The Effects Of Heat Treatment On Seed Germination Biology Essay


Seed sprouting has been found to be influenced by many factors.

Some of these include H2O handiness, foods, visible radiation, incubation, and heat daze ( Masamba, 1994 ) . In the natural Western Australian environment, heat daze is most normally provided by bushfires. Periodic fires consequence in an unfastened environment supplying enhanced wet, visible radiation, and foods which are contributing to the endurance of germinated seeds ( Bell, Plummer, & A ; Taylor, 1993 ) . There are many species of the Western Australian vegetation, particularly in the Leguminosae households, that have a hardened episperm in order to stamp down sprouting until fire provides a better opportunity of seedling endurance ( Herranz, Ferrandis, & A ; Martinez-Sanchez, 1998 ) .

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Heat daze is required in some works species to fracture the difficult seed coat which allows for H2O imbibition, gas exchange, and releases the embryo from physical restraints ( Mucunguzi, & A ; Oryem-Origa, 1996 ) . Short exposures to the high temperatures reached in dirt during fires can greatly increase sprouting per centums of certain species ( Bell et al. , 1993 ) .Under research lab conditions, the heat daze normally provided by fire can be simulated utilizing boiling H2O. Dry heat or scarification and acerb interventions can besides increase the per centum of seeds germinated ( Bell et al. , 1993 ) . The purpose of the experiment was to analyze the effects of different temperature heat interventions on the per centum sprouting of four species of leguminous plants.

Materials and Methods

Plant MaterialFour different commercially obtained works species were used to analyze the effects of different heat pre-treatments on the per centum seed sprouting of set sample sizes. The four species used in the experiment were Kenndia coccinea, Acacia saligna, Hardenbergia, and Acacia pulchella.Experimental TreatmentA sum of 600 seeds were taken from each species and divided into sets of 110. Each set was pre-treated at one of five temperatures. The temperatures were: room temperature ( 24EsC ) , 40EsC, 60EsC, 80EsC, and 100EsC. The seeds from each intervention were divided into 50 labeled petri dishes, 11 seeds per dish.

All of the seeds in a individual petri dish underwent the same pre-treatment. The petri dishes were so placed into a dark closet for incubation at room temperature and randomized.Viability TestIn order to measure the viability of the seeds aggregations used for the sprouting experiment, a tetrazolium trial was carried out on 96 untreated seeds from each species.

The episperm of each seed was cracked before being tested.Scoring GerminationThe Numberss of seeds germinated in each petri dish were recorded at the terminal of each hebdomad for four hebdomads, along with the species and pre-treatment the seeds underwent. A bead of antifungal was used to kill any molds that were found turning in the petri dishes during incubation.Statistical AnalysisThe heat interventions of each species were compared utilizing the qi square analysis, leting for 5 % mistake.

The void hypothesis ( Ho ) for the qi square trials is that the interventions had no consequence on the per centum of seeds germinated. The alternate hypothesis ( Ha ) is that the different interventions did hold an consequence on the per centum of seeds germinated.


The qi square analysis compares the entire figure of germinated seeds between interventions for one species to find if statistically, we should accept or reject the void hypothesis.

Table 1 shows that Kenndia coccinea, Acacia saligna, and Acacia pulchella all have a qi square value greater that the 5 % mistake value. Therefore, we can be 95 % confident that the Ho should be rejected and Ha accepted. Hardenbergia, nevertheless, has a qi square value less than the 5 % mistake value, hence, Ho is accepted.Table 1 Chi square values and grades of freedom calculated from the figure of germinated seeds of four different works species after a assortment of controlled heat interventionsSpeciess Chi Square value 5 % mistakeKenndia Coccinea 52.90909 9.

49Acacia saligna 39.84615 9.49Hardenbergia 6.15444 9.49Acacia pulchella 38.5 9.49Data shows that three of the four qi square values are greater than the 5 % mistake value.

This indicates that the void 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 interventions had small consequence on the per centum sprouting of degree Celsius ) Hardenbergia. Significant fluctuations can, nevertheless, be seen in the sprouting of the other three species. Attention should be drawn to the important addition in sprouting of vitamin D ) Acacia pulchella between the 80EsC intervention and 100EsC intervention.a ) B )degree Celsius ) vitamin D )Fig. 1 Percent sprouting of a ) Kenndia Coccinea, B ) Acacia saligna, degree Celsius ) Hardenbergia, and vitamin D ) Acacia pulchella at the terminal of a four hebdomad growing period. Each species had 500 seeds which were divided into five different heat pre-treatments.


Heat daze interventions have two primary effects on seeds that cease quiescence. Crack of the seed coat appears to be most common consequence of heat daze ; nevertheless, heat can besides be used to denature seed coat inhibitors ( Hanley, & A ; Lamont, 2000 ) .It is obvious from the information displayed in table 1 and figure 1 that temperature has a important consequence on the sprouting of Kenndia coccinea, Acacia saligna, and Acacia pulchella. In the natural environment, utmost temperatures on the dirt surface can be lethal to seeds ( Bell et al. , 1993 ) . Due to thermic diffusion, seeds below 6 to 8 centimeter may be excessively deep to hold their seed coats cracked ( Hanley, & A ; Lamont, 2000 ) . A.

pulchella has developed a relationship with emmets to maximize sprouting. The emmets bury the seeds at a deepness of about 4cm which is the deepness where heat incursion and temperature required to interrupt quiescence appears to meet ( Hanley, & A ; Lamont, 2000 ) .A similar heat pre-treatment experiment ( Table 2 ) to the one carried out in this study was carried out by Bell, Plummer, & A ; Taylor ( 1993 ) . They examined the effects of seed scarification and boiling on the per centum sprouting of native Western Australian leguminous plants. The information indicates that a 300 2nd heat intervention tends to cut down sprouting per centums in most of the species listed in table 2. Acacia pulchella is one Western Australian species that shows no important sprouting in the per centum sprouting ( Bell et al. , 1993 ) .

This information suggests that A. pulchella evolved in an environment that experiences drawn-out combustion ( Bell et al. , 1993 ) .Table 2 Percent sprouting of Western Australian indigen leguminous plants subject to no pre-treatment, scarification, and boiling at assorted temperaturesTable 2 continuedThe consequences obtained by Bell, Plummer, & A ; Taylor ( 1993 ) after analyzing the effects of no pre-treatment ‘s, seed scarification, and heat daze on 55 species of native Western Australian leguminous plants.It is interesting to observe that the per centum sprouting graph of A. saligna in figure 1 shows an addition in sprouting as intervention temperature increased. This consequence is important as A.

saligna is a coastal home ground species whose seeds have the capacity to last mild fires, but are unable to digest intense heat ( Herranz et al. , 1998 ) .While high temperatures are required to check the seed coat of many native Western Australian species, sprouting may besides be cued by incubation temperatures that would outdo support the endurance of the seedlings ( Bell et al. , 1993 ) . It is possible that this factor may hold influenced the sprouting consequences of K. coccinea, A. saligna, Hardenbergia, and A. pulchella.

In Western Australia, heat is a cardinal demand for the successful sprouting of many works species. Combinations of factors, nevertheless, are frequently required to maximize the opportunity of sprouting of any works species. Due to the diverseness of vegetation in Western Australia, more research is required to find the optimum environment for commercial or private cultivation of many species.


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