Document Type : Research Paper
Authors
1 Hakim Farabi agro-industry CO, in Khuzestan, Khuzestan, Iran
2 Sugarcane development and by-products research and training institute, Khuzestan, Iran
3 Mirza Kochuk Khan Agro-Industry CO., Khuzestan, Iran
Abstract
Keywords
Main Subjects
Comparison of phosphorus uptake efficiency and effective mechanisms in commercial varieties of sugarcane
EXTENDED ABSTRACT
A great proportion of phosphorus (P) is in sparingly soluble and insoluble forms and small portion of P is accessible for crops in the form of available P ion in the soil solution. Low mobility of P in the soil is resulted from high reactivity of P with soil components, which causes strong retention of P. One of the strategies of using low-soluble and insoluble P components in the soil is selection and cultivation of plants and varieties with high P uptake efficiency. Knowledge about P uptake efficiency plays an important role in the management of P fertilizer consumption.
According to the necessity of P uptake efficiency knowledge, a pot experiment was carried out in greenhouse condition in Hakim Farabi Agro-Industry CO. that follows objectives including (1) to compare the P uptake efficiency in commercial sugarcane varieties, (2) to investigate the P uptake behavior in commercial sugarcane varieties under different levels of P fertilizer application, and (3) to evaluate the effective mechanisms on P uptake efficiency in commercial sugarcane varieties.
The treatments were P fertilizer (including: blank (P0), 125 (P50) and 250 (P100) kg ha-1 as triple superphosphate) and varieties of sugarcane (including: CP57-614, CP69-1062 and CP48-103) in three sampling times (including: 45, 90 and 130 days after planting) with three replications in factorial based on completely randomized design. Two single-bud sets of sugarcane (from each variety) were planted and then thinned to one plant per pot after 14 days. During growing period, soil moisture content was maintained at around 70% of field capacity (FC). At each sampling time, whole aboveground parts of sugarcane were harvested and the pots were completely emptied in order root sampling. In this study, P uptake, root length, specific root length, root to shoot ratio and P influx were evaluated at each sampling time.
In low available P condition, the CP48 and the CP57 varieties able to uptake more P and then considered as efficient P varieties. In CP48 variety, P uptake was increased by 13% and 45% compared to CP57 and CP69 varieties respectively, and CP57 showed enhancement of P uptake up to 29% compared to CP69 variety. Phosphorus influx decreased in CP57 and CP69 varieties by 53% and 67% respectively with aging of sugarcane that the greatest decrease of P influx was observed in CP69 variety. In the CP48 variety, P influx increased up to 66%, which can be an effective factor in more P uptake. While the CP69 variety showed a lower efficiency to uptake P. By the second sampling time, the root length and specific root length were greater in CP48 and CP57 varieties compared to CP69, and were considered as reasons for the higher P uptake in the first two varieties. In limited available P condition, exception the CP48 variety, P influx was diminished over time and it was greatest in the CP69 variety. Results showed that P uptake in CP69 was depended to the root length and the influx had lower importance. Therefore, influx was the main mechanism of P uptake in the CP48 variety. In the CP57 variety, both root length and influx were effective in P uptake. Phosphorus uptake in the CP69 variety enhanced when P fertilizer increased. In this condition, influx was effective mechanism on p uptake in the CP57. This indicated that the CP69 variety was suitable for fertilization. Therefore, these differences in the ability of P uptake in sugarcane varieties and mechanisms affecting P uptake can improve the management of P fertilizer consumption.
As a result, the CP48 variety has high efficiency in P uptake, the CP57 variety has a moderate efficient in P uptake and the CP69 variety does not have any efficient in P uptake.