Effects of different densities of wild oat (Avena fatua L.) and nitrogen rates on oilseed rape (Brassica napus L.) yield

Kazemeini, Seyed Abdolreza,Naderi, Ruhollah,Aliabadi, Hadis Karimi The Ecological Society of Korea 2013 Journal of Ecology and Environment Vol.36 No.3

A Two-year field experiment was carried out in 2009 and 2010 to evaluate the effects of different densities of wild oat and nitrogen (N) rates on oilseed rape yield and yield components. Experimental design was split plot with three replications. Increased nitrogen rates up to 150 kg N/ha caused an increase in oilseed rape grain yield in weed-free plots (4.26 t/ha; 1t = $10^3kg$), while even at the lowest density of wild oat (15 $plants/m^2$), increasing N fertilizer only up to 50 kg/ha led to a significant increase in grain yield. Wild oat growth was favored by high levels of N. Intraspecific competition reduced biomass, 100-seed weight and number of tillers of wild oat. Both lower N rate and intraspecific competition had negative effect on wild oat growth but the weed was still able to produce a considerable number of tillers and vigorous seeds. It showed that wild oat possess a notable adaptive plasticity and can allocate a greater proportion of its resource toward reproductive organs even under resource shortage conditions and, thus, it may increase the competitive ability of the weed over the crop.Our results suggest that effective weed management should be done to prevent wild oat seed production in crops preceding oilseed rape as well as to control the weed at early season in oilseed rape fields.

Effects of different densities of wild oat (Avena fatua L.) and nitrogen rates on oilseed rape (Brassica napus L.) yield

Seyed Abdolreza Kazemeini,Ruhollah Naderi,Hadis Karimi Aliabadi 한국생태학회 2013 Journal of Ecology and Environment Vol.36 No.3

A Two-year field experiment was carried out in 2009 and 2010 to evaluate the effects of different densities of wild oat and nitrogen (N) rates on oilseed rape yield and yield components. Experimental design was split plot with three replications. Increased nitrogen rates up to 150 kg N/ha caused an increase in oilseed rape grain yield in weed-free plots (4.26 t/ha;1t = 103 kg), while even at the lowest density of wild oat (15 plants/m2), increasing N fertilizer only up to 50 kg/ha led to a significant increase in grain yield. Wild oat growth was favored by high levels of N. Intraspecific competition reduced biomass, 100-seed weight and number of tillers of wild oat. Both lower N rate and intraspecific competition had negative effect on wild oat growth but the weed was still able to produce a considerable number of tillers and vigorous seeds. It showed that wild oat possess a notable adaptive plasticity and can allocate a greater proportion of its resource toward reproductive organs even under resource shortage conditions and, thus, it may increase the competitive ability of the weed over the crop.Our results suggest that effective weed management should be done to prevent wild oat seed production in crops preceding oilseed rape as well as to control the weed at early season in oilseed rape fields.

Effect of plant density ratios and weed control on the performance of maize-bean intercropping

Hossein Sadeghi,Seyed Abdolreza Kazemeini,Mohsen Edalat 한국생태학회 2012 Journal of Ecology and Environment Vol.35 No.4

A 2-year study (2010-2011) was carried out in order to evaluate the effects of bean and maize intercropping. The experiment tested five different cropping systems: sole cropping of each crop, as well as intercropping of maize/bean with the ratios of 1:3 (M1B3), 2:2 (M2B2) and 3:1 (M3B1), each of which took place in the presence of two weed management systems (no weed control and weed eradication through manual removal), in a factorial experiment based on randomized complete block design using three replicates. Tests of homogeneity of variance for combined data over two years showed that data of both years could be analyzed together. The results showed that the effect of intercropping treatments on all measured traits in maize and bean were significantly different. A minimum land equivalent ratio (LER) for maize (0.78)was obtained for M3B1 under conditions of no weed control, while the highest LER (1.03) was observed in M3B1 under weed-free conditions. The highest (0.99) and lowest (0.70) LER values for beans were recorded for M1B3 under weed-free conditions and M3B1 under conditions of no weed control, respectively. M1B3 under weed-free conditions showed the highest total LER (2.02), while M3B1 under conditions of no weed control showed the lowest (1.48). Results of this study indicated that intercropping bean and maize can be an effective method to increase total productivity, and that the M1B3system was the best cropping system for high productivity.

Effect of plant density ratios and weed control on the performance of maize-bean intercropping

Sadeghi, Hossein,Kazemeini, Seyed Abdolreza,Edalat, Mohsen The Ecological Society of Korea 2012 Journal of Ecology and Environment Vol.35 No.4

A 2-year study (2010-2011) was carried out in order to evaluate the effects of bean and maize intercropping. The experiment tested five different cropping systems: sole cropping of each crop, as well as intercropping of maize/bean with the ratios of 1:3 ($M_1B_3$), 2:2 ($M_2B_2$) and 3:1 ($M_3B_1$), each of which took place in the presence of two weed management systems (no weed control and weed eradication through manual removal), in a factorial experiment based on randomized complete block design using three replicates. Tests of homogeneity of variance for combined data over two years showed that data of both years could be analyzed together. The results showed that the effect of intercropping treatments on all measured traits in maize and bean were significantly different. A minimum land equivalent ratio (LER) for maize (0.78) was obtained for $M_3B_1$ under conditions of no weed control, while the highest LER (1.03) was observed in $M_3B_1$ under weed-free conditions. The highest (0.99) and lowest (0.70) LER values for beans were recorded for $M_1B_3$ under weed-free conditions and $M_3B_1$ under conditions of no weed control, respectively. $M_1B_3$ under weed-free conditions showed the highest total LER (2.02), while $M_3B_1$ under conditions of no weed control showed the lowest (1.48). Results of this study indicated that intercropping bean and maize can be an effective method to increase total productivity, and that the $M_1B_3$ system was the best cropping system for high productivity.

Interaction between different nitrogen fertilizer levels and maize-bean intercropping patterns

Sadeghi, Hossein,Kazemeini, Seyed Abdolreza The Ecological Society of Korea 2012 Journal of Ecology and Environment Vol.35 No.4

In order to investigate the effects of different maize-bean intercropping patterns, and of nitrogen fertilizers on morphological and yield related traits, a factorial study based on Randomized Complete Block Design (RCBD) was performed during the 2010 and 2011 growing seasons in a research filed of Shiraz University, Iran. The first factor of the study was seven different ratios of Maize-Bean intercropping system (Maize sole cropping, Bean sole cropping, and intercropping of maize/bean at the ratios of 1/3, 1/1, 2/3, 3/2 and 3/1) and the second factor was three nitrogen (N) fertilizer application levels (0, 100 and 200 kg N/ha). Results showed that with respect to increasing the levels of N fertilizer, the yield of bean sole cropping decreased but the yield of maize sole cropping increased. On the other hand, in intercropping systems with N fertilizer application, the yield of both crops increased. Results of total land equivalent ratio (LER) for both crops showed that the highest LER value under both 100 and 200 kg N/ha application was that of M1B1 (1 seed of maize after 1 seed of bean, consecutively, on a row with same distance). Under no N fertilizer application the highest LER value was that of M2B3 (2 seeds of maize after 3 seeds of bean, consecutively, on a row with same distance). Overall, it can be concluded that M1B1 is the best intercropping pattern in maize-bean intercropping systems and that the application of N fertilizer can be effective within practical settings of intercropping agriculture, resulting in higher yields.