scholarly journals Applications of Different Light Spectra in Growing Forest Tree Seedlings

Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1194
Author(s):  
Johanna Riikonen

Light intensity, duration and wavelength distribution are amongst the most important factors affecting the success of plant production in different cultivation systems [...]

1959 ◽  
Vol 7 (3) ◽  
pp. 268 ◽  
Author(s):  
RL Bieleski

The effect of various light intensities on the growth of kauri seedlings is described. Daylight was screened to the required level with lath screens. There was no significant effect of light on seedling mortality in the light intensity range 0.40–0.02 full daylight. Seedling morphology was affected by light intensity, the ratios stem dry weight/root dry weight, stem length/root length, and fresh weight / dry weight increasing significantly with decreasing light intensity. Seedling growth was a linear function of log (light intensity), the growth rates and assimilation rates being similar to those for other forest tree seedlings. The compensation point was at 0.009 full daylight, close to the low light intensity limit to seedling establishment in the field but low compared with those of other tree seedlings. There was no high light intensity limit to seedling growth, such as that shown for seedling establishment in the field. The apparent discrepancy is discussed.


2019 ◽  
Vol 73 (2) ◽  
pp. 120-122
Author(s):  
Naoki Negishi ◽  
Katsuhiko Nakahama ◽  
Nobuyuki Urata ◽  
Toshiaki Tanabe

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tomohiro Fujita

AbstractThis study examined the mechanisms of facilitation and importance of seed dispersal during establishment of forest tree species in an Afrotropical woodland. Seedling survival of Syzygium guineense ssp. afromontanum was monitored for 2.5 years at four different microsites in savannah woodland in Malawi (southeastern Africa) under Ficus natalensis (a potential nurse plant), Brachystegia floribunda (a woodland tree), Uapaca kirkiana (a woodland tree), and at a treeless site. The number of naturally established forest tree seedlings in the woodland was also counted. Additionally, S. guineense ssp. afromontanum seed deposition was monitored at the four microsites. Insect damage (9% of the total cause of mortality) and trampling by ungulates (1%) had limited impact on seedling survival in this area. Fire (43%) was found to be the most important cause of seedling mortality and fire induced mortality was especially high under U. kirkiana (74%) and at treeless site (51%). The rate was comparatively low under F. natalensis (4%) and B. floribunda (23%), where fire is thought to be inhibited due to the lack of light-demanding C4 grasses. Consequently, seedling survival under F. natalensis and B. floribunda was higher compared with the other two microsites. The seedling survival rate was similar under F. natalensis (57%) and B. floribunda (59%). However, only a few S. guineense ssp. afromontanum seedlings naturally established under B. floribunda (25/285) whereas many seedlings established under F. natalensis (146/285). These findings indicate that the facilitative mechanism of fire suppression is not the only factor affecting establishment. The seed deposition investigation revealed that most of the seeds (85%) were deposited under F. natalensis. As such, these findings suggest that in addition to fire suppression, dispersal limitations also play a role in forest-savannah dynamics in this region, especially at the community level.


1990 ◽  
Vol 41 (6) ◽  
pp. 1093 ◽  
Author(s):  
JL Wheeler ◽  
C Mulcahy ◽  
JJ Walcott ◽  
GG Rapp

The effect of seven factors, namely genotype, plant maturity, nitrogen fertilizer, phosphorus fertilizer, water stress, light intensity and temperature, on the hydrogen cyanide potential (HCNp) of forage sorghum was studied in three pot experiments. Fivefold differences occurred between genotypes in HCNp, with a breeder's line, X45106, selected for low HCNp having a maximum of 520 mg HCN kg-1 DM (dry matter) compared with 2300 and 2450 mg kg-1 DM for cvs Zulu and Silk respectively. In X45 106, HCNp (mg HCN kg-1 DM) declined curvilinearly with age d (days from sowing) (HCNp=8460- 320d+ 3.1d2) and linearly in Silk (HCNp = 9020 - 110d), but the decline in Zulu was not statistically significant. Nitrogen (equivalent to 200 kg ha-1 of N) increased HCN, (P< 0.001), but more so in full light (100 mg kg-1 compared with 1430 mg kg-1) than in 50% shade (190 mg kg-1 compared with 690 mg kg-1). In one experiment, acute water stress appeared to reduce HCNp, but this was confounded with the strong decline due to aging. In another study, acute water stress had no effect on HCNp. Neither the application of superphosphate nor change in light intensity, nor change in temperature had a direct significant effect on HCNp in these studies. Breeding and selection for low HCNp appears a promising approach to ensuring that sorghum plants will provide non-toxic forage from an early stage of growth.


2020 ◽  
Vol 1 (1) ◽  
pp. 23-26
Author(s):  
Siti Zulaikha ◽  
Martaleli Bettiza ◽  
Nola Ritha

Data on the rainfall is compelling to study as it becomes one of the major factors affecting the weather in a certain region and various aspects of life as well. Generally, predicting rainfall is performed by analyzing data in the past in certain methods. Rainfall is prone to follow repeated pattern in sequence of time. The utilization of big data mining is expected to result in any valuable information that used to be unrevealed in the big data store. Some methods used in data mining are Apriori Algorithm and Improved Apriori Algorithm. Improved Apriori itself is to represent the database in the form of matrix to describe its relation in the database. Data used in this research is the rainfall factor in 2016 in Tanjungpinang city. Based on the test of Improved Apriori Algorithm, it was found out that the relation of the rainfall and weather factors utilizing 2 item sets, that is, if the temperature is low (24,0 - 26,0), the humidity is high (85 - 100), then the rainfall is mild. If the temperature is low (24,0 - 26,0), the light intensity is low (0 – 3), then the rainfall is heavy, and 3 item sets if the temperature is low (24,0 - 26,0), the humidity is high (85 - 100), the sun light intensity is low (0-3), then the rainfall is medium.


2017 ◽  
pp. 21 ◽  
Author(s):  
Javier Carmona-Jiménez ◽  
Gustavo Montejano-Zurita

The results of a phycofloristic study on three springs in the Huasteca Potosina region are presented; 67 species are reported. Floristic similarities and differences among the springsare analized, as well as the relationship between species and environmental factors. Microhabitas were defined in the springs as well as the principal algal asociations that characterize them. Light intensity and current velocity are the most important factors affecting the predominant growth forms present in this type of habitat.


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