INFLUENCE OF INTERCROPPING ONION WITH FABA BEAN ON FABA BEAN PRODUCTIVITY AND ITS QUALITY UNDER DIFFERENT RIDGE WIDTHS

INTERODUCTION

Faba bean (Vicia faba L.) is a legume crop grown primarily for its edible seeds (beans). Unfortunately, production of faba bean is still limited and falls to face the increasing local consumption of the crop. However, farmers suffer from high costs of production and consequently the reduction in the net income per unit area. This is due to the strong competition between faba bean and other strategic winter season crops such as wheat and clover on the limited arable land in Nile valley and Delta. In response to rising input costs and narrowing profit margins, scientific efforts are continually looking for ways to increase land use efficiency in Egypt. The cropping system adopted by the farmer in these soils must be physically viable, sustainable, less exhaustive acceptable to farming community and most important thing is that it should be economical. Moreover, mixing species in cropping systems may lead to a range of benefits that are expressed on various space and time scales, from a short-term increase in crop yield and quality, to longer-term agro-ecosystem sustainability, up to societal and ecological benefits (Malezieux et al., 2009).

Several different cropping patterns are followed in the Nile Valley and Delta areas, depending on the soil type and crops. Farmers are very responsive to technology transfer, extension activities and price incentives. Accordingly, it is important to address our efforts to this fundamental issue by intercropping. Intercropping is the growing two or more crop species simultaneously in the same field area and has been widely practiced worldwide (Francis, 1986). It provides an important pathway to fix atmospheric N₂, lower the risk of crop failure or disease and increase land use efficiency (Trenbath, 1993 and Morris and Garrity, 1993). Also, it is recommended to increase total agriculture products in Egypt (Metwally, 1999).

On the other hand, onion (Allium cepa L.) is produced for home consumption and as income sources for many small scale farmers and commercial growers in Egypt. Onions could be consumed fresh as in green salad or in many other forms (as bulbs for cooking and pickling consumption) and use in food processing. However, more information is needed for determining the optimal spatial arrangement of intercropping onion with faba bean through the manipulation of both hill distance and ridge width; it is a general principle that if appropriate number of plants is not used in the unit of land in fact the available potential has not been used optimally. Thereby, yield of faba bean can be governed by plant density and distribution of these plants per unit area with regard to onion cultivar and its plant density as the competition for environmental resources between the two field crops must be less than exists within the same species (Vandermeer, 1989). Yield per unit area declines since yield per plant tends to decrease with further increase in the plant density’ because of competition for growth factors between adjacent plants (Silvertooth, 2001). It is known that’ faba bean production is affected by different factors such as genotypes, plant distribution and plant density (Khalil et al., 2010 and Abd El-Rahman, 2014).

Hence, plant density is an important factor for the production of onion (Mlik, 1994). In this concern, Pakyurek et al. (1994) and Rizk (1997) showed that’ the highest planting density produced a noticeably higher yield of good quality bulbs than the lower sowing rate. Also, Dawar et al. (2007) revealed that’ maximum yield bulbs (7072 kg ha^-1) was produced at density of 80 plants/ 4m²’while minimum yield of bulbs (5133 kg ha^-1) was recorded at planting density of 40 plants/ 4m². Thus, the main target of this study is to identify the influence of different ridge widths and patterns of intercropping onion with faba bean on faba bean productivity and its quality.

 MATERIALS AND METHODS

The present investigation was carried out during the two successive seasons of 2013/14 and 2014/15 at the farm of Sers El-Lyan Agricultural Research Station, Agricultural Research Center, El – Menofiya Governorate, Egypt. The aim of the present investigation was to study the influence of different ridge widths and patterns of intercropping onion with faba bean on faba bean productivity and its quality. The treatments were the combinations between ridge widths and cropping systems as follows:

1. Growing two sides of ridge with faba bean plants (2 plants/hill spaced at 25 cm apart) on a ridge of 60 cm width. This pattern was expressed as sole faba bean (recommended).
2. Growing three rows of onion transplants spaced at 10 cm apart in the upper of ridge of 60 cm width. This pattern was expressed as sole onion (recommended).
3. Growing two sides of ridge with faba bean plants (2 plants/hill spaced at 25 cm apart) on a ridge of 60 cm width, besides growing one row of onion transplants spaced at 12 cm apart on the middle of the ridge. This pattern was expressed as 100% faba bean + 27% onion.       
4. Growing two sides of ridge with faba bean plants (2 plants/hill spaced at 25 cm apart) on a ridge of 60 cm width, besides growing one row of onion transplants spaced at 10 cm apart on the middle of the ridge. This pattern was expressed as 100% faba bean + 33% onion.       
5. Growing two sides of ridge with faba bean plants (2 plants/hill spaced at 25 cm apart) on a ridge of 60 cm width, besides growing one row of onion transplants spaced at 8 cm apart on the middle of the ridge. This pattern was expressed as 100% faba bean + 41% onion.       
6. Growing two sides of ridge with faba bean plants (2 plants/hill spaced at 25 cm apart) on a ridge of 60 cm width, besides growing one row of onion transplants spaced at 6 cm apart on the middle of the ridge. This pattern was expressed as 100% faba bean + 55% onion.
7. Growing three rows of faba bean plants on one ridge (2 plants/hill spaced at 25 cm apart) on a ridge of 90 cm width. This pattern was expressed as sole faba bean (I).
8. Growing four rows of onion plants on one ridge transplants spaced at 9 cm apart in ridge of 90 cm width. This pattern was expressed as sole onion (I).
9. Growing three rows of faba bean plants on one ridge (2 plants/hill spaced at 25 cm apart) on a ridge of 90 cm width, besides growing one row of onion transplants spaced at 8 cm apart in the same ridge. This pattern was expressed as 100% faba bean + 27% onion.       
10. Growing three rows of faba bean plants on one ridge (2 plants/hill spaced at 25 cm apart) on a ridge of 90 cm width, besides growing one row of onion transplants spaced at 6.6 cm apart in the same ridge. This pattern was expressed as 100% faba bean + 33% onion.       
    1. Growing three rows of faba bean plants on one ridge (2 plants/hill spaced at 25 cm apart) on a ridge of 90 cm width, besides growing two rows of onion transplants spaced at 10.6 cm apart in the same ridge. This pattern was expressed as 100% faba bean + 41% onion.       
    2. Growing three rows of faba bean plants on one ridge (2 plants/hill spaced at 25 cm apart) on a ridge of 90 cm width, besides growing two rows of onion transplants spaced at 8 cm apart in the same ridge. This pattern was expressed as 100% faba bean + 55% onion.       
    3. Growing four rows of faba bean plants on one ridge (2 plants/hill spaced at 25 cm apart) on a ridge of 120 cm width. This pattern was expressed as sole faba bean (II).
    4. Growing six rows of onion transplants spaced at 10 cm apart on ridge of 120 cm width. This pattern was expressed as sole onion (II).
    5. Growing four rows of faba bean plants on one ridge (2 plants/hill spaced at 25 cm apart) on a ridge of 120 cm width, besides growing two rows of onion transplants spaced at 12 cm apart in the same ridge. This pattern was expressed as 100% faba bean + 27% onion.
    6. Growing four rows of faba bean plants on one ridge (2 plants/hill spaced at 25 cm apart) on a ridge of 120 cm width, besides growing two rows of onion transplants spaced at 10 cm apart in the same ridge. This pattern was expressed as 100% faba bean + 33% onion.       
    7. Growing four rows of faba bean plants on one ridge (2 plants/hill spaced at 25 cm apart) on a ridge of 120 cm width, besides growing two rows of onion transplants spaced at 8 cm apart in the same ridge. This pattern was expressed as 100% faba bean + 41% onion.       
    8. Growing four rows of faba bean plants on one ridge (2 plants/hill spaced at 25 cm apart) on a ridge of 120 cm width, besides growing two rows of onion transplants spaced at 6 cm apart in the same ridge. This pattern was expressed as 100% faba bean + 55% onion.

Recommended cultural practices for growing faba bean and onion crops were used. The experimental soil texture was clay. Onion seedlings were sown on November 5^th and 7^th in 2013 and 2014 seasons, respectively, while, faba bean seeds were sown three weeks later. Onion seedlings (var. Giza 20) kindly provided by Onion Research Department, and faba bean seeds (var. Giza 843) kindly provided by Food Legumes Research Department, Field Crops Research Institute, ARC.

The experimental layout was conducted in split plot design with three replications by allocating the ridge widths in the main- plots and cropping systems in the sub-plots. Sub-plot area consisted of (12 ridges-60 cm width or 8 ridges-90 cm width and 6 ridges-120 cm apart) and 3 meters long.

The studied traits: At harvest, ten plants were taken randomly from each sub-plot to estimate the following traits:

1. Plant height (cm).
2. Number of branches / plant.
3. Number of pods / plant.
4. Number of seeds / plant.
5. Seed yield / plant (g).
6. 100 – seed weight (g).
7. Seed yield(ardab) / fad: it was recorded on the basis of experimental sub plot and expressed as ardab per fad.
8. Straw yield / plant (g).
9. Straw yield(ton) / fad: it was recorded on the basis of experimental sub plot and expressed as ton per fad.
10. Harvest index (%) according to Clipson et al. (1994) where

           Harvest index = Economic yield x 100

                                    Biological yield

1. Protein yield (kg/fad) = Seed protein content (%) x Seed yield (kg/fad)
2. Bulbs yield(ton) / fad: it was recorded on the basis of experimental sub- plot and expressed as ton per fad.
3. QUALITY OF FABA BEAN SEEDS:

1-      PROTEIN PERCENTAGE :

 The total N of faba bean seeds was determined using Microkjeldahl apparatus according to A.O.A.C. (2000). Crude protein content was calculated by multiplying total N by 6.25 for faba bean (Sadasivam and Manickam, 1997).

 2-       PHOSPHATE PERCENTAGE :

Phosphate percentage in seed was determined asreportedby Jachson  (1958).

 These analyses were done by the Regional Center for Food & Feed, Agricultural Research Center, Giza, Egypt.

 STATISTICAL ANALYSIS:

The data were subjected to proper statistical analysis of variance. The treatments means were compared by using the least significant differences (L.S.D.) test at 5% and 1% levels of probability, F test was also followed to differentiate among means of studied characters as recommended by Snedecor and Cochran (1973) and by SAS 2006 Statistical analysis program, SAS User´s Guide: Statistics. SAS Institute Inc Editor, cary, NC.

RESULTS AND DISCUSSION

A. YIELD AND ITS ATTRIBUTES

1. EFFECT OF RIDGE WIDTHS

Data in Table (1) showed that’ ridge widths had significant effects on plant height, number of seeds per pod, plant total weight, pods weight per plant, seed yield per plant, 100 – seed weight, seed yield per fad, straw yields per plant and per fad and harvest index, meanwhile numbers of branches and pods per plant and protein yield per fad were not significantly affected. These results indicated that’ the ridge width of 90 cm had the highest values of number of seeds per pod, seed yield per plant , 100 – seed weight and harvest index, in both seasons and plant height and plant and pods weights in the 2^nd season  without significant difference than the widest ridge of 120 cm. for no.of seeds/pod, plant height in both seasons, seed yield/plant, 100-seed weight and seed yield (ardab)/fad in the 2^nd season. Meanwhile’ the widest ridge of 120 cm produced the highest seed and straw yields per fad compared to the other ridge widths  (Table 1).

The increase in number of seeds per pod, pods weight per plant, seed yield per plant and 100 – seed weight at ridge width of 90 cm could be due to that the three rows of faba bean grown at 90 cm ridge width decreased intra-specific competition between plants of faba bean for basic growth resources as compared with the others. Accordingly, three rows of faba bean on ridge led to environmental balance between above and under – ground conditions for faba bean growth through enhancing the efficiency of photosynthetic process of the plant and consequently more dry matter accumulation in different parts of the plant organs. These results indicated that’ change ridge width played a major role in distribution of faba bean plants per unit area and thereby yield attributes of the plant during the early growth and development of faba bean. These results are in similar trends to those obtained by Ageeb (1983), Saleh (1985) and El-Douby et al. (2000).   

The significantly maximum seed yield per fad (11.32 ardab in 1^st season and 10.35 ardab in 2^nd season) and straw yield per fad (3.80 ton 1^st season and 3.78 ton in 2^nd season) were obtained at 120 cm ridge width. These results could be attributed to that the widest ridge width had the highest number of plants per unit area’ which reflected positively on final yield per unit area and harvest index. Similar trend of results were observed by Loss et al. (1998) who demonstrated that’ increases in plant numbers at higher densities more than compensated for a lower seed weight per plant, effectively producing higher yields per hectare. 

2. Effect of cropping systems

Data in Table (1) showed that’ cropping systems had significant effects on plant height, numbers of branches and pods per plant, number of seeds per pod, plant total weight, pods weight per plant, seed yield per plant, 100 – seed weight, seed and protein yields per fad, straw yields per plant and per fad and harvest index in both seasons, except straw yield per plant in the second season wher the values did n’t reach to the level of significant. The results showed that’ sole faba bean had the highest numbers of branches per plant pods per plant, seeds per pod, plant total weight , pods weight per plant, seed yield per plant, 100 – seed weight, seed yield per fad, protein yield per fad  and harvest index in both seasons compared to those of intercropping patterns. However, the sole faba bean treatment had no significant difference than 100% faba bean + 27% onion cropping system for no.of branches/plant,no.of seeds/pod and protein yield/fad.

Sole culture of faba bean could be decreased intra–specific competition between plants of the same species for basic growth resources, especially solar radiation which increased numbers of branches and pods per plant and resulted in a positive effect on 100 – seed weight and harvest index compared to those by intercropping patterns. Conversely, sole faba bean produced the lowest straw yield per plant (47.33 g in 1^st season) and straw yield per fad (2.71 ton in 1^st season and 3.33 ton in 2^nd season) compared to those of intercropping patterns. Accordingly, it is expected that growth resources such as water and nutrients were more completely absorbed by sole faba bean and converted to crop biomass during the early growth and development stages of faba bean plants compared to those of intercropping patterns.

With respect to intercropping  patterns, the results in Table (1) revealed that’ intercropping pattern of 100% faba bean + 27% onion came in the first rank, where it produced the highest numbers of branches per plant  and pods per plant, number of seeds per pod, pods weight per plant, seed yield per plant, 100 – seed weight, seed yield per fad  and protein yield per fad in both seasons, compared to those of the other intercropping patterns. Conversely, intercropping pattern of 100% faba bean + 55% onion produced the lowest number of seeds per pod, pods weight per plant, seed yield per plant, 100 – seed weight, seed yield per fad and protein yield per fad  in both seasons, compared to those of the other intercropping patterns.On the other hand, the same intercropping patterns gave the highest values of straw yield per plant and per faddan in both seasons.

These results could be due to that intercropping pattern of 100% faba bean + 27% onion furnished better environmental resources for faba bean plants to grow well during the early growth and development stages compared to the others. In other words, the lowest plant density of onion could be decreased inter – specific competition between plants of the intercrops for basic growth resources’ which reflected positively on the economic yield of intercropped faba bean.

Table (1): Effect of ridge width, cropping systems and their interaction on faba bean yield and its attributes during

                2013/14 and 2014/15 seasons.

Table (1): Continued.

        Table (1): Continued.