The Effect of biological and nitrogen chemical fertilizers on yield and yield component of bean (Phaseolus vulgaris L.) under water stress conditions

In recent years, by minimizing the use of chemical fertilizers and replacing them with biological fertilizers has become important as one of the key principles of sustainable agriculture. Common bean (Phaseolus vulgaris L.) is the world’s most important food legume. This staple considered as a nearly perfect food mainly because of its high protein content and abundant fiber, complex carbohydrates, and other daily food needs such as vitamins (folate) and minerals (Cu, Ca, Fe, Mg, Mn, and Zn). Water used in agricultural production as one of the most important environmental factors affecting plant growth and development, especially in arid and semi-arid climatic conditions of Iran is of special importance. Since biological facility for production increase in agriculture is use of terrestrial useful living tiny, that cause is becoming plant yield and growth increase.

In order to study the effect of plant growth promoting Rhizobacteria and nitrogen chemical fertilizer on yield and yield component of bean (Phaseolus vulgaris L.) under water stress conditions, a split-plot design based on RCBD with three replications was conducted at Agricultural Research Station, College of Agriculture, Ferdowsi University of Mashhad, Iran in 2015. Three levels of irrigation (to supply of 100, 75, and 50 percent water requirement) were assigned to main plots and different types of biofertilizers (1- Nitroxin, containing Azotobacter sp. & Azospirillum sp. as inoculation seed, 2- Biophosphor, containing Phosphate-solubilizing bacteria Bacillus sp. & Pseudomonas sp.) as inoculation seed, 3- Nitrogen chemical fertilizer (100 kg.ha-1 urea form), and 4- Control (no fertilizer) were assigned to sub plots. Irrigation levels according to irrigation requirements in each irrigation period were carried out by water meter device. The growth index of LAI (leaf area index) was determined randomly from 5 competing plants regarding the marginal effects from 1 real completed leaf stage to the end of the growing season (every 7 days; 12 steps). LAI index was calculated using equation (1). Leaf area was calculated by Leaf Area Meter device (Delta T, UK). At the end of growing season, yield and yield component were determined regarding the marginal effects from 5 m2 surfaces. Data analysis of variance and draw charts were done by Minitab Ver. 16, Slide Write Ver. 2, and Excel 2010 softwares. At the end, Means comparing did by Duncan's test at probability 5 percent.LAI= (1/GA) [(LA2+LA1)/2] (Equation 1)Where GA is ground area (m2), LA is leaf area (m2).

According to the result, the effect of fertilizers was significant (P≤0.05) on grain yield, and number of pod per plant, and was very significant (P≤0.01) on number of seeds per pod, and 100 seed weight. Among these fertilizers, Nitroxin fertilizer had the highest effect on traits and was increased these compare to control 92.4, 101.7, 47.3 and 38.7 percent, respectively. Also the effect of irrigation levels on all of traits was very significant (P≤0.01). So that the lowest of traits were observed in 50 percent water requirement of bean and compare to 100 percent water requirement were decreased 68.1, 35.8, 56.3 and 38.1 percent, respectively. Interaction of fertilizer and irrigation was significant (P≤0.05) only on dry matter yield of bean, so that the highest and the lowest of dry matter yield were obtained from Nitroxin+100% water requirement (7741 kg.ha-1) and Control+50% water requirement (880 kg.ha-1), respectively. In general, the results of this experiment declared that there was no significant difference between using of Biophosphor and nitrogen chemical fertilizer concerning the effect on bean traits including: seed yield, pod no. per plant, seed no. per pod, 100 seeds weight.

The results showed that could be possible to produce the healthy production of bean, moreover, attain the optimum yield as equal as to conventional systems.