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Seed invigoration to overcome dormancy in ash gourd (Benincasa hispida (Thunb.) Cogn.)
An experiment ‘Seed invigoration to overcome dormancy in ash gourd (Benincasa hispida (Thunb.) Cogn.),’ was conducted during 2014-2016 in the Department of Seed Science and Technology, College of Horticulture, Kerala Agricultural University (KAU), Vellanikkara, Thrissur, following a completely rando...
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| Awduron Eraill: | |
| Fformat: | Ph.D Thesis |
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Vellanikkara
Department of Seed Science and Technology, College of Horticulture
2016
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| Pynciau: |
| LEADER | 06061nam a22001697a 4500 | ||
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| 082 | |a 631.521 |b SHO/SE | ||
| 100 | |a Shobha K V | ||
| 245 | |a Seed invigoration to overcome dormancy in ash gourd (Benincasa hispida (Thunb.) Cogn.) | ||
| 260 | |a Vellanikkara |b Department of Seed Science and Technology, College of Horticulture |c 2016 | ||
| 300 | |a 127 pages | ||
| 502 | |a MSc | ||
| 520 | 3 | |a An experiment ‘Seed invigoration to overcome dormancy in ash gourd (Benincasa hispida (Thunb.) Cogn.),’ was conducted during 2014-2016 in the Department of Seed Science and Technology, College of Horticulture, Kerala Agricultural University (KAU), Vellanikkara, Thrissur, following a completely randomized design with 16 treatments and three replications. The experiment aimed to elucidate the effect of seed invigoration on dormancy in ash gourd, to ascertain the anatomical changes in seed coat on seed treatment and to assess the storage potential of treated seeds under ambient conditions. Seed invigoration was resorted to by soaking seeds of variety KAU Local in water (hydro priming) for 24 hours, thiourea (0.5%) for 24 hours, KNO3 (0.4%) for 24 hours, KNO3 (0.7%) for 24 hours, KH2PO4 (10-1 M) for 24 hours, vinegar (pH 3.7) for 2 hours, polyethylene glycol 6000 (-0.5 MPa) for 24 hours, salicylic acid (60 ppm) for 12 hours, salicylic acid (60 ppm) for 24 hours, kinetin (10 ppm) for 12 hours, kinetin (10 ppm) for 24 hours, CaCl2 (50 mM) for 12 hours, CaCl2 (50 mM) for 24 hours, Psuedomonas fluorescens (1x106 cfu.ml-1) for 12 hours, Psuedomonas fluorescens (1x106 cfu.ml-1 ) for 24 hours. Untreated seeds served as control (T16). Both treated and untreated seeds, dried to < 8 per cent moisture content were packed in polythene bags (400 guage) and stored under ambient conditions upto ten months. The seed quality parameters viz., germination, germination index, coefficient of velocity of germination, energy of germination, mean time to germination, vigour indices I and II, and electrical conductivity of seed leachate were recorded at monthly intervals during storage. Seed microflora as well as histochemical studies to analyse the changes occurring in the dimensions of embryo and proportions of different fractions of seed coat were assessed at bimonthly intervals. Results pointed out the existence of significant differences in the impact of various invigoration treatments on the seed quality and histochemical parameters observed both within 35 days of invigoration as well as during storage. Majority of the seed invigoration treatments were effective in breaking dormancy in ash gourd. Dormancy was first broken in seeds treated with KH2PO4 and kinetin. In the above treatments germination reached above 60 per cent (the minimum standards for seed certification (MSCS) prescribed for ash gourd) on the 11th day after invigoration (DAI). Dormancy in untreated seed was broken only on the 35th day after extraction. However, seed invigoration with salicylic acid, vinegar and PEG 6000, proved to be detrimental. Seed invigoration also helped in extending the viability of seeds. Germination in seeds treated with CaCl2 for 24 hours, was found to be retained above MSCS for seven months during storage, whereas, in untreated seeds, germination above 60 per cent was observed for two months only. Seeds treated with salicylic acid failed to germinate by 35th DAI while those treated with vinegar and polyethylene glycol (PEG) failed to attain MSCS throughout the period of study. The viability of seeds treated with kinetin or CaCl2 for 12 hours and those treated with Pf for either 12 or 24 hours was found to be retained for six months of storage. Germination index, coefficient of velocity of germination, energy of germination, vigour indices I and II in both treated and untreated seeds, increased by 35th DAI and marginally decreased over the period of storage. In all the invigoration treatments, the above mentioned parameters were invariably higher than that of untreated control. However, the performance of seeds treated with salicylic acid, vinegar and PEG 6000 was lower than the untreated seeds. Invariably, the germination index, coefficient of velocity of germination, energy of germination, vigour indices I and II were high in seeds treated with CaCl2 for 24 hours followed by treatment with Pf for 12 hours and CaCl2 for 12 hours. The mean time to germination, electrical conductivity of seed leachate, the thickness of seed coat and its component layers as well as the microbial infection of seed was also observed to be low in these treatments. High and significant positive correlation was found to exist between germination and speed of germination, coefficient of velocity of germination, vigour indices I and II. It became evident that germination in ash gourd will be strongly affected with an increase in thickness of total seed coat or its outer layerthe testa. The thickening of seed coat owing to the thickening of testa will be accompanied with an obvious decrease in germination, germination index and coefficient of velocity of germination, vigour indices I and II. Results thus indicated that poor germination in seeds of ash gourd may be due to water impermeable seed coat (physical dormancy) mainly resulting from thickening of the outer layer (testa). Such dormancy in ash gourd can be best overcome by seed invigoration with CaCl2 (50 mM) for 24 hours. In addition, enhancement of seed viability, seed quality and seedling performance over storage was also achieved. Seed treatment with CaCl2 (50 mM) or Psuedomonas fluorescens (1x106 cfu.ml-1), for 12 hours were found to be the next best to treatment with CaCl2 (50 mM) for 24 hours. Hence, these can also be recommended for breaking dormancy and maintaining high seed quality in ash gourd. | |
| 650 | |a Department of Seed Science and Technology | ||
| 700 | |a Rose Mary Francies (Guide) | ||
| 942 | |2 ddc |c TH | ||
| 999 | |c 154711 |d 154711 | ||
| 952 | |0 0 |1 0 |4 0 |6 631_521000000000000_SHOSE |7 1 |8 REF |9 153791 |a KAUCLV |b KAUCLV |c THESES |d 2017-02-09 |o 631.521 SHO/SE |p 173815 |r 2017-02-09 |y TH | ||