(go
to KOMUGI Home) (go
to WIS List) (go
to NO.71 Contents)
Results and
Discussion
The incorporation of wheat straw water extract has significant
inhibitory effect on germination of wheat seed (Table
1). At the
maximum water extract level (0.6%), the percent reduction in
germination was 39 compared to control. Similarly highly significant
decrease was recorded with the increasing concentration of wheat
straw extract on shoot and root growth of wheat crop. The percent
decreases in shoot and root growth at the maximum residue extract
were 51 and 62, respectively. The results of the findings clearly
show differential phytotoxicity of aqueous extract of wheat straw.
The reduced growth of wheat parameters in this experiment
demonstrated that water soluble toxins released from the residues or
produced by microorganisms during decomposition and thus affected the
crop growth.
McCalla and coworkers (McCalla and Haskins 1964; McCalla 1971;
McCalla and Norstadt 1974) did pioneer research on the wheat crop in
the eastern Nebrasks (USA) area. They showed that watersoluble
substances in crop residues reduced the germination and growth of
seedlings of wheat and other crops. They further stated that wheat
and other crops were shown to contain a number of phenolic acids and
the five most dominant ones were ferulic, p-coumaric, syringic,
vanillic and p-hydroxybenzoic acids. Phytotoxic plant residues can
serve for selective weed control (Putnam and DeFrank 1983).
It was also observed that root growth was affected more than the
shoot growth. The roots which were in continuous contact with
the straw extract were exposed to possible toxic compounds evolved
either through the process of leaching or microorganisms action upon
decomposition (Azmi and Alam 1989;
Waller et al 1987). Other workers have reported that plant residues
caused injury if the residues were in contact with or in the
immediate vicinity of plant roots (Rice 1984; Patrick 1971).
It would be concluded
from this study that wheat straw water extract has depressing effects
on the germination and growth of shoot and root of wheat crop.
References
Azmi AR and Alam SM (1989) Effect of some wild plant residues on
germination and growth of wheat cultivars. Cereal Res Comm (Hung)
17(1): 25-27.
Borner H (1960) Liberation of organic substances from higher plants
and their role in the soil sickness problem Bot Res 26: 293-424.
Garb S (1961) Differential growth inhibition produced by plants. Bot
Rev 27: 422-443.
Guenzi WD and McCalla TM (1962) Inhibition of germination and
seedling development by crop residues. Soil Sci Soc Am Proc 26:
456-458.
LeTourneau D, Failes D, Heggeness HG (1956) The effect of aqueous
extracts of plant tissue on germination of seeds and growth of
seedlings. Weed IV: 363-368.
McCalla TM (1971). Studies on phytotoxic substances from soil
micro-organisms and crop residues. In Biochemical Interactions Among
Plants. Nat Acad Sci U.S.A. Washington DC. 39-43.
McCalla TM and Haskins FA (1964) Phytotoxic substances from soil
micro-organisms and crop residues Bacterial Rev. 28: 181-207.
McCalla TM and Norstadt FA (1974) Toxicity problems in mulch tillage.
Agric Environ 1: 153-174.
Patrick AA (1971) Phytotoxic substances associated with the
decomposition in soil of plant residues Soil Sci 111: 13- 18.
Putnam AR and DeFrank J (1983) Use of phytotoxic plant residues for
selective weed control Crop Protect 2: 173-181.
Rice EL (1984) Allelopathy. Academic Press Orlando, Florida. 2nd
Edition 422 P.
Waller GR, Krenzer EG Jr, McPherson JK and McGown SR (1987)
Allelopathic compounds in soil from no tillage vs conventional
tillage in wheat production. Plant and Soil 98: 5-15.
<--Back
(go
to KOMUGI Home) (go
to WIS List) (go
to NO.71 Contents)