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The Effect Of Live Mulches On Tomato Yield Under Weed Competition
Somaye Rafie
aHamid Reza Mohammaddoust Chamanabad
b, , Ali Asghari
ca : Yasuj Univrrsity, Faculty Of Agriculture Science, Agriculture and Physiology Department, University of Mohaghegh Ardabili, Faculty of Agriculture, Faculty of Agronomy and Plant Breeding, Universitty Street, postal
code 7591874934, Iran.
*Corresponding author's e-mail:[email protected].
ABSTRACT
over crops are an important component of crop production management in sustainable agriculture. The purpose of this study was to evaluate the tomato yield when grown under different live mulches and their planting date.
Therefore, in 2013, effect of planting date (One month before tomatoes transplanting, at the same time as transplanting and one month after tomatoes transplanting) of three types live mulch (winter rye, red clover, winter canola and a control without live mulch) on tomato yield were evaluated at the Zarghan city 65 km from Shiraz, Iran, in a split plot experiment laid out in a randomized complete block design with three replications. The results showed that live mulches increased tomato yield in weedy and weed free plots 60.42 and 35.0% respectively.
Among the live mulches, number of fruits plants-1 and the highest tomato yield obtained where red clover grown as live mulch and this yield was significantly greater than the yield produced from control and winter rye treated plots.
The winter rye live mulch treatment was a poor treatment as it had negative effect on tomato yield. The results suggest that red clover live mulch will provide a good combination with tomato, and can plays an important role in improving soil fertility, weed control, and ultimately increase tomato yield.
Keywords: :Non-chemical weed management, Soil fertility, Sustainable production, Vegetable crops
INTRODUCTION
Although agrochemicals initially had a role in increasing crop yield, but their Application have been problems such as environmental pollution and human health risks. On the other hand, there is observed a growing concern for its protection and keeping in good conditions for the future generations. In Regarding this issue, there have been introduced into the practice the cultivation systems in which the great attention is being paid to limiting use of chemicals for plant protection as well as herbicides. Recently, with the development of sustainable production systems, researchers are looking for ways to not only maintain or increase crop production, but also reduced use of the chemicals. Cover crops including live mulches are an important component of sustainable agricultural systems and can play an important role in increasing the yield crops and are one of the most important replacement methods used instead of agrochemicals (Brust et al, 2013, Campiglia et al, 2010; Ngouagio et al, 2003). Researchers showed that tomato yield in plots with mulch were more than in plots without mulch (Akintoye et al 2005, Hudu et al, 2002, Hutchinson and McGiffen, 2000). Akintoye et al (2005) found that cucumber live mulch produced the highest number of tomato fruits plant-1 and yield. Increased crop yield, resulting live mulches are due to their impact on weed control, disease control, soil, improved soil fertility through nitrogen fixation, improve soil structure, preventing the leaching of nitrogen, increasing soil organic matter and soil erosion (Gibson et al 2011, Blanko- Canqui et al, 2012;, Doane et al, 2009; Sainjo et al, 2002). Positive effect of live mulches on reduction of weed population could be as a result of their high competition, regarding water, nutrient and light, as well as live space, hence can increase crop yield (Abdul-Baki et al, 1996; Samarageewa et al, 2006). An important property, which ensures them the advantageous development, is their rapid growth and good covering of soil surface, as early as since the beginning of growing period. Samarajeewa et al (2006) reported that finger millet as a cover crop can inhibit markedly weed growth in due to the high tillering ability. Also, live mulch planted between rows might limit weed seed production (Gibson et al, 2011).
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Another advantage of cover crops is nitrogen fixation by legumes or reduction nitrogen leaching, which can provide a large part or even all of the nitrogen needs of the agroecosystems (Doane et al, 2009; Griffin et al, 2000;
Reinbott et al, 2004; Thiessen et al, 2001). Griffin et al (2000) reported that although the biomass of three cover crop (alfalfa, winter rye and vetch) were the same, but the amount of nitrogen added to the soil in legume plants was more than rye. So that, maize yield response to increasing nitrogen up to 156 kg per hectare, increased linearly, where rye cover crop was planted, while where legumes were grown corn yield did not show any response to nitrogen. Doane et al (2009) found that the use of legumes as cover crop increased corn yield. Reinbott et al (2004) suggested that highest corn yield obtained when grown with legume crops.
Managing competition between live mulches and the target crop is a major concern for the farmers. There have been undertaken numerous attempts to minimize this competition. The trials on this subject involve providing vegetables with optimal growing conditions by proper supply of nutrients and water, the choice of sowing time for live mulches as well as direct operations for reduction of their growth rate. The term of live mulches sowing should be chosen carefully so they can ensure optimal soil covering, but at the same time they should not be high competitive to target crop. Gibson et al (2005) reported that buckwheat used as live mulch in tomato did not negatively affect the fruit yield, if sown after critical period of weed competition. Brainard et al. (2004) found that at the earliest sowing term of live mulch from rye or oat, when the mulch produced the highest amount of biomass, there was observed even twelve fold reductions in weeds biomass in cabbage cultivation. Hall et al (1984) found that planting of cover crop at the same time with corn decreased corn yield from 39 to 50%, but when cover crop removed by herbicide yield loss occurred only 5 to 9%.
These researches show that live mulches are best suited in the species with relatively long vegetation period, grown from transplants. The most important attributes required for species used as live mulches are quick emergence and soil covering, short height, low water and nutrients demands. In most cases, the legume crops or cereals, especially winter rye is used for this purpose. The purpose of this study was evaluation of effect of live mulches type and planting date on tomato yield under weed competition.
MATERIALS & METHODS
Experiments were carried out in a field located in Zarghan, 65 km from Shiraz, Iran (31.27oS, 55.50oE) in 2013. The soil was silt clay with pH of 8.3, 1.4% organic matter, 0.06% N, 15ppm P2O5 and 31ppm K2O.growing conditions were total annual rainfall of 337.8 mm and mean temperature 18oc. Laboratory works was done in research laboratories at Agricultural Sciences faculty, University of Mohaghegh Ardabili.
Factors included live mulch type (winter rye Secale cereal L., red clover Trifolium pretense L., canola Brassica raps and without live mulch as control) and three planting date of live mulch (one month before tomato transplanting, at the time of transplanting and one month after transplanting). The experimental design was a split-plot with three replications. Live mulch type and their planting date as main plots and presence/absence of the natural weed flora as subplots. Mouldboard plowing was done to a depth 30 cm in October last year. Secondary disk and furrowing was ready at May 2014. Cover crops (wheat, canola and Red clover in each treatment) were planted in the furrow.
To provide seedlings, tomato seeds, Apollo cultivar, were planted in the greenhouse at the on 20 April 2014.
Transplanting was done on 20 May after seedling establishment. Plots were 3 m (comprising five rows with a distance of 60 cm and 30 cm between plants) wide and 6 m long. Each plot was divided into two parts: one part was controlling weeds during the growing season. In the other half weeds grown during the growing season. Irrigation was done in times of need. To meet the nitrogen requirement, 250 kg ha-1 urea was used in the seven-leaf stage and flowering stage. Tomato yield were collected of the two middle rows for two harvest interval 15 days from main and beside brancheses seperatly.
Statistical analysis was performed using MSTATC. Duncan's multiple range tests at the 5% level was used to compare treatment means.
3 RESULTS AND DISCUSSION
Analysis showed that under weedy and weed free, fruit number of main branches in first harvest was significantly different between type live mulch (Table 1). In weed competition decreased fruit number of main branches 23.2%. Results showed that under weedy live mulches had more positive effect than weed free condition.
In conditio weedy and weed free, planting of canola live mulch increased fruit number of main branches in first harvest by 15 and 67% compared with control (without live mulch) respectively. Under weedy, Compared to winter rye, canola increased fruit number of main branches in first harvest by 100% (Fig. 1).
Fig. 1. The effect of planting date of live mulches under weed free (A) and live mulches type under weedy and weed free on number fruit in main branches
Planting date of live mulches had a significant effect on fruit number of main branches in first harvest only under weed free. Compared to late planting date, the early planting (30 days before tomato) increased fruit number of main branches in first harvest 18 to 24% (Fig 2). In second harvest, both type and planting date of live mulches had not significantly effect on fruit number of main branches.
Such as main branches, fruit number of beside branches was decreased three fold by weed competition. This effect was higher where live mulches were not grown. In first harvest, fruit number of beside branches was increased only in weedy plots by live mulches, but in second harvest, this trite were increased both weedy and weed free plots by 1.76 and 1.5 time by live mulches respectively. In first harvest, red clover and canola live mulch increased fruit number of beside branches to 2.8 times in weedy plots (Fig 4), but in second harvest this effect had diminished in weedy plots. Under weed free, live mulches increased this trite from 1.45% for winter rye to 1.74%
for red clover.
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Fig.2. The effect of live mulches on number fruit in tomato beside branches in first and second harvest under weedy and weed free.
Fig.3. The effect of live mulches type on number fruit in tomato beside branches in first harvest under weedy (A) and under weedy and weed free on second harvest.
ANOVA showed that live mulches had a significant effect on tomato yield both in first harvest and second harvest. Also, their type and planting date of live mulches affected significantly total tomato yield (Table 1). Tomato yield was decreased 7-15 t ha-1 by weed competition. The results showed that cover crops increased tomato yield in weedy and weed free plots 60.42 and 35.0% respectively (Fig. 4). The live mulch effect on yield was higher in first harvest. So increased tomato yield in first harvest was 83.8 and 35% and in second harvest 56.5 and 35% in weedy and weed free plots respectively. In weed free plots, the highest tomato yield obtained where red clover grown as live mulch (Fig. 5). In this condition, tomato yield was more 1.5 time than control (without live mulch and weed). In plots which grown weed, live mulches increased tomato yield more than weed free treatments (Fig. 6). In weedy condition, in plots with live mulches, tomato yield was two times higher than control. Red clover and canola has affected tomato yield more than winter rye.
c
b
a a
d d
d d
0 1 2 3 4 5 6 7
Control Winter rye Canola Red clover
N o. f ru it in bi si de br an ch es
B
Weed free Weedy
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Table 1. ANOVA of the studied factors on the tomato yield
Treatment df
Mean square
First harvest Second harvest Total yield
Weed free weedy Weed
free weedy Weed
free weedy replication 2 17471.73ns 16361.34ns 1.192ns 3.31ns 0.861ns 1.75ns Controls vs others 1 234731.56** 174152.56** 79.37** 909.19** 3.675** 4.41**
Type 2 472280.26** 1506231.81** 154.52** 465.75** 3.028** 14.11**
Planting date 2 7170.81ns 203239.09** 0.70ns 95.04** 0.083ns 0.528**
Interaction 4 1684.06ns 200388.96** 0.94ns 320.69** 0.444ns 0.097**
Error 18 3068.03 6020.60 1.10 35.50 0.225 0.269
C V )%( 5.13 11.06 3.26 8.24 8.06 18.01
Fig 4. The effect of live mulches on tomato yield under weedy and weed free.
Fig 5. Effect of live mulch type on total tomato yield in weed- free plots
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Fig 6. The effect of type and planting date of live mulches on tomato yield under weedy.
The results showed that planting live mulches, especially in the presence of weeds had a positive impact on number fruit and tomato yield. Under weed free, red clover as a live mulch increased tomato yield by 57.07%
compared with control. The increase yield was 15% and 67% more than winter rye and canola respectively. Also, under weedy, the effect of red clover and canola was more than winter rye. In this plots, the tomato yield was same weed free. Live mulches in vegetable crops should have the ability to suppress weeds without stressing the crop as a result of quick emergence, fast soil coverage and short height and to favor nitrogen availability (Blanco-Canqui et al, 2012;, Lawley et al, 2011). However, many experiments have shown that the greatest impact was on weed control.
Brust et al (2013) reported that live mulches reduced weed density to 77-81% and their dry weight to 96%.
Among live mulches, red clover has the greatest impact maybe due to nitrogen biological fixation and improving tomato competitiveness with weeds or low growth and excellent soil surface coverage. Many researchers reported that legumes as live mulches reduce need to nitrogen fertilizers (Blanco-Canqui et al, 2012; Doane et al, 2009). Doane et al (2009) reported that the amount of nitrogen in the soil after three years vetch cover crop were three times more than control.
CONCLUSIONS
Researchers suggested that spring planted small grains, such as winter rye can be used as live mulch although sometimes crop yield reduction may be a problem. But the use of these plants, given the advantages mentioned in the present text and the results obtained from this study, can lead to a reduction in the use of pesticides and common
agricultural inputs to sustainable agriculture.
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