ABTRACT

In southeastern US, double cropping of winter wheat with summer crops has proved to be very profitable and beneficial for soil management and winter canola (Brassica napus L.) also has similar potential. Therefore, performance of winter canola in rotation and as a double crop with corn, sorghum, soybean and cotton were evaluated for two years. Rotational effects on canola plant height, number of pods per plant, number of seeds per pod, and seed weight were not significantly different in comparison to fallow in 2003 but they were significant in 2004. The rotational effect on final plant population was significant in 2003. In 2003, rotating canola after soybean significantly increased canola seed yield (2739 kg ha-1) than after fallow (2557 kg ha-1). In 2004, canola planted after soybean gave the highest yield (3129 kg ha-1), which was non significantly different than after corn (2938 kg ha-1) but was significantly higher than after sorghum (2650 kg ha-1) or cotton (2521 kg ha-1). The fatty acid profile, saturated fat and protein contents in canola oil were not affected by rotation.

INTRODUCTION

The term “canola” is a registered trademark of the Canadian Canola Association and refers to new cultivars of oilseed rape that have less than two percent erucic acid and no more than 30 micromoles per gram glucosinolates. The seeds contain 40 percent oil by weight and this oil contains 6 % saturated fats, which is the lowest among all vegetable oils. The canola meal contains about 37% protein and is used as a high protein livestock poultry feed (Murdock et al., 1992). In row-crop production system in southern US, except wheat, rye and barley, no other winter crop has been tried in rotation with the summer crops; however, winter type Brassica napus L. is the oilseed crop for southeastern US (Raymer et al., 1990) which has a potential. Crop rotation is an integral part of the crop production system and it improves crop diversity and yields (Dabney et al., 1988). A major benefit of crop diversity is that it increases grain yields (Anderson et al., 2005) and helps in disease management (Angus and Herwaarden, 2001). In Southeastern US, currently wheat is the major winter annual crop grown in rotation with summer crops. Like winter wheat, double cropping of winter canola with summer crops has the potential for all rotational benefits (Buntin et al., 2002; Raymer et al., 1990). Because of similarities of life cycles and management requirements to wheat, canola can fit as a companion or an alternative crop to wheat. However, research data on the effects of summer crops’ rotation on canola is lacking. Therefore, the current study on canola planted in rotation with soybean, corn, sorghum, and cotton was undertaken with the following objectives:

OBJECTIVES

To determine the rotational effects of soybean, corn, sorghum, cotton as summer crops on growth and yield of winter canola.

MATERIALS AND METHODS

The experiment was conducted during 2002-2003 and 2003-2004 crop growing season in Hazel Green, Alabama. The experiment consisted of six treatments (four summer crops, wheat and canola) planted in a randomized complete block design with four replications. Summer crops: soybean, corn, sorghum and cotton were planted on May 11, 2002. Canola was planted after the harvest of these crops (Fig. 1) on September 28, 2002, to compare with canola and planted after fallow. During 2003, summer crops were planted on May 10, 2003 and canola and wheat were planted on Oct 2, 2003 which were harvested in June 2004 (Fig. 2).The details of the treatments are as follows:

Treatment Crop rotation Notation 1. Soybean---Canola----Soybean -----Canola Sy-C 2. Corn--------Canola----Corn-----------Canola M-C 3. Sorghum--Canola----Sorghum------Canola S-C 4. Cotton-----Canola ----Cotton --------Canola G-C 5. Fallow-----Canola-----Fallow---------Canola F-C

Canola was planted on a tilled seedbed with a drill planter @ a seeding rate of 6.18 kg ha-1. Soybean (67 kg ha-1), corn (9 kg ha-1), sorghum (9 kg ha-1), and cotton (9 kg ha-1) and wheat (67 kg ha-1) were no–till planted at their recommended seeding rates. Data on rotational effects of summer crops on canola was collected for the following plant parameters: Plant height, final plant population, number of pods per plant, number of seeds per pod, seed weight, and seed yield.

Summer crops yieldThe final yield of soybean, corn, sorghum, and cotton has been expressed as kg ha-1. Data collected were analyzed for analysis of variance using SAS programming and means were separated by Tukey’s test.

Winter Canola Performance in Rotation with Summer CropsSuresh Kumar, Udai R. Bishnoi, and E. Cebert

Department of Plant and Soil Science, Alabama A&M University, Normal, Alabama 35762

RESULTS AND DISCUSSION

Plant heightDuring both 2003 and 2004 growing seasons, plant height of canola planted after fallow were numerically higher than when planted after rotation with soybean, corn, sorghum, and cotton (Table 1); however, the differences were non significant during 2003. During 2004, canola plant height was significantly influenced when planted after fallow, corn, cotton, and sorghum than when planted after soybean.

Final plant populationThe highest plant population due to rotation was observed in canola planted after soybean, thus giving significantly highest yield over other summer crops, except corn (Table 1). Angadi et al., (2003) observed that the decreases in population to 10 and 5 plants m-2 reduced seed yield by 42 to 92% of 80 plant m-2.

Pods per plant The response of canola for pods per plant was not significant when planted after soybean, corn, sorghum, cotton and fallow during 2003. In 2004, a significant increase in number of pods (223.4) was obtained in canola planted after soybean in comparison to canola planted after corn (193.7) and cotton (192.3) in 2004 (Table 2).

Seeds per pod and Seed weightDuring both the growing seasons (2003 and 2004), canola planted after soybean gave numerically the highest number of seeds per pod and seed weight than canola planted after corn, sorghum, cotton, and fallow; however, the differences were significant only in 2004 (Table 2 and 3). Canola planted after soybean produced significantly higher seed weight than canola planted after sorghum and cotton in 2004, but not in 2003. Early-formed pods at the top of the main raceme have the developmental advantage (Mendham and Salisbury, 1995) that might have masked the smaller variations in seeds per pod or seed weight in the present study.

Seed YieldThe rotational effects in canola seed yield during 2003 was significantly higher when planted after soybean ( 2739 kg ha-1) than canola planted after cotton ( 2445 kg ha-1) and sorghum ( 2440 kg ha-1), however, the difference was not significant to canola yield planted after soybean, corn, and fallow (Table 3). During 2004, canola planted after soybean gave the highest seed yield of 3129 kg ha-1, followed by corn (2938 kg ha-1), fallow (2876 kg ha-1), sorghum (2650 kg ha-1), and cotton (2521 kg ha-1) and was significantly different from canola planted after sorghum and cotton. Such rotational effects have been observed by Harris et al. (2002) and they reported that wheat grown after canola yielded 11% more grain than wheat grown after wheat.

CONCLUSIONS

1. Canola height was more when planted after fallow, corn, cotton, and sorghum than when planted after soybean in 2004 only. 2. Canola planted after soybean produced higher pods per plant than canola planted after corn and cotton in 2004 but not in 2003. 3. Canola produced higher yield when planted after soybean, corn and fallow than after sorghum and cotton during both growing seasons.

REFERENCES

Anderson, R. L. 2005. Are Some Crops Synergistic to Following Crops? Agron. J. 97:7-10.

Angadi S. V., H. W. Cutforth, B. G. McConkey and Y. Gan. 2003. Yield Adjustment by Canola Grown at Different Plant Populations under Semiarid Conditions. Crop Science 43:1358-1366.

Angus, J. F., and A. F. van Herwaarden. 2001. Increasing water use and water use efficiency in dryland wheat. Agron. J. 93:290–298.

Buntin G. David, Paul L. Raymer, Craig, W. Bednarz, Dan V. Philips, and Richard E. Baird.2002. Winter crop tillage and Planting Date Effects on Double crop cotton. Agron J. 94:273-280.

Dabney, S. M., E. C. McGawley, D.J.Boethel, and D.A.Berger.1988. Short-term rotation systems for soybean production. Agron.J.80: 197-204.

Harris, R. H., G. J. Scammell, W. J. Müller and J. F. Angus. 2002. Australian Journal of Agricultural Research 53(11) 1271 – 1283.Mendham, N. J., and P. A. Salisbury. 1995. Physiology: Crop development, growth and yield. p. 11–64. In D. Kimber and D.I. McGregor (ed.) Brassica oilseeds: Production and utilization. CAB International, UK.Murdock Lloyd, Jim Herbek and Steven K. Riggins.1992. ID 114 Canola production & management.

Raymer, P. L., D. L. Auld, and K. A. Mahler. 1990. Agronomy of canola in the United States. p. 25–35. In: F. Shahidi (ed.), Canola and rapeseed: Production, chemistry, nutrition, and processing technology. Van Nostrand Rhienhold, New York.

Table 1. Analysis of variance and treatment means for plant height and final plant population of canola after rotation with summer crops.

Plant height (cm) Final plant population

2003 2004 2003 2004

Mean Mean Mean Mean

Source   df square   df square   df square   df square

Rep 3 11.5 3 0.02 3 9.12 3 15.52

Treatment† 4 17.18 4 15.21** 4 53.05** 4 49.00*

Error 12 6.85 12 2.17 12 4.78 12 7.43

Treatment

% variation % variation % variation % variation

from FC Mean from FC Mean from FC Mean from FC Mean

Sy-C -4.4 106.1ns -4.49 102.0b 21.6 40.8a 21.5 39.5a

M-C -2.9 107.8ns -1.69 105.0ab 16.4 39.0ab 15.4 37.5ab

S-C -4.1 106.4ns -3.79 102.8ab 0 33.5b -1.5 32.0b

G-C -4.4 106.2ns -3.63 102.9ab -1.5 33.0b -0.8 32.3b

F-C - 111.0ns - 106.8a - 33.5b - 32.5b

Grand mean   107.5     103.9     36.0     34.8

*,** Significant at the 0.05 and 0.01 probability levels, respectively.

†Sy-C, soybean-canola; M-C, corn-canola; S-C, sorghum-canola; G-C, cotton-canola; F-C, fallow-canola.

Fig. 1. Summer crops grown in rotation with canola. Fig. 2. Canola and wheat grown in rotation after summer crops.

Table 2. Analysis of variance and treatment means for number of pods per plant and seeds per pod of canola after rotation with summer crops.

Pods per plant Seeds per pod

2003 2004 2003 2004

Source dfMean

square   dfMean

square dfMean

square   dfMean

square

Rep 3 176.13 3 64.55 3 3.01 3 4.56

Treatment† 4 316.83 4 666.70** 4 2.33 4 0.45**

Error 12 127.93 12 74.69 12 1.26 12 0.37

Treatment

% variation % variation % variation % variation

from FC Mean from FC Mean from FC Mean from FC Mean

Sy-C -9.49 195.5ns 5.9 223.4a 5.9 18.1ns 5.5 18.1a

M-C -4.86 205.5ns -8.2 193.7b 3.3 17.6ns -0.4 17.1ab

S-C -6.37 202.2ns -0.7 209.6ab -5.3 16.1ns -5.6 16.1bc

G-C -10.3 193.8ns -8.9 192.3b -2.5 16.6ns -10.9 15.2c

F-C - 216.0ns - 211.0ab - 17.1ns - 17.1ab

Grand mean 202.6     206.00     17.1     16.7

*, ** Significant at the 0.05 and 0.01 probability levels, respectively; ns, non-significant.†Sy-C, soybean-canola; M-C, corn-canola; S-C, sorghum-canola; G-C, cotton-canola; F-C, fallow-canola.

Table 3. Analysis of variance and treatment means for seed weight (g/1000 seeds) and yield of canola after rotation with summer crops.

Seed weight Yield

2003 2004 2003 2004

Source dfMean

square   dfMean

square   dfMean

square   dfMean

square

Rep 3 0.12 3 0.01 3 10562.6 3 13363.5

Treatment† 4 0.14 4 0.14** 4 59547.3** 4 230838**

Error 12 0.04 12 0.01 12 6191.8 12 18833.3

Treatment

% variation Mean % variation % variation % variation

from FC Mean from FC Mean from FC Mean from FC Mean

Sy-C 2.1 4.8ns 0.8 4.6a 7.1 2739a 8.8 3129a

M-C -1.3 4.6ns -0.6 4.5a 0.5 2570ab 2.1 2938ab

S-C -6.7 4.4ns -8.3 4.2b -4.6 2440b -7.9 2650bc

G-C -6.4 4.4ns -6.1 4.3b -4.4 2445b -12.4 2521c

F-C - 4.7ns - 4.5a - 2557ab - 2876abc

Grand mean 4.6     4.4     2550.0     2823.0

*, ** Significant at the 0.05 and 0.01 probability levels, respectively; ns, non-significant.†Sy-C, soybean-canola; M-C, corn-canola; S-C, sorghum-canola; G-C, cotton-canola; F-C, fallow-canola.

CANOLA

WHEAT

CANOLA

SORGHUM

COTTON

SOYBEAN

CORN

SORGHUM

COTTON

SOYBEAN

CORN