Jan 5, 2012 - true potato seed, New Zealand Journal of Experimental Agriculture, 12:2, ... true potato seed; seed extraction; environmental .... Manila, Philip-.
New Zealand Journal of Experimental Agriculture
ISSN: 0301-5521 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/tnzc19
Extraction and germination of true potato seed D. T. P. Gallagher & M. N. Nabi To cite this article: D. T. P. Gallagher & M. N. Nabi (1984) Extraction and germination of true potato seed, New Zealand Journal of Experimental Agriculture, 12:2, 151-154, DOI: 10.1080/03015521.1984.10421425 To link to this article: https://doi.org/10.1080/03015521.1984.10421425
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New Zealand Journal of Experimental Agriculture. 1984. Vol. 12: 151-154 0301-5521/84/1202-0151$2.50/0 © Crown copyright 1984
151
Extraction and germination of true potato seed
D. T. P. GALLAGHER M. N. NABI Crop Research Division, DSIR Private Bag, Christchurch, New Zealand
Abstract The effects of temperature and extraction methods of potato seed from berries on the germination of potato seed from several families were tested. Hand extraction for seeds gave the best germination rates; however, if large quantities of seed were required the Waring blender was used for 10 s at low speed. The best germination percentages were obtained at 12 and 15°C. Keywords genotypes; seed germination; potatoes; true potato seed; seed extraction; environmental effects; enzymes; homogenisation
INTRODUCTION
Germination of true potato seed is known to be erratic ranging between 5 and 80% emergence. There is variability within families of the same genotype as well as between genotypes (Accatino 1979). During the development of true potato seed cultivars it became evident that both the method of seed extraction and germination conditions contributed to the erratic germination percentage. Two experiments were carried out to investigate the effect of seed extraction and germination conditions on germination.
MATERIAIS AND METHODS
Experiment 1 Three families which produce many berries, 72625, 1062-47, and 1053-11, bred at Crop Research Division, DSIR, were selected. Berries were collected from the field when they had reached maximum size. When berries began to tum from green
Received 21 November 1983; revision 20 February 1984
to fawn the seed was extracted. However, if the enzyme method of extraction was used the berries were allowed to tum fawn and become soft. 25 berries from each family were used for each extraction test. The following extraction tests were used: 1 Hand extraction. Once berries were soft, seed was extracted by squeezing the berry into water. Seed was then left under a gently running tap to clean. 2 Sorvall Omni mixer. Rubber flail blades were used for either 10 or 60 s, then the seed was cleaned as above. After the lOs treatment some hand work was required to complete the seed extraction. 3 Waring blender. Berries were blended with metal blades, at low speed for 5, 10, or 30 s. The seed dropped to the bottom of the blender and the debris was floated off under gently running water. 4 Enzyme. The Rohament P. cellulase enzyme was diluted to solutions of 1.5 and 2%. Berries have a 4.1 pH. Berries therefore fell in the 3.8-5.0 pH activity range and were squashed with a pestle and mortar. A mix of equal parts of pulp and enzyme was placed in a cabinet at 2YC and agitated for 2 hours. Seed was then washed under gently running water to clean away the pulp. Seed from all methods of extraction was left to dry overnight on paper towels before being put into airtight bottles. Both laboratory and glasshouse germination tests were conducted. Laboratory tests. Four replications, each of 100 seeds from each treatment and each family, were placed in petri dishes containing moistened filter paper. The dishes were placed in a dark cabinet at 10°C and germination was recorded weekly until the end of the third week. Glasshouse tests. Standard seed sowing methods were followed. Three replicates, of 1()() seeds of each treatment and each family, were sown in boxes filled with a standard potting mix and then covered with sand. Boxes were covered with glass and paper and put in a heated glasshouse - 2YC day/lYC night. Weekly germination counts were made for 4 weeks.
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Table 1 Mean germination counts of true potato seed from 3 families in laboratory petri dishes and boxes of soil in a glasshouse. Family 726-25
Extraction method Omni rubber lOs Omni rubber 30 s Hand Enzyme 1.5% Enzyme 2.0% Waring blender 5 s Waring blender 10 s Waring blender 30 s S. E. of mean Grand mean
1062-47
Soil
Petri dish
76.7 a l 82.3 a 82.0 a 58.0 b 63.7 b 52.7 b 63.0 b 38.3 c
81.0 ab 85.3 ab 90.3 a 78.0 be 67.5 d 69.5 cd 81.3 ab 85.0 ab
4.3 64.6
3.4 79.7
Soil 33.7 40.7 49.3 61.0 37.3 59.0 50.7 50.0
c be ab a c ab abc abe
5.7 47.7
1053-11
Petri dish 79.5 76.5 85.5 81.0 80.3 92.0 89.5 72.8
a a a a a a a a
5.3 82.1
Soil 61.0 63.3 60.7 46.0 45.7 58.0 60.3 48.7
a a a a a a a a
6.0 55.5
Petri dish 72.1 ab 39.9 d 74.0 ab 64.1 be 58.0 c 71.4 ab 70.4 ab 78.5 a 3.6 66.1
IMeans within each column with same letter not significant at 5%.
Experiment 2 Seed from 7 families, having very low or nil germination rates, and a family known to have very high germination rates in the seed boxes, were chosen for petri dish germination tests at different temperatures. Seeds were placed on moist filter paper in petri dishes in incubators, at 5, 10, 12, 15, 20 ± 2, and 25 ± 2°C. There were 3 replications of each family at each temperature. The first test consisted of 100 seeds and the subsequent replicates consisted of 20 seeds of each family. Germination was recorded daily for 4 weeks and germinated seeds were removed after counting. RESULTS AND DISCUSSION Experiment 1 The time required and ease of extraction varied between the 4 extraction methods. The Sorvall Omni mixer method was slow, because the extracting bowl was small, berries needed chopping up, and some handwork was required. Hand extraction of seed was quite satisfactory for small amounts. The enzyme extraction method was slow because the enzyme had to be prepared, the pH of the berries checked, and complete separation of the seed from the flesh took 2 hours. The Waring blender was the quickest method for the extraction oflarge amounts of seed unless the berries were blended for only 5 s. Handwork was still required after this short processing time. In general, germination in petri dishes was better than in soil, but results varied for each genotype and extraction method. There were also differences
in variability in each genotype and environment. Data for seed germination in soil and petri dishes of the different potato families are analysed separately. Means and standard errors of the means are given in Table I. Family 726-25. The percentage germination was generally the same in the petri dishes as in soil. However, in the soil germination test, the enzyme and Waring blender treatments produced mean germination counts that were significantly lower than for hand extraction. The Waring 30 s treatment gave a particularly low germination count. This low value could be due to damage to the seed coat which was more obvious within soil because of less favourable germination conditions (Simmonds 1963; Kunkel 1979; White & Sadik 1983; Bedi et al. 1979). The Waring blender at 10 and 30 s produced germination counts that were not significantly different from counts produced by hand extraction in the petri dishes. Family 1062-47. In soil, the coefficient of variation was higher than that for petri dish counts. Enzyme 2% extraction produced a germination count that was significantly lower than the enzyme 1.5% extraction. There was no significant difference between germination counts resulting from seed extracted by the various methods and germinated in petri dishes. Family 1053-11. Germination counts were lower in this family than in the other 2 families. The results were more variable because some of the petri dishes gave very low germination counts (0-8%). TlUs variability and low germination could not be accounted for. There were no significant differences
Gallagher & Nabi-Potato seed extraction and germination
153
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Fig. 1 Effect of temperatures on true potato seed germination. Vertical bars represent the standard errors of the mean percentages of seeds germinated at germination percentages of 10, 30, 50, 70, and 90. At other germination rates values are intermediate in size.
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New Zealand Journal of Experimental Agriculture, 1984, Vol. 12
between methods (CV = 39%). The data was analysed again omitting these low figures; the means of this data are in Table 1. The Omni rubber 30 s treatment gave a lower germination than Omni rubber 10 s. Damaged seed coats may explain this finding; however, this difference was not observed in soil germination or in the other families. Experiment 2 Results of the seed germination test at different temperatures are included in Fig. 1. The optimal temperature for germination was about 12-1 SOc. The rate of germination was lowest at SOC but increased with increasing temperatures up to 15°C. The rate of germination declined at the 2 higher temperatures - 20 and 25°C. A similar result was obtained by White & Sadik (1983). In 3 families the best germination percentage w.as 12°C, and for another 5 families it was lSOC. In 6 families there was no significant difference between germination percentages at 12 and 1SOC. Families 733-01 and 1068-42 were the only families to achieve a germination rate greater than 60%. In these 2 families the germination rate was significantly better at 15 than at 12°C.
CONCLUSIONS There are differences in germination percentages between: families; treatments; and laboratory and glasshouse environments. Hand extraction gives the best germination counts but, if extracting large quantities of seed, the Waring blender could be used for 10 s at low speed. Subsequent work has shown that a high temperature after sowing affects the germination percentage in some families. Temperatures around 12 to 15T appeared to be most suitable for the germination of true potato seed.
ACKNOWLEDGMENTS We are grateful to Dr A. Bedi and Mr R. Genet for the supply of true potato seeds; Dr H. C. Smith and Mr T. P. Palmer for their advice and· helpful discussion; Miss E. Stevenson for statistical analysis of extraction methods; and Mr A. Wallace for analysis of germination tests.
REFERENCES Accatino, P. 1979: Agronomic management in the utilization of true potato seed: preliminary results, pp. 61-99. In: Production of potatoes from true seed. Report of a planning conference. Manila, Philippines, September 13-15. International Potato Centre, Lima Peru. Bedi, A. S.; Smale, S.; Burrows, D. 1979: Experimental potato production in New Zealand from true seed, pp. 100-116. In: Production of potatoes from true seed. Report of a planning conference. Manila, Philippines, September 13-15. International Potato Centre, Lima, Peru. Kunkel, R. 1979: Physiological and agronomical constraints in the use of botanical potato seed in commercial potato production, pp. 29-35. In: production of potatoes from true seed. Report on a planning conference. Manila, Philippines, September 13-15. International Potato Centre, Lima, Peru. . Simmonds, N. W. 1963: Experiments on the germination of potato seeds. I. European potato journal 6: 4560. White, J. W.; Sadik, S. 1983: The effect of temperature on true potato seed germination, pp. 188-189. In: Research for the potato in the year 2000. Proceedings International Congress. International Potato Centre, Lima, Peru.
