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Effects of wild mustard (Sinapis arvensis L.) and wild oat (Avena ludoviciana L.) densities on grain yield and yield components of wheat in response to various levels of nitrogen.

Introduction

Due to increasing world population, food security becomes a major concern to human beings and the last word in modern agriculture is yield maximization. This approach is almost based on the application of high level pesticides and fertilizers [2]. There are many factors responsible for low yield. Weed infestation is one of the major causes of low crop yield. Weeds reduce the quantity and quality of the crop yield and increase the cost of cultivation. To increase crop production controlling of the weeds is major aspect. Giambalvo et al. [5], Mennan [12] and Guillen-Portal et al. [6] revealed that inetrespecific competition of weeds with wheat had decreased the biomass, grain yield, number of spikes per meter square, number of grains per spike and thousand grain weight.

Fertilizers increase the cost of crop production, hence their efficient utilization is an important factor in agriculture. Weeds like crops respond positively to increased soil fertility. In worst scenario, crop yields may actually decrease as fertilizer's level increase, if weeds have access to the added fertilizers [3]. Di Tomaso [4] reported that weeds accumulate higher level of nitrogen, phosphorus, potassium, calcium and magnesium than crops and reduce soil nutrient level faster, thereby decrease the crop yield. Barker et al. [1] reported that when velvetleaf, Abutilon theophrasti Medic., emergence early or at the same time of corn, increasing nitrogen level may increase corn yield loss due to valvetlaef competition.

Blackshaw et al. [3] indicated that regarding weed-crop species and density, the competitive ability of weeds can be increased more than crop by application of N. In their experiment adding nitrogen increased the biomass of many weed species like wild mustard, Sinapis arevensis L., and redroot pigweed, Amaranthus retroflexus L., more than wheat, Triticum aestivum L. and canola, Brassica napus. Iqbal and Wright [10] investigated the effect of nitrogen levels (20 and 120 kg N [ha.sup.-1]) on competition between spring wheat and three weed species (Phalaris minor Retz, Chenopodium album L. and Sinapis arvensis L.). Their results indicated that nitrogen supply had affected the relative competitive abilities of weeds and wheat. Sinapis arvensis was more competitive than wheat while P. minor was less competitive than wheat at high level of N. Ross and Van Aker [16] evaluated the effect of nitrogen fertilizer on wild oat, Avena fatua L., interference in spring wheat. They observed that competitive ability of wild oat with wheat in the presence of nitrogen fertilizer significantly increased.

Wild mustard, Sinapis arvensis, and wild oat, Avena ludoviciana, are two of the most dominant weedy species in the wheat fields of Khuzestan province, Iran [11,8]. Studies on effects of nutrients particularly nitrogen at various levels on crop-weed growth and competition are important. Therefore present study was conducted to evaluate the effects of wild mustard and wild oat on yield and yield components of wheat under varying levels of nitrogen addition.

Materials And Methods

Field experiments were conducted at Research Field of Islamic Azad University, Ahvaz, Iran in 2007-8 and 2008-9 cropping season. Soil type was silty clay loam with a pH of 7.5 to 7.6. The experiments were designed as a randomized complete block with a split-factorial arrangement in additive series with three replications. Treatment included three nitrogen levels (90, 150 and 210 kg/ha), four densities of wild mustard (0, 5, 10 and 15 plants/[m.sup.2]) and four densities of wild oat (0, 25, 50 and 75 plants/[m.sup.2]). Nitrogen levels were maintained in main plots and weed densities were maintained into sub-plots. Complete dose of phosphorous (100 kg/ha [P.sub.2][O.sub.5]), potassium (100 kg/ha [K.sub.2]O) and 40% of nitrogen of each treatment broadcasted uniformly in the field at sowing time. While 40% of N at the beginning of stem elongation and 20% at the beginning of flowering stage was applied. In order to prevent the leakage of nitrogen from one plot to another, the distance of two meters was kept between two main plots and two replications from each other.

Wheat, Triticum aestivum L. Var. Chamran was seeded in rows spaced 20 cm a part at 400 seeds per square meter. Wild mustard, Sinapis arvensis L. and wild oat, Avena ludoviciana L. were sown between the two rows of wheat. To avoid the risk of non germination, three seeds instead of a single seed of wild oat and wild mustard each were sown. Excess seedlings of wild oat and wild mustard were removed by thinning process at the four leaf stage and the seedlings of desire density were maintained. Hand weeding method was followed to remove weeds except wild mustard and wild oat regularly during wheat growth. To determine the yield and yield parameters of wheat an area of two [m.sup.2] was harvested by sickle when the moisture content in wheat grains was 13-14%. The recorded data was analyzed statistically by using MSTATC computer software and a comparison of recorded data was done on the basis of Duncan's multiple range tests at Alfa level 5%.

Results And Discussion

Number of spikes per square meter:

The spike number of wheat decreased as weeds density increased in all nitrogen levels. The interspecific competition of wild mustard and wild oat increased by increasing nitrogen level. The results indicated that in the low level of nitrogen, the competitive ability of 25, 50 and 75 of wild oat [m.sup.-2] were higher than the densities of 5, 10 and 15 wild mustard [m.sup.-2] respectively. While the interference effects of wild mustard in the high level of N were strongly higher than wild oat (Table 1 and 2). The density of 15 plants of wild mustard decreased the spikes number of wheat by 12.3, 16 and 28.3% under 90, 150 and 210 kg N [ha.sup.-1] respectively (Table 1). While the density of 75 plants of wild oat decreased the spike number of wheat by 13.9, 15.1 and 18.4% as affected by 90, 150 and 210 kg N [ha.sup.-1] respectively (Table 2). With increasing the level of nitrogen the growth and biomass of weeds especially wild mustard goes on increasing which must be the reason for reduction in spike number of wheat. It seems that during luxuriant growth of weeds the allelopathic effects may be very high which caused negative effect on the wheat root system and thereby causing reduction in absorption of limited resources such as water and nutrients.

Giambalvo et al. (2010) stated that the interspecific competition of weed, Hordeum vulgare L. decreased the spike number of wheat, Triticum durum Desf Var. Simeto. by 8.9 and 27.3% under zero and 80 kg N [ha.sup.-1] respectively in 2005-06 whereas the spike number of Valbelice variety was decreased by 19.6 and 26.2% as affected by zero and 80 kg [ha.sup.-1] nitrogen respectively in 2005-6. Moosavi et al. (2004) concluded that increasing nitrogen level from 150 to 225 kg [ha.sup.-1] increased the spike number loss of wheat, Triticum aestivum L., in the presence of Sinapis arvensis. Interference effects of S. arvensis decreased the number of spikes by 18 and 30% under 150 and 225 kg N [ha.sup.-1] respectively as compared to weed free condition. They noted that although increasing nitrogen levels produced more tiller number but the number of unfertile tiller was increased by increasing nitrogen level.

The results indicated that the reduction of spike number in single competition of wild oat and wild mustard was less than mixed weed densities. The reduction of spike number was 23.1 and 20.6% in the presence of 15 plants [m.sup.-2] of wild mustard and 75 plants [m.sup.-2] of wild oat when they were grown separately. However in the mixed treatment of these two densities the reduction of spike number was 34.8 % (Table 3). Regarding additive series of this experiment, increasing weeds density increased the total number of plants in the certain area causing decrease in available space and increasing the inter as well as intraspecific competition for limited resources. Therefore, increasing competition decreased the spike number of wheat through decreasing the tiller number and increasing sterile tillers.

Number of grains per spike:

The results showed that the number of grains per spike was increased by increasing N levels while 1000 grain weight decreased. Wild mustard and wild oat interference reduced the grain number and 1000 grain weight of wheat at 90, 150 and 210 kg N [ha.sup.-1] (Table 1 and 2). The reduction in grain number per spike in the presence of weeds was due to the reduction in spikelet number per spike, number of florets and fertile florets. The results also showed that the number of wheat tillers increased by increasing nitrogen level (data not shown), but the grains produced by secondary tillers were very low in weight as compared to grains produced by primary tillers and hence the 1000 grain weight was reduced. Therefore, increasing nitrogen level decreased the 1000 grain weight through increasing tiller number. Hessami [9] observed a progressive reduction in grain number per spike and 1000 grain weight of wheat, Triticum aestivum L., with increasing Avena ludoviciana density, which decreased the grain number and 1000 grain weight by 16.9 and 11% respectively in competition with 160 A. ludoviciana plants [m.sup.-2].

Grain yield:

The inter-specific competition of wild mustard and wild oat decreased the grain yield of wheat in all nitrogen levels. Increasing nitrogen levels increased the competitive ability of wild mustard and wild oat and reduced the grain yield. The results indicated that the competitive ability of 5, 10 and 15 plants [m.sup.-2] of wild mustard at low level of nitrogen was less than 25, 50 and 75 plants of wild oat respectively. But increasing nitrogen level led to increase in competitive ability of wild mustard more than wild oat. The wheat grain yield decreased by 26.3 and 30.3% under 90 and 210 kg N [ha.sup.-1], respectively when wild oat density was 75 plants per [m.sup.-2] whereas the grain yield was decreased by 22.1 and 43.1% under 90 and 210 kg N [ha.sup.-1], respectively at 15 plants [m.sup.-2] of wild mustard density (Table 1 and 2).

The investigation of correlation between grain yield and yield components indicated that among the yield components, there is a high and positive correlation between grain yield and spike number of wheat and a reduction in this parameter is the most important factor in decreasing grain yield in the presence of wild mustard and wild oat (Table 4).

These results of present study were in line with Hassan and Khan [7], who reported that 50 wild oat [m.sup.-2], Avena fatua L., reduced the grain yield of wheat by 55.4, 58 and 59.6% under 75, 100 and 125 kg N [ha.sup.-1] respectively. Moosavi et al. [14] noted that there was a negative correlation between wild mustard, Sinapis arvensis L., density and wheat grain yield. Increasing N level from 150 to 225 kg/ha in the presence of S. arvensis, increased the loss in yield from 42.1 to 50.4%. This indicates that wild mustard could utilize the added nitrogen more efficiently and take a competitive advantage over wheat. Barker et al. [1] revealed that increasing crop loss due to weed competition in high fertility may be the result of higher plasticity in weeds in response to available resources. Ross and Van Acker [16] found that the competitive ability of wild oat in wheat field was significantly higher when nitrogen was applied.

The results of present study also indicated that the reduction of grain yield in single competition of wild mustard and wild oat was less than combined weed densities. For example, the grain yield decreased by 37.7 and 35.8% when 15 plants of wild mustard and 75 plants of wild oat were grown separately. However the reduction of grain yield was 52.7% in the combination of these two densities (Table 3). This result was in agreement with Mesbah et al. [13], who reported that root yield of sugarbeet reduced with increasing wild mustard and wild oat density, alone or in combination. The sugarbeet root yield decreased by 22 and 26% in alone competition of 3 wild oat and 0.8 wild mustard plants/m of row respectively. While the reduction of root yield in the presence of these two mixed densities was 38%.

Harvest Index (HI):

Harvest index shows how photosynthetic assimilations distribute between economic sink and other sinks of plant. The results indicated that HI decreased as wild mustard and wild oat density increased. It shows that the reduction in grain yield was higher than biomass reduction in the presence of wild mustard and wild oat. The density of 75 plants [m.sup.-2] of wild oat reduced the HI by 12.7, 11.9 and 14.2 % under 90, 150 and 210 kg N [ha.sup.-1] respectively, while the harvest index was decreased in presence of 15 plants [m.sup.-2] of wild mustard by 9.6, 11.7 and 19.8 % under 90,150 and 210 kg N [ha.sup.-1] respectively (Table 1 and 2). It shows that increasing nitrogen levels strongly increased the negative effect of wild mustard on HI and in high level of nitrogen the negative effect of wild mustard on grain yield was strongly higher than its effect on biomass.

These results were supported by the study of Rastgoo et al. [15], who concluded that in the presence of S. arvensis the harvest index of wheat was decreased by increasing nitrogen levels and among the nitrogen levels (100,150 and 225 kg [ha.sup.-1]) the maximum of HI loss was observed in the highest level of nitrogen. Zarea Feizabady et al [17] reported that the harvest index of wheat was decreased from 40.05 in weed free to 32.72 in the presence of 40 plants [m.sup.-2] of Avena ludoviciana.

Interaction between wild mustard and wild oat densities showed that the density of 15 plants of wild mustard and 75 plants of wild oat [m.sup.-2] decreased the HI of wheat by 17.1 and 17.6% when they were grown separately but in the combination of these two weed density the HI reduced by 27.6% as compared to control (Table 3).

Harvest index predicts the economic returns from cultivation of any crop. Its values increase or decrease along with positive or negative changes in several growth and yield attributes, as well as the physiological, biochemical and enzymological activities in the plant. The morpho-physiological characters are influenced by weed competition and their allelochemicals released into the environment through leaching, exudation and vaporization.

Conclusion:

The dominant weed species such as wild mustard and wild oat caused significant loss in grain yield and different yield components of wheat variety Chamran, even in increasing level of nitrogen. Hence, for improving yield and yield attributes in wheat effective management of weeds and fertilizer application is essential. Understanding of weed-crop interaction plays major role in yield improvement strategy. The results of present investigation clearly indicated that the nitrogen application for wheat was not useful in presence of weeds in general and specifically in the presence of wild mustard. Increasing nitrogen application especially in high weed densities had negative effects on wheat yield but had positive effect on growth of both the weeds. The results also showed that competition between wheat and single weed species either wild mustard or wild oat was much less than the competition between wheat and mixed weeds (wild mustard and wild oat) densities.

References

[1.] Barker, D.C., S.Z. Knezevic, A.R. Martin, D.T. Walters and J.L. Lindquist, 2006. Effect of nitrogen addition on the comparative productivity of corn and velvetleaf (Abutilon theophrasti). Weed Sci., 54: 354-363.

[2.] Bhadoria, P.B.S., 2011. Allelopathy: A natural way towards weed management. American J Experimental Agri, 1: 7-20.

[3.] Blackshaw, R.E., R.N. Brandt and H.H. Janzen, 2002. Weeds dine out on nitrogen and phosphorous. Better Crops., 86: 20-22.

[4.] Di Tomaso, J., 1995. Approaches for improving crop competitiveness through the manipulation of fertilization strategies. Weed Sci., 43: 491-497.

[5.] Giambalvo, D., P. Ruisi, G.D. Miceli, A.S. Frenda and G. Amato, 2010. Nitrogen use efficiency and nitrogen fertilizer recovery of durum wheat genotypes as affected by interspecific competition. Agron., J 102: 707-715.

[6.] Guillen-Portal, F.R., R.N. Stougaard, Q. Xue and K.M. Eskridge, 2006. Compensatory mechanisms associated with the effect of spring wheat seed size on wild oat competition. Crop Sci., 46: 935-945.

[7.] Hassan, G. and H. Khan, 2007. Effect of wild oats (Avena fatua L.) density on wheat yield and its components under varying nitrogen regimes. Pak J Bot., 39: 2585-2594.

[8.] Hesammi, E., 2011. Different densities of weeds and wild oats (Avena ludoviciana) and canary grass (phalaris minor) on yield and yield components of wheat cultivar Chamran. Advances in Environ Biol., 5: 2497-2500.

[9.] Hesammi, E. and S. Lorzadeh, 2011. Density and predominance of weeds in wheat fields of Khuzestan province. Aust J Basic & Applied Sci., 5: 1756-1759.

[10.] Iqbal, J. and D. Wright, 1997. Effects of nitrogen supply on competition between wheat and three annual weed species. Weed Res., 37: 391-400.

[11.] Labbafi, M.R., A. Hejazi, F. Mayghani, H. Khalaj and A. Mehafarin, 2010. Evaluation of allelopathic potential of Iranian wheat (Triticum aestivum L.) cultivars against weeds. Agric Biol J North America., 1: 355-361.

[12.] Mennan, H., 2003. Economic thresholds of Sinapis arvensis (wild mustard) in winter wheat fields. Pak J Agron., 2: 34-39.

[13.] Mesbah, A., S.D. Miller, K.J. Fornstorm and D.E. Legg, 1995. Wild mustard (Brassica kaber) and wild oat (Avena fatua) interference in sugarbeets (Beta vulgaris L.). Weed Technol., 9: 49-52.

[14.] Moosavi, K., M. Nassiri Mahalati, H. Rahimiyan, A. Ghanbari, M. Banayan and M.H. Rashe Mohasel, 2004. Seed rate and nitrogen Adv. Environ. Biol., 7(6): 1082-1087, 20'3 fertilizer effects on wild mustard (Sinapis arvensis L.) and winter wheat (Triticum aestivum L.) competition. J Iranian Field Crop Res., 1: 1-15.

[15.] Rastgoo, M., A. Ghanbari, M. Banaian and H. Rahimian, 2002. Investigation of amount and timing of nitrogen application effects on wild mustard (Sinapis arvensis) impact on yield and yield components of winter wheat. Pajouheshva-Sazandegi., 56(57): 16-24.

[16.] Ross, D.M. and R.C. Van Acker, 2005. Effect of nitrogen fertilizer and landscape position on wild oat (Avena fatua) interference in spring wheat. Weed Sci., 53: 869-876.

[17.] Zarea Feizabady, A., H. Sarban, M. Rajabzadeh and H. Khazaei, 2009. Competitive relationship between wheat cultivars at different densities of wild oat. Iranian J Field Crop Res., 7: 465-472.

(1) Pejman Behdarvand, (2) G.S. Chinchanikar, (2) K.N. Dhumal & (3) Mohammad Ali Baghestani

(1) Department of Agricultural and Natural Resources, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran.

(2) Department of Botany, University of Pune, India.

(3) Department of Weed Research, Plant Protection Research Institute, P.O. Box 19395-1454, Tehran, Iran.

Corresponding Author

Pejman Behdarvand, Department of Agricultural and Natural Resources, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran.

E-mail: pbehdarvand@yahoo.com
Table 1: Effect of wild mustard densities on yield and yield
parameters of wheat under different nitrogen levels

Nitrogen Wild mustard Spike No. Grain No. 1000 grain
levels density [m.sup.2] Per spike weight (g)
(kg/ha) (plants/
 [m.sup.2])

90 0 408.0 bc 26.2 de 39.0 a
 5 388.8 d 24.6 fg 38.3 ab
 10 372.0 ef 24.3 g 37.9 abc
 15 357.8 fg 22.7 h 37.6 bc

150 0 443.9 a 29.7 ab 37.3 bc
 5 419.3 b 28.5 bc 36.7 cd
 10 392.3 d 26.7 de 36.6 cd
 15 373.0 e 25.6 ef 35.5 de

210 0 448.8 a 30.3 a 37.2 bc
 5 395.0 cd 28.5 c 36.4 cd
 10 354.7 g 26.9 d 35.5 de
 15 321.9 h 25.9 de 34.3 e

Nitrogen Wild mustard Grain yield Harvest index
levels density (g [m.sup.2]) (%)
(kg/ha) (plants/
 [m.sup.2])

90 0 393.9 bc 34.4 abc
 5 360.6 de 33.8 bcd
 10 337.4 ef 32.9 cdef
 15 307.0 g 31.1 fg

150 0 444.5 a 35.9 a
 5 398.9 b 34.7 abc
 10 346.6 def 32.3 defg
 15 324.4 fg 31.7 efg

210 0 440.3 a 35.4 ab
 5 367.5 cd 33.2 cde
 10 298.9 g 30.6 g
 15 250.4 h 28.4 h

Means with different letters are significantly different
at P = 0.05, using Duncan's Multiple Range Test.

Table 2: Effect of wild oat densities on yield and yield
parameters of wheat under different nitrogen levels

Nitrogen Wild oat Spike No. Grain No. 1000 grain
levels density [m.sup.-2] Per spike weight (g)
(kg/ha) (plants/
 [m.sup.2])

90 0 415.1 b 25.9 d 40.2 a
 25 384.9 cd 24.3 e 38.5 b
 50 369.2 ef 23.9 e 37.4 bc
 75 357.5 f 23.8 e 36.7 cd

150 0 443.1 a 29.2 a 38.4 b
 25 416.3 b 28.5 ab 37.3 bc
 50 392.8 c 26.7 cd 35.8 de
 75 376.2 de 26.2 d 34.5 ef

210 0 418.8 b 29.3 a 37.7 bc
 25 395.8 c 28.7 ab 37.1 bcd
 50 364.0 ef 27.5 bc 34.8 ef
 75 341.7 g 26.1 d 33.9 f

Nitrogen Wild oat Grain yield Harvest
levels density (g [m.sup.-2]) index
(kg/ha) (plants/ (%)
 [m.sup.2])

90 0 408.7 b 35.3 a
 25 357.1 c 33.3 bcd
 50 331.7 cd 32.7 cde
 75 301.3 ef 30.8 fg

150 0 442.9 a 36.0 a
 25 395.9 b 34.6 ab
 50 352.4 c 32.4 def
 75 323.3 de 31.7 def

210 0 402.9 b 34.4 abc
 25 359.0 c 32.8 bcd
 50 314.4 de 30.9 efg
 75 280.8 f 29.5 g

Means with different letters are significantly different at
P=0.05, using Duncan's Multiple Range Test.

Table 3: Interaction effect of wild mustard and wild oat densities
on yield and yield parameters of wheat

Wild Wild oat Spike No. Grain No. 1000 grain
mustard density [m.sup.-2] per spike weight (g)
density (plants/
(plants/ [m.sup.2])
[m.sup.2])

0 0 490.4 a 30.7 a 40.2 a
 25 443.6 b 29.6 ab 38.4 bc
 50 410.7 c 27.9 cd 36.9 cdefg
 75 389.5 de 26.7 defg 35.7 efgh

5 0 433.3 b 29.0 bc 39.0 ab
 25 403.6 cd 27.6 cde 37.8 bcd
 50 390.7 de 26.2 fg 36.4 defgh
 75 376.6 efg 26.0 fgh 35.4 ghi

10 0 401.9 cd 27.1 def 38.5 bc
 25 382.4 ef 26.3 efg 37.4 bcdef
 50 359.7 gh 25.4 gh 35.7 fgh
 75 348.0 hi 25.2 gh 35.0 hi

15 0 377.1 efg 25.7 fgh 37.4 bcde
 25 366.3 fg 25.2 gh 36.8 cdefg
 50 340.3 i 24.5 hi 35.0 hi
 75 319.8 j 23.6 i 33.9 i

Wild Wild oat Grain yield Harvest
mustard density (g [m.sup.-2]) index
density (plants/ (%)
(plants/ [m.sup.2])
[m.sup.2])

0 0 530.2 a 38.7 a
 25 445.9 b 36.2 b
 50 388.6 c 34.0 c
 75 340.4 efg 31.9 cdef

5 0 441.1 b 36.3 b
 25 382.1 cd 33.9 c
 50 352.2 def 32.8 cde
 75 327.3 fgh 32.5 cdef

10 0 371.0 cde 33.8 c
 25 346.4 ef 33.0 cd
 50 304.4 hi 30.7 ef
 75 288.6 i 30.3 f

15 0 330.4 fgh 32.1 cdef
 25 308.3 ghi 31.2 def
 50 286.2 i 30.5 f
 75 250.9 j 28.0 g

Means with different letters are significantly different at
P=0.05, using Duncan's Multiple Range Test.

Table 4: Correlation coefficient among yield and yield parameters
of wheat

 Harvest Tiller 1000 grain Grain
 index number weight number

Tiller number 0.72 **
1000 grains weight 0.78 ** 0.34 *
Grains number 0.66 ** 0.95 ** 0.24 (ns)
Spikelet number 0.65 ** 0.96 ** 0.27 (ns) 0.97 **
Spike number 0.95 ** 0.84 ** 0.70 ** 0.76 **
Biomass 0.95 ** 0.84 ** 0.71 ** 0.76 **
Grain yield 0.98 ** 0.81 ** 0.74 ** 0.74 **

 Spikelet Spike Biomass
 number number

Tiller number
1000 grains weight
Grains number
Spikelet number
Spike number 0.76 **
Biomass 0.77 ** 0.99 **
Grain yield 0.74 ** 0.98 ** 0.99 **

*, ** significant at 5% and 1%, respectively, (ns) not significant
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Title Annotation:Original Article
Author:Behdarvand, Pejman; Chinchanikar, G.S.; Dhumal, K.N.; Baghestani, Mohammad Ali
Publication:Advances in Environmental Biology
Article Type:Report
Geographic Code:7IRAN
Date:Jun 1, 2013
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