Factors affecting seed and seedling vigour
Factors affecting seed and seedling vigour
Seed vigour is a term encompassing the sum total of those properties of the seed that determine the potential performance of the seed or seed lot during germination and seedling emergence (Perry, 1978). Rapid and uniform germination are among the properties of vigorous seeds (Argerish & Bradford, 1989). Low vigour adversely affects such factors as optimal emergence, stress resistance and uniform growth of emergent seedlings (Patrick et al, 2000) and is thus of great economic importance. Seeds, which grow well under the ideal conditions of the germination test, often do not perform so well when planted under the more stressful conditions of the field. Some seedlots perform particularly badly under stress, and are said to be of low vigour. A considerable amount of research has been carried out to discover the causes of low vigour, since if it could be prevented, fewer low-vigour seedlots would need to be wasted (pers.comm. Dr. A. Goldsworthy, 2003). Unfortunately, there does not seems to be a single underlying cause.
Seeds which are either smaller or larger than normal, are often of low vigour. Sawan et al (1999) found that both seed size and seed density are correlated with seedling vigour in cotton. Small seeds may lack food reserves, and large seeds may be more easily damaged by harvesting or have metabolic abnormality. These can be removed from an otherwise healthy seedlot by seiving. The seedling characteristics most closely associated with lower seedling vigour are a small embryo, small primary leaves on the main shoot, a low leaf area to leaf weight ratio, and a low frequency of coleoptile tillers (Richards & Lukacs, 2002).
Sometimes low vigour seeds have a low protein content. This may be due to inadequate nitrogen fertilisation. Application of more nitrogen will remedy this problem (Sawan et al, 1999).
Most cases of low vigour are due to seed damage (pers.comm. Dr. A.Goldsworthy, 2003). Seeds can be damaged in a
Seed vigour is a term encompassing the sum total of those properties of the seed that determine the potential performance of the seed or seed lot during germination and seedling emergence (Perry, 1978). Rapid and uniform germination are among the properties of vigorous seeds (Argerish & Bradford, 1989). Low vigour adversely affects such factors as optimal emergence, stress resistance and uniform growth of emergent seedlings (Patrick et al, 2000) and is thus of great economic importance. Seeds, which grow well under the ideal conditions of the germination test, often do not perform so well when planted under the more stressful conditions of the field. Some seedlots perform particularly badly under stress, and are said to be of low vigour. A considerable amount of research has been carried out to discover the causes of low vigour, since if it could be prevented, fewer low-vigour seedlots would need to be wasted (pers.comm. Dr. A. Goldsworthy, 2003). Unfortunately, there does not seems to be a single underlying cause.
Seeds which are either smaller or larger than normal, are often of low vigour. Sawan et al (1999) found that both seed size and seed density are correlated with seedling vigour in cotton. Small seeds may lack food reserves, and large seeds may be more easily damaged by harvesting or have metabolic abnormality. These can be removed from an otherwise healthy seedlot by seiving. The seedling characteristics most closely associated with lower seedling vigour are a small embryo, small primary leaves on the main shoot, a low leaf area to leaf weight ratio, and a low frequency of coleoptile tillers (Richards & Lukacs, 2002).
Sometimes low vigour seeds have a low protein content. This may be due to inadequate nitrogen fertilisation. Application of more nitrogen will remedy this problem (Sawan et al, 1999).
Most cases of low vigour are due to seed damage (pers.comm. Dr. A.Goldsworthy, 2003). Seeds can be damaged in a
References: Abba, E.J. and Lovato, A (1999) Effect of seed storage temperature and relative humidity on maize seed viability and vigour Argerish, C.A. and Bradford, K.J. (1989) The effects of priming and ageing on seed vigour in tomato Bradbeer, J.W. (1988) Seed Dormancy and Germination. Chapman and Hall, New York. Grass, L. and Tourkmani, M. (1999) Mechanical damage assessment in rejected durum wheat seed lots in Morocco Gupta, M. and Kashy, A.P. (1995) Phosphine fumigation against pulse beetle - germination and vigour of green gram seed Kozlowski, T.Z. (1972) Seed Biology (Vol. I). Academic Press, London. McCue, P., Zheng, Z., Pinkham, J.L. and Shetty, K. (2000). A model for enhanced pea seedling vigour following low pH and salicylic acid treatments Perry, D.A. (1978) Report on the vigour test committee 1974-7. Seed Science Technology, 6, 159-181. Richards, R.A. and Lukacs, Z (2002) Seedling vigour in wheat-sources of variation for genetic and agronomic improvement Sawan, Z.M., Gregg, B.R. and Yousef, S.E. (1999) Effect of phosphorus, chelated zinc and calcium on cotton seed yield, viability and seedling vigour