Sunday, March 31, 2019
Effects of Heat Treatment on Seed Germination
Effects of Heat Treatment on Seed sproutingIntroductionSeed sprouting has been found to be influenced by many an(prenominal) factors. Some of these include water availability, nutrients, light, incubation, and wake up rape (Masamba, 1994). In the natural horse opera Australian environment, cacoethes shock is most commonly provided by bushfires. Periodic fires result in an open environment providing enhanced moisture, light, and nutrients which be conducive to the survival of germinated sows (Bell, Plummer, Taylor, 1993). There are many species of the Western Australian flora, especially in the Leguminosae families, that have a hardened testa in order to suppress sprouting until fire provides a separate chance of seedling survival (Herranz, Ferrandis, Martinez-Sanchez, 1998).Heat shock is require in any(prenominal) plant species to fracture the hard seed coat which allows for water imbibition, fluid exchange, and releases the embryo from physical restraints (Mucunguzi, Oryem-Origa, 1996). Short exposures to the superior temperatures r apieceed in soil during fires nates greatly increase germination portionages of certain species (Bell et al., 1993).Under laboratory conditions, the mania shock usually provided by fire quite a little be simulated using boiling water. Dry change or scarification and acid interferences loafer also increase the percent of seeds germinated (Bell et al., 1993). The aim of the try was to take in the issue of different temperature heat treatments on the percent germination of four species of legumes.Materials and Methods specify MaterialFour different commercially obtained plant species were used to examine the ensnares of different heat pre-treatments on the percent seed germination of set sample sizes. The four species used in the experiment were Kenndia coccinea, Acacia saligna, Hardenbergia, and Acacia pulchella. observational TreatmentA total of 600 seeds were taken from each species and divided into sets of 110. individually set was pre-treated at angiotensin converting enzyme of five temperatures. The temperatures were room temperature (24C), 40C, 60C, 80C, and 100C. The seeds from each treatment were divided into 50 tagged petri dishes, 11 seeds per dish. All of the seeds in a single petri dish underwent the comparable pre-treatment. The petri dishes were then placed into a dark cupboard for incubation at room temperature and randomized.Viability TestIn order to assess the viability of the seeds collections used for the germination experiment, a tetrazolium test was carried out on 96 untreated seeds from each species. The testa of each seed was cracked before being tested. rack up GerminationThe itemises of seeds germinated in each petri dish were recorded at the end of each week for four weeks, along with the species and pre-treatment the seeds underwent. A drowse off of fungicide was used to kill any moulds that were found growing in the petri dishes during incubation .Statistical AnalysisThe heat treatments of each species were compared using the chi neat analysis, allowing for 5% error. The aught hypothesis (Ho) for the chi substantive tests is that the treatments had no effect on the percent of seeds germinated. The alternate hypothesis (Ha) is that the different treatments did have an effect on the percent of seeds germinated.ResultsThe chi square analysis compares the total scrap of germinated seeds between treatments for one species to determine if statistically, we should accept or reject the null hypothesis. knock back 1 displays that Kenndia coccinea, Acacia saligna, and Acacia pulchella all have a chi square value greater that the 5% error value. Therefore, we can be 95 % confident that the Ho should be rejected and Ha accepted. Hardenbergia, however, has a chi square value less than the 5% error value, therefore, Ho is accepted.Table 1 Chi square values and degrees of freedom calculated from the number of germinated seeds of four different plant species after a variety of controlled heat treatmentsSpecies Chi Square value 5% errorKenndia Coccinea 52.90909 9.49Acacia saligna 39.84615 9.49Hardenbergia 6.15444 9.49Acacia pulchella 38.5 9.49 data shows that three of the four chi square values are greater than the 5% error value. This indicates that the null hypothesis should be rejected for Kenndia coccinea, Acacia saligna, and Acacia pulchella. Therefore, Ha is accepted for these species.It is obvious from the graphs in figure 1 that the different heat treatments had little effect on the percent germination of c) Hardenbergia. Significant variations can, however, be seen in the germination of the other three species. Attention should be worn to the significant increase in germination of d) Acacia pulchella between the 80C treatment and 100C treatment.a) b)c) d)Fig. 1 Percent germination of a) Kenndia Coccinea, b) Acacia saligna, c) Hardenbergia, and d) Acacia pulchella at the end of a four week growth period. Each species had calciferol seeds which were divided into five different heat pre-treatments.DiscussionHeat shock treatments have two primary personal effects on seeds that cease dormancy. snap of the seed coat appears to be most common result of heat shock however, heat can also be used to change seed coat inhibitors (Hanley, Lamont, 2000).It is obvious from the information displayed in table 1 and figure 1 that temperature has a significant effect on the germination of Kenndia coccinea, Acacia saligna, and Acacia pulchella. In the natural environment, extreme temperatures on the soil surface can be lethal to seeds (Bell et al., 1993). cod to thermal diffusion, seeds below 6 to 8 cm whitethorn be too deep to have their seed coats cracked (Hanley, Lamont, 2000). A. pulchella has developed a relationship with ants to maximise germination. The ants bury the seeds at a depth of approximately 4cm which is the depth where heat penetration and temperature necessary to break dormanc y appears to converge (Hanley, Lamont, 2000).A similar heat pre-treatment experiment (Table 2) to the one carried out in this report was carried out by Bell, Plummer, Taylor (1993). They examined the effects of seed scarification and boiling on the percent germination of primordial Western Australian legumes. The data indicates that a 300 second heat treatment tends to reduce germination percentages in most of the species listed in table 2. Acacia pulchella is one Western Australian species that shows no significant germination in the percent germination (Bell et al., 1993). This information suggests that A. pulchella evolved in an environment that experiences prolonged burning (Bell et al., 1993).The results obtained by Bell, Plummer, Taylor (1993) after examining the effects of no pre-treatments, seed scarification, and heat shock on 55 species of native Western Australian legumes.It is interesting to note that the percent germination graph of A. saligna in figure 1 shows an i ncrease in germination as treatment temperature increased. This result is significant as A. saligna is a coastal habitat species whose seeds have the capacity to survive mild fires, further are unable to endure intense heat (Herranz et al., 1998).While high temperatures are required to crack the seed coat of many native Western Australian species, germination may also be cued by incubation temperatures that would best support the survival of the seedlings (Bell et al., 1993). It is possible that this factor may have influenced the germination results of K. coccinea, A. saligna, Hardenbergia, and A. pulchella.In Western Australia, heat is a see requirement for the successful germination of many plant species. Combinations of factors, however, are a great deal required to maximise the chance of germination of any plant species. Due to the diversity of flora in Western Australia, more research is required to determine the optimal environment for commercial or private finishing of m any species.