foliar application of benzyladenine (BA) and indole-3-butyric acid (IBA) sodium ions (Na+) and Na+/K+. The results showed that in all three planting pattern the most sodium leaf was obtained without the use of hormone auxin, but the lowest amount of sodium leaf was observed with auxin treatment. In each pattern, use of hormone leading to increased potassium of shoot, but the largest increase was cytokinin hormone, of course, the greatest increase was achieved by application of cytokinin hormone. In furrow planting use of hormone reduced the amount of leaf chlorine so that most leaf chlorine was obtained without the use of hormones. While, use of cytokinin and auxin hormones reduced the amount of leaf chlorine by 6.86 and 21.24 percent, respectively. Use of hormone in all planting methods reduced the amount of shoot chlorine but the greatest reduction was achieved by application of cytokinin hormone.
Conclusions: In general, it can be concluded that increasing concentrations of sodium, magnesium and chlorine in leaves and shoots in row planting compared to planting two rows and furrow planting could be related to higher concentrations of these elements in the soil and in the location of the plant and as a result decrease of plant growth and therefore higher concentration of elements in various parts of the plant in the row planting. It is concluded that use of cytokinin and auxin especially in the furrow planting reduced the concentration of sodium, chloride and sodium to potassium ratio and increased plant potassium and calcium concentration.
R. Moazenzadeh
Abstract
Introduction: In two last decades, greenhouse cultivation of different plants has developed among Iranian farmers, approximately 45 percent of national greenhouse cultures consisting of cucumber, tomato and pepper. As huge amounts of agricultural water in Iran are extracted from groundwater resources ...
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Introduction: In two last decades, greenhouse cultivation of different plants has developed among Iranian farmers, approximately 45 percent of national greenhouse cultures consisting of cucumber, tomato and pepper. As huge amounts of agricultural water in Iran are extracted from groundwater resources and a large number of Iranian plains are in critical conditions, and because irrigation is the major consumer of water (95 percent), it must be performed in a scientific manner. One approach to this is to obtain the knowledge of the consumptive use of major crops which is named evapotranspiration (ETc).
Materials and Methods: This research was carried out in a north-south greenhouse belonging to Plant Protection Research Institute, located on northern Tehran, Iran, for estimating greenhouse cucumber evapotranspiration. Trickle irrigation method was used, and meteorological data such as temperature, humidity and solar radiation were measured daily. Physical and chemical measurements were conducted and electric conductivity (EC) and pH values of 3.42 dsm-1 and 7.19, respectively, were recorded. Soil texture and bulk density were measured as to be sandy loam and 1.4 gr cm-3, respectively. In order to measure the actual evapotranspiration, cucumber seeds were also cultured in six similar microlysimeters and irrigation of each microlysimeter was based on FC moisture. If any drained water was available, it was measured. Finally, with measured meteorological characteristics in greenhouse which are suggested to have an effect on ET and were measurable, the best multiple linear regression and artificial neural network were established. The average data from three microlysimeters were used for calibration and that from three other microlysimeters were used for validation set.
Results and Discussion: In the former case, when we used one multiple linear regression with measurable meteorological variables inside the greenhouse to predict cucumber ET for the entire growth period, high and considerable amounts of error occurred, as the difference between measured and predicted values of ET is approximately 2.86 mm day-1 which is noticeable. Overestimation of the cucumber ET in the first and last stages which will result in decreasing water use efficiency and underestimation in blooming and yielding fruit stages, when cucumber is more susceptible to water stress, are the other disadvantages of using one equation for the entire growth period to describe and predict cucumber ET. In contrast, when we divided growth period into four steps, the MLR method’s performance in prediction of ET was improved and the difference mentioned above between measured and predicted values of ET (2.86 mm day-1) decreased to about 1.32 mm day-1. The results showed that measured and predicted values of ET ranged from (0.08 to 4.75) and (0.13 to 4.25) when the whole growth period is considered as one step, respectively. These mentioned values were obtained (0.08 to 1.5) and (0.13 to 1.75); (0.71 to 2.64) and (1.31 to 4.25); (2.18 to 4.75) and (1.69 to 4.13); (1.32 to 2.61) and (2.66 to 3.74) for each of growth period stages, respectively. Also the value of total ET for the entire growth period is measured 273.45 mm and predicted 275.7 and 275.59 mm, when the whole growth period is considered as one step or divided into four stages, respectively. Although dividing the growth period improved ET prediction, the results in the first and especially the third stage are still discussable. Therefore, as with MLR method, the capability of ANN technique was investigated in prediction of cucumber ET. Comparison of measured and predicted values of ET confirms that ANN has better performance than MLR, even when growth period is divided.
Conclusion: Determining cucumber evapotranspiration in the greenhouse was the main objective of this study. For this purpose we used Multiple Linear Regression (MLR) and Artificial Neural Network (ANN) techniques. In MLR, first we used one equation for the entire growth period. The results showed that this single equation is not able to simulate actual ET of cucumber. To overcome this problem, we divided the growth period into four stages and derived a separate equation for each stage. The results showed that this procedure improves prediction of cucumber ET, especially in the second and last stages of growth period. Statistical indices such as RMSE, Ens, PBIAS and PSR, t-statistical results, measured versus predicted ET values, and predicted values of ET in the growth period indicate that ANN technique is not only reliable, but also easier than the MLR technique.
