Research Article
Evaluation of Sugarcane Clones with Biological Nitrogen Fixation Endowment
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M.Z. Karim
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M. Fida Hasan
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M.A. Hossain
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A.B.M. Mafizur Rahman
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In Bangladesh the average yield of Sugarcane staggers around 50 t ha-1 in the mill-zone and about 36 t ha-1 in non mill-zone areas (Anonymous, 1996). Among the various causes of this poor management, which is in normal practice by the resource-poor farming community is considered responsible. Large scale diversion of fertilizers, supplied on credit to cane growers, often take place because of the obvious socio-economic condition of the farmer. Under such a situation, cultivation of BNF (biological nitrogen fixation)-endowed Sugarcane varieties, as developed in Brazil, appear to be highly remunerative.
Contrary to our common believe that the legumes can only fix nitrogen in their root nodules, it has lately been well documented that non legume like Sugarcane and rice can also benefit from the atmospheric nitrogen fixed through some bacteria of the genera Acetobacter and Herbaspirillum. Two endophytic bacteria viz. Acetobacter diazotrophicus and Herbaspirillum spp. are major contributors of nitrogen fixation in Sugarcane. Such has been found within the roots and arial tissue of Sugarcane (Boddey et al., 1995; Ruschel and Vose, 1977; Dobereiner et al., 1993).
Recent discovery that some Sugarcane varieties can obtain very large contribution of BNF under field conditions and the existence of aboundant population of endophytic diazotrops (Acetobacter diazotrophicus and Herbaspirillum spp.) in this crop has opened a new and potential avenues of research that may greatly benefit the resources-poor cane growers in Bangladesh.
Since the experiment was aimed at substainly reducing/minimizing usage of N-bearing commercial fertilizers. It has negative impact on the environment, rather it should receive priority attention as an environment-friendly approach for increasing Sugarcane productivity. Development of Sugarcane variety with BNF-capability has great economic significance in a country like Bangladesh, where poor cane growers hardly apply the recommended dose of urea to Sugarcane.
The field testing was carried out at Bangladesh Sugarcane Research Institute (BSRI) farm, Ishurdi, Pabna, Bangladesh, in the cropping seasons 1999-2000 and 2000-2001. During the maturity stage any retention of green foliage indicates a plants availability of nitrogen either from soil or other sources. Based on the above consideration, field evaluation was done for selection of 45 clones from different test stages and BSRI germplasm bank. These clones were planted in the field under zero-N input condition. Other inputs such as P and K were applied as TSP, MP @ 277 kg ha-1 and S as gypsum @ 185 kg ha-1. Standard cultural practices were followed as and when required. Data were recorded on different growth parameters viz., germination (%) at 45 days after plantation (DAP), tiller number at 120 DAP, stalk elongation rate at June-July, visual foliage grading, number of millable cane and yield. Six clones viz., I 153/94, I 87/93, CO 846, I 197/93, Isd 28 and B 34-104 out of these 45 clones, showed better performance in first year (1999-2000) field testing.
So these 6 clones were selected as BNF-endowed clones for next year (2000-2001) field trail and planted under two field conditions such as zero-N and 120 kg N ha-1. In the second year, data were collected, as like as 1st year trial, but leaf nitrogen (N2) content was determined at 120 and 200 DAP by using modified Kjeldahl method (Jackson, 1973). By this trail only four clones (I 153/94, Co846, B 34-104 and Isd 28) were selected as BNF-endowed clones.
Endophytic diazotrophs like Acetobacter diazotrophicus fix atmospheric N2 in Sugarcane (Faente et al., 1993; Li and Macre, 1992). Acetobacter diazotrophicus was found to colonize extensively the exterior and interior of shoot and root (James et al., 1994). Based on these reports bacteria were tried to isolate in this research work, from the root extract and cane juice of these clones. For this work, root tip extract and cane juice were cultured aseptically on the bacterial culture medium and incubated at 26°C for 72 h. Both root extract and cane juice showed bacterial growth on the medium. The nature of the growing bacteria was tested as gram negative.
Data on different parameters were subjected to statistical analysis and mean values were compared using LSD at 5% level of significant (Gomez and Gomez, 1984).
In the first year field trail six clones, I 153/94, I 87/93, Co 846, I 197/93, Isd 28 and B 34-104 at zero-N input condition showed better performances (Table 1). After 45 days of plantation the highest germination (70.83%) was recorded from the clone Isd 28 followed by clone I 197/93 (61%), while the lowest germination (48.66%) was recorded from B 34-104. At 120 DAP the highest number of tiller (87.30x103 ha-1) was recorded from clone I 153/94 while the lowest (65.00x103 ha-1) from clone I 87/93. From the foliage grading, it was observed that clones which were better in tillering, showed deep green in foliage colour. Stalk elongation rate was higher (2.02 cm day-1) in Co 846 followed by I 153/94 (1.76 cm day-1) at June-July. The highest number (75.22x103 ha-1) of millable cane was recorded from Isd 28 followed by I 153/94 (72.00x103 ha-1) and the lowest (62.30x103 ha-1) was recorded from I 87/93. After harvest, the highest cane yield (63.50 t ha-1) was recorded in Isd 28 followed by Co 846 (62.70 t ha-1) and the lowest yield (49.24 t ha-1) showed by I 87/94. On the basis of these results Co 846, Isd 28, I 153/94 and B 34-104 were selected as possible BNF-endowed clones.
From the 2nd year field trail possible BNF-endowed clones (I 153/94, Co 846, B 34-104 and Isd 28) at zero-N and 120 kg N ha ha¯1 input conditions showed that highest tiller number, 85.80x103 ha-1 was recorded at zero-N by the clone Isd 28 while at 120 kg N ha-1, it was 88.98x103 ha-1; followed by I 153/94 (84.60x103 ha-1 at zero-N and 85.50x103 ha-1 at 120 kg N ha-1). The lowest number of tiller, 78.90x103 ha-1 at zero-N and 80.57x103 ha-1 at 120 kg N ha-1 was recorded by the clone Co 846. Table 2 further indicated that the non BNF clone Isd 18 produced less (50.35x103 ha-1) tiller, it was the lowest of all the test clones at zero-N, but at 120 kg N ha-1 it was the highest (90.82x103 ha-1) obtained from the clone Isd 2/54 (non BNF). The possible BNF-endowed clones respond similarly in tiller production and showed less significant difference, but possible non BNF clones showed significant difference in tiller production at zero-N and 120 kg N ha-1 input conditions. (Table 2)
Table 1: | Performance of BNF possible clones (1st field trail) at zero-N input condition |
1: Visual grading was clone on the basis of foliage colour, **: Normal green, ***: Deep green |
Table 2: | Performance of BNF-endowed clones at Zero-N input and 120 kg N ha-1 input condition |
Table 3: | Leaf nitrogen contents of Sugarcane clones grown under zero-N and 120 kg ha ha¯1 N level |
Millable cane indicated that the clone Isd 28 gave the highest number of millable cane of 69.20x103 ha-1 at zero-N and 71.22x103 ha-1 at 120 kg N ha-1 input condition followed by the clone I 153/94 (67.7x103 ha-1 at zero-N and 66.00x103 ha-1 at 120 kg N ha-1).
The lowest number of millable cane, 61.75x103 ha-1 at zero-N and 62.10x103 ha-1 at 120 kg N ha-1 shown by the clone Co 846, another BNF capable clone B 34-104 produced 63.17x103 ha-1 at zero-N and 64.33x103 ha-1 at 120 kg N ha-1 condition. The results showed less significant difference in millable stalks production at zero-N and 120 kg N ha-1 condition of BNF possible clones. In the same conditions Isd 2/54 (47.50x103 ha-1 at zero-N and 77.19x103 ha-1at 120 kg N ha-1) and Isd 18 (39.50x103 ha-1 at zero-N and 73.35x103 ha-1 at 120 kg N ha-1), the non BNF clones showed highly significant difference to produce millable cane.
The clone Isd 28 gave the highest cane yield 63.97 t ha-1 at zero-N and 70.59 t ha-1 at 120 kg N ha-1, while the clone B 34-104 produced the lowest cane yield 53.69 t ha-1 at zero-N and 57.15 t ha-1 at 120 kg N ha-1 input condition. (Table 2)
Second highest yield 61.48 t ha-1 at zero-N and 65.75 t ha-1 at 120 kg N ha-1 input condition from the clone Co 846. BNF possible another clone I 153/94 showed 54.30 t ha-1 cane yield at zero-N and 59.72 t ha-1 at 120 kg N ha-1 condition, respectively. The yield results of all the test clones showed significantly different at zero-N and at 120 kg N ha-1 condition. But these clones produced higher cane yield (53.56 63.97 t ha-1) at zero-N input condition than the average cane yield (36 t ha-1 at non mill zone and 50 t ha-1 at mill zone area) of Bangladesh. From these, we assume that selected clones can fix/earn 120 kg N ha-1. Boddey et al, (1991) reported that some of the Brazilian Sugarcane varieties could fix 150 kg ha-1 N fertilizer. Stanford and Ayres (1964) reported that a Sugarcane crop yielding 100 t cane ha-1 accumulates between 180 and 250 kg N ha-1.
At two times (120 and 200 DAP) leaf nitrogen contents of these clones which grown under zero-N and 120 kg N ha ha¯1 level showed that highest (1.85%) leaf nitrogen content at 120 DAP of clone I 153/94 but nitrogen content at 120 kg N ha ha¯1 condition at the same times was 1.91%. But at 200 DAP, leaf nitrogen content was decreased, (1.36%) under zero-N and 1.41% at 120 kg N ha-1 condition. At 120 DAP of clone B 34-104 showed similar (1.66%) leaf nitrogen content at zero-N and 120 kg N ha-1 condition. It was 1.31% at zero-N and 1.26% at 120 kg N ha-1 at 200 DAP. Leaf nitrogen of all the clones were decreased from 120 DAP to 200 DAP. A non BNF possible clone Isd 18 at 120 DAP showed 1.20% leaf nitrogen at zero-N and 1.73% at 120 kg N ha-1, here nitrogen percentage was highly different at zero-N to 120 kg N ha-1 condition than BNF possible clones. Leaf nitrogen of Isd 18 at 200 DAP was very low (0.68%) at zero-N but at 120 kg N ha-1, it was 1.32% (Table 3).
Cane juice of 2 BNF possible clones (I 153/94 and Co 846) showed the bacterial growth on the culture medium, other 2 (Isd 28 and B 34-104) clones juice did not show bacterial growth (Table 4). Root tip extract of all BNF possible test clones showed bacterial activities on the culture medium. This findings agreed with the report of James et al. (1994). Acetobacter diazotrophicus, the nitrogen fixing bacterium of Sugarcane is a gram negative . In this study, the nature of growing bacterium was tested that these were gram negative but the bacterium was not identified.
Table 4: | Screening bacterial activities in the cultured medium by the culture of aseptic cane juice and root tip extract |
+: Indicate presence of bacteria, -: Indicate absence of bacteria; N: no, Y: yes 1: Visual grading was done on the basis of foliage colour; **: Normal green; ***: Deep green |
Both cane juice and root tip extract of non BNF clones (Isd 2/54 and Isd 18) did not show any bacterial activities on the medium indicated that these 2 clones were unable to fix atmospheric nitrogen.
It could be concluded that the selected clones have some characteristics to fix nitrogen from the atmosphere. It may be alternative strategies for nitrogen supplementation of Sugarcane cultivation and can reduce the cost of input for N2 use.