Abstract: To study the performance of maize in intercropping system with soybean under different planting patterns and nitrogen levels an experiment was carried out at student`s experimental farm, Sindh Agriculture University Tandojam during kharif season 1990. The results indicated that plant height, number of leaves per plant, 1000 grain weight of maize increased with an increase in nitrogen levels. Maximum grain yield of 1692 kg ha–1 was recorded from highest dose (120 kg N ha–1). Intercropping of soybean in maize rows did not show any adverse effect on maize plant height, number of leaves, 1000 grain weight as well as grain yield of maize. However, maize under mono- culture recorded greater grain yield ha–1. The results further revealed that Soybean planted alone gave better performance in respect of seed yield ha–1 and yield contributing parameters. While seed yield and other yield contributing parameters of soybean were significantly affected in intercrop treatments due to competition with main crop.
INTRODUCTION
Maize (Zea mays L.) is a valuable food grain and high substitute of corn oil in the world. It has versatile usages in human food over tropical sub-tropical regions[1].
Intercropping is a wise pre time management for increasing potentiality of soil and production per unit area as well as income. Intercropping system is more productive than the sole crop[2], especially under adverse conditions[3]. Intercropping advantages are substantial and are achieved by the simple experiment of growing crops together[4]. Legumes which fix atmospheric nitrogen besides meeting their own N requirements, serves as a viable via media for soil enrichment. This eventually helps in meeting the N needs of cereals partially[5]. Singh and Chand[6] reported that maize gave grain yield of 2.15 t ha-1 when intercropped with soybean, which gave an additional yield of 0.58 t ha-1. Net profit of 120 kg N ha-1 was higher in maize/soybean mixture than in maize alone. In general beneficial effect of legumes intercropped with cereals like maize has been observed under low fertility conditions[7,8]. Willey et al.[9] concluded that legume/non legume intercropping systems gave higher yields than mon-culture due to efficient utilization of resources over time. Khan[10] reported that different maize- summer legumes intercropping systems did not affect plant population per unit area of maize crop significantly. Singh et al.[11], Pandey et al.[12] and Kalra and Ganger[13] reported an increase in maize yield and net profit when grown in association with soybean. In plains of Punjab, soybean or black gram increased maize yield by 2000-4000 Kg ha-1 when grown in association[14]. The multiplicity of possible plant combinations and the interaction in the crop mixtures have complicated the effective intercropping system. However, for a given set of combinations with in a specific system, a method of arranging two crops for maximum yield benefits could be formulated. Thus the present study was designed to develop such a method, using maize/soybean combinations under different planting patterns and N levels and to observe changes in yield and yield components of intercrops.
MATERIALS AND METHOD
To evaluate the performance of maize intercropped with soybean under different cropping patterns and nitrogen levels an experiment was carried out at student’s farm, Sindh Agriculture University, Tandojam during kharif season 1990. The experiment was laid out under Randomized Complete Block Design with eight treatments and four replications. The ultimate plot size was 4x3.6 m. Nitrogen levels were 0, 60, 90 and 120 kg N ha-1 and the intercropped treatments were maize alone, paired rows of maize at 40 cm + soybean, triple rows of maize at 90 cm + soybean. Seed bed was prepared by giving two dry ploughings with disc and gobble plough each followed by clod crushing. The land was leveled to facilitate uniform irrigation etc. The sowing was done by the mean of single coulter hand drill on February, 1990. Uniform application of recommended fertilizer dose was made. All the cultural and insect pest control measures were carried out as and when required. For the record of various observations five plants were selected at random form each treatment and labeled. Data so collected were subjected to statistical analysis[15].
RESULTS AND DISCUSSION
Maize-soybean intercropping
Plant height: Table 1 indicates that nitrogen treatments
exhibited significant effect on maize plant height. Highest nitrogen levels
of 120 kg ha-1 recorded maximum plant height of 212.00 cm in pure
stand followed by 209.50 and 209.25 cm in triple row arrangements and pure stand
planting, respectively. How ever, maize in pure stand gave comparatively greater
plant height than inter cropped treatments. Plant height under different intercropped
treatments showed non- significant differences. The plant height under treatment
I2 (paired) and I3 (triple) was 185.84 and 187.24 cm,
respectively. However, maize gave greater plant height (196.34 cm) in pure stand
(Table 2). Interactions of nitrogen levels x intercrop (F
x I) treatments were non-significant. Similar results were reported by Ahmed[16]
and Nizamani[17].
Number of leaves per plant: The results indicated that nitrogen levels significantly affected numbers of leaves maize per plant. At highest nitrogen dose (120 kg N ha-1) maximum number of leaves (11.80) per plant was recorded in paired row arrangement followed by 11.70 and 11.65 leaves per plant in pure stand and triple row planting, respectively (Table 1). The number of leaves per plant was not significantly affected under intercropped treatments (Table 2). The interaction of FxI was all not significant statistically. Similar results were reported by Herbert et al.[18].
Number of cobs per plant: Table 1 reveals that the number of cobs per plant of maize was not significantly affected by nitrogen levels as well as by intercropping treatments. The results further indicated that maize planted alone gave significantly greater (1.0) number of cobs per plant in all nitrogen treatments as compared to maize intercropped with soybean (0.95). The differences however, were statistically non significant. Application of nitrogen at higher level F2 (90 kg N ha-1) and F3 (120 kg N ha-1) in different planting patterns gave slightly greater number of cobs per plant as compared to lower nitrogen levels.
1000 grain weight of maize: The data present in the succeeding Table 1 revealed that nitrogen levels exhibited highly significant effect on 1000 grain weight in all planting patterns. All nitrogen treatments in different planting patterns gave significantly greater 1000 grain weight as compared to no fertilizer (Control) treatment. Increase in nitrogen level resulted in correspondence increase in 1000 grain weight. Maize 1000 grain weight was not significantly affected by intercropped treatments (Table 2). The interactions (F x I) were all non-significant statistically. Similar results were reported by Kalra and Ganger[13] and Nair et al.[7].
Grain yield (Kg ha-1): Table 1 revealed that nitrogen levels exhibited highly significant effect on grain yield of maize.
| Table 1: | Mean grain yield and yield components of maize intercropped with soybean under different planting patterns and nitrogen levels |
| *Significant**Highly significant NS. Non-significant | |
| Table 2: | Mean grain yield and yield parameters of maize alone and intercropped with soybean |
| * SignificantNS Non-significant | |
| Table 3: | Mean seed yield and yield parameters of soybean alone and as intercrop with maize |
| **Highly significantNS. Non-significant | |
Highest nitrogen levels of 120 kg ha-1 recorded maximum grain yield of 1694.75 kg ha¯1 in paired row arrangement, followed by 1694.25 kg ha-1in pure stand and 1687.50 kg ha-1 in triple row planting. The results of analysis of variance show that every increment in nitrogen level resulted in significant increase in grain yield. The results further indicate that grain yield of maize was not significantly affected by intercropped treatments, however, maize under mono-culture recorded greater grain yield (Table 2). The interaction of F x I were all non-significant statistically. The results are in agreement with the findings of Bahadur[8] and Singh et al.[5].
Intercrop (soybean)
Plant height: The data indicate that plant height was significantly
affected by intercropped treatments. Plant height in intercropped treatments
was adversely affected due to competition with main crop, mainly for light.
The maximum plant height (29.68 cm) was recorded in soybean alone. Plant height
in Intercrop treatment I2 and I 3 was 18.51 and 18.12
cm, respectively (Table 3).
Number of pods per plant: Table 3 revealed that number of pods per plant of soybean was significantly affected by intercropping treatments. Maximum number of pods (27.81) per plant was recorded in soybean alone and minimum 14.11 and 14.32 pods per plant were recorded in I2 and I3 intercropped treatments, respectively.
1000 seed weight of soybean: The results indicate that 1000 seed weight was not significantly affected by intercropping system. How ever, slightly higher seed weight was obtained in soybean planted alone as compared to soybean planted as intercrop. Maximum 1000 seed weight (171.06 g) was recoded from soybean alone followed by intercrop treatments I2 and I3 with 171.00 and 170.75 gm 1000 seed weight, respectively.
Soybean yield (Kg ha-1): Table 3 revealed that seed yield of soybean was significantly affected by cropping system. Significantly higher yield was obtained from soybean alone (1360.00 kg ha-1). While intercropped treatments show reduced yield i.e. 547.5 and 422.50 kg ha-1 in I2 and I3, respectively. The low yield in intercrop treatments may be mainly due to competition for light resulting in weak plant growth. Ahmed[16], Nizamani[17] reported similar results that legume yields were reduced by intercropping.