EFFECT OF DAYLENGTH ON THE GROWTH OF WHEAT

1967 ◽  
Vol 45 (1) ◽  
pp. 117-131 ◽  
Author(s):  
D. J. C. Friend ◽  
V. A. Helson ◽  
J. E. Fisher

Leaf area per plant, total number of leaves and tillers, and total plant dry weight increased with increasing daylength over the range 8 to 24 h. The increase in the net assimilation rate and relative growth rate with increasing daily total radiation was similar to that obtained by raising the intensity of light given to plants grown under continuous illumination.During the vegetative phase of growth, the leaf area ratio decreased with increasing daylength, mostly because of an increased leaf thickness, again dependent on the level of total daily radiation. During the later stages of growth, earlier floral initiation at long daylengths caused an early decline in the leaf area ratio because of the rapid growth of the stem associated with inflorescence formation. This was a photoperiodic effect independent of the level of total daily radiation, as shown by supplementing an 8-h daylength with 8 h of low-intensity illumination.

1988 ◽  
Vol 18 (1) ◽  
pp. 131-134
Author(s):  
Daniel K. Struve ◽  
W. Timothy Rhodus

The basal 1 cm of taproot of dormant bareroot 1-0 red oak (Quercusrubra L.) seedlings were given a 3-s dip in 20, 40, or 80 mM concentrations of indole-3-butyric acid (IBA), phenyl indole-3-thiolobutyrate (P-ITB), or equal parts IBA and P-ITB at 20 or 40 mM concentrations. Sixty control seedlings were dipped in 95% ethanol, while 30 seedlings were used for each auxin treatment. Seedlings were potted on May 12, 1986, and grown outdoors. At the end of the 104-day study period, all concentrations of IBA and P-ITB significantly increased number of roots regenerated (from 5.3 with 20 mM IBA to 11.9 for 80 mM IBA) compared with control seedlings. However, P-ITB-treated seedlings produced significantly more leaves (20–24) and leaf area (320–472 cm2), and up to 10 g more dry weight than IBA and non-auxin-treated seedlings. P-ITB treated seedlings had higher relative growth and net assimilation rates and lower leaf area ratio than IBA-treated or control seedlings. Seedlings treated with 20 mM of equal parts IBA and P-ITB were similar to P-ITB-treated seedlings while seedlings treated with the 40 mM IBA and P-ITB combination were similar to IBA-treated seedlings.


Author(s):  
Harun Özer ◽  
Mehtap Özbakır Özer ◽  
Ahmet Balkaya

This study were carried out to of different sowing time in order to determine the effects on plant growth of kohlrabi cultivation under Samsun condaitions during the autumn growing periods in unheated greenhouse. Four different seed sowing times (1st September, 15th September 1st October, 15th October), two different kohlrabi cultivars (Kolibri F1 and Korist F1) and two mulch applications (mulch covered and uncovered) were used in this study.The plant growth parameters analyzed (total plant dry weight, leaf area ratio, specific leaf area, net assimilation rate and relative growth rate) were found statistically significant (p<0.05). The highest total plant dry weight (114.1 g) was obtained from mulch application and 1st September seed sowing time. The highest leaf area ratio value were obtained in both mulch application the Kolibri F1 variety grown on October 15th. The highest net assimilation rate (0.65 g cm-2 day-1*1000) and relative growth rate (0.0090 g g day-1) were obtained from mulch covered plants grown in Kolibri varieties during September 1st. As a result, in this study higher dry matter accumulation was achieved by 1st September seed sowing times in vegetable growing in the last season in the greenhouse. In this way, the plants have successfully grown up and increased their productivity by entering the winter months, when the temperature and light intensity are decreasing.


Agronomy ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1859
Author(s):  
Saeid Hassanpour-bourkheili ◽  
Mahtab Heravi ◽  
Javid Gherekhloo ◽  
Ricardo Alcántara-de la Cruz ◽  
Rafael De Prado

Wild poinsettia (Euphorbia heterophylla L.) is a difficult-to-control weed in soybean production in Brazil that has developed resistance to herbicides, including acetolactate synthase inhibitors. We investigated the potential fitness cost associated to the Ser-653-Asn mutation that confers imazamox resistance in this weed. Plant height, leaf and stem dry weight, leaf area and seed production per plant as well as the growth indices of specific leaf area, leaf area ratio, relative growth rate and net assimilation in F2 homozygous resistant (R) and susceptible (S) wild poinsettia progenies were pairwise compared. S plants were superior in most of the traits studied. Plant heights for S and R biotypes, recorded at 95 days after planting (DAP), were 137 and 120 cm, respectively. Leaf areas were 742 and 1048 cm2 in the R and S biotypes, respectively. The dry weights of leaves and stems in the S plants were 30 and 35%, respectively, higher than in the R plants. In both biotypes, the leaves had a greater share in dry weight at early development stages, but from 50 DAP, the stem became the main contributor to the dry weight of the shoots. The R biotype produced 110 ± 4 seed plant−1, i.e., 12 ± 3% less seeds per plant than that of the S one (125 ± 7 seed plant−1). The growth indices leaf area ratio and specific leaf area were generally higher in the S biotype or similar between both biotypes; while the relative growth rate and net assimilation rate were punctually superior in the R biotype. These results demonstrate that the Ser-653-Asn mutation imposed a fitness cost in imazamox R wild poinsettia.


2017 ◽  
Vol 2 (1) ◽  
pp. 015
Author(s):  
Satiti Ratnasari ◽  
Eka Tarwaca Susila Putra ◽  
Didik Indradewa

Aluminum (Al) contained in acidic soil could become an obstacle for plant growth. The Al toxicity could inhibit root growth, water and nutrient absorption. One of the solution to overcome Al toxicity was by applying Silica (Si). The aim of this research was to study the impacts of Al to the growth activity of oil palm and to know the effects of Si to the growth activity of oil palm contaminated by Al. The factorial treatments were arranged in a complete random design with two factors. The first factor was Al toxicity, i.e. with and without Al, while the second factor was the application of Si that consisted of four levels (0, 32, 64, 96 gram per plant). some of variables included leaf area ratio (LAR), leaf area, net assimilation rate (NAR), relative growth ratio (RGR), plant height, and plant dry weight were observed. The result showed that Al toxicity decreased the LAR, leaf area, NAR, RGR, plant height, and plant dry weight. The application of Si 32 gram per plant increased leaf area ratio and was not significantly different from the application of 96 gram Si per plant. However, the application of Si to oil palm contaminated with Al did not affect to relative grow rate, but its application to normal plant would increase the relative growth ratio.


1958 ◽  
Vol 51 (3) ◽  
pp. 347-352 ◽  
Author(s):  
R. H. M. Langer

1. Swards of S. 48 timothy and S. 215 meadow fescue growing alone or together were sampled at intervals of 3 weeks throughout the season. The number and weight of leaves, stems and ears were determined, and leaf area was estimated.2. Despite high rainfall, the total number of tillers in both species declined from the beginning of the experiment until early July, but increased again from then onwards until the original complement had been approximately restored. The number of leaves failed to show a corresponding increase in the autumn because each tiller carried fewer leaves than earlier in the year.3. In the spring total dry weight increased more rapidly in meadow fescue than in timothy which in turn out-yielded meadow fescue later in the season. Both species attained their greatest dry weight soon after ear emergence, a period which was marked by considerable crop growth and relative growth rates.4. Leaf area index reached a maximum before total dry weight had increased to its highest level, but then declined in both species. Meadow fescue differed from timothy by producing a second crop of foliage after the summer with a leaf area index of about 7. This second rise appeared to be due mainly to increased leaf size in contrast to timothy whose leaves became progressively smaller towards the end of the season.5. The differences in growth between the species discussed with reference to their dates of ear emergence which in this experiment differed by about 6 weeks.


2012 ◽  
Vol 30 (2) ◽  
pp. 317-325 ◽  
Author(s):  
R.C. Souza ◽  
A.C. Dias ◽  
M.R.A. Figueiredo ◽  
F.E.B. Obara ◽  
P.J Christoffoleti

The aim of this research paper was to compare the growth of D. ciliaris and D. nuda crabgrass species under non-competitive conditions. To this end, two experiments were conducted, one from March - July 2010 and the other from February - June 2011. The experimental design of both trials was completely randomized making a factorial (2 seasons x 2 species crabgrass x 12 evaluation periods) with four replications. Assessments began at 15 days after sowing (DAS), and repeated weekly until 92 DAS. The variables evaluated were total dry matter (roots+leaves+stems), leaf area, leaf number and tiller. The results were submitted to analysis of variance and the absolute growth rate, relative growth rate and leaf area ratio were calculated using the means, which were adjusted regression models. The crabgrass species were significantly different in leaf area, leaf number, tiller number and dry matter per plant. D. ciliaris for all variables was statistically higher than D. nuda. Regarding the speed at which the growth of the species occurred, the absolute growth rate and relative growth rate of D. ciliaris was also greater than D. nuda. In addition, D. ciliaris also had a lower leaf area ratio indicating greater efficiency in converting light energy into carbohydrates. It can be concluded that D. ciliaris has a higher growth rate in conditions where there is no limitation of nutrients and water availability in relation to D. nuda, mainly due to D. ciliaris have greater leaf area, number of leaves and dry matter accumulation per plant.


2020 ◽  
Vol 41 (6supl2) ◽  
pp. 2911-2922
Author(s):  
Miria Rosa Durigon ◽  
◽  
Joanei Cechin ◽  
Franciele Mariani ◽  
Gerarda Beatriz da Silva Pinto ◽  
...  

Plant growth analysis is useful for determining adequate management practices and exploring the maximum yield potential of cultivars or hybrids. Canola hybrids with resistance to herbicides have been studied and registered for Brazilian conditions, as they improve weed management in canola crops. This study evaluated the growth of canola hybrids resistant to triazine or imidazolinone herbicides compared to a sensitive hybrid. The experiment was conducted using a completely randomized design, with four replications, in a bifactorial scheme using three hybrids and six sampling times. The canola hybrids used were Hyola 571CL (resistant to imidazolinones), Hyola 555TT (resistant to triazines), and Hyola 61 (sensitive to both herbicides). Height, leaf area, and dry matter of roots, leaves, stems, and shoots of the plants were evaluated at 14, 28, 42, 56, 70, and 119 days after emergence (DAE). The physiological indices absolute growth rate, leaf area ratio, specific leaf area, and net assimilation rate were calculated, and yield indices evaluated. Compared to Hyola 61, the Hyola 555TT hybrid showed lower values of leaf dry matter at 70 DAE, absolute growth rate up to 56 DAE, and net assimilation rate at 14 and 28 DAE, and a higher leaf area ratio at 56 DAE, whereas the hybrid Hyola 571CL presented lower leaf area and lower leaf dry matter at 70 DAE. At flowering, compared to Hyola 61, the hybrid Hyola 571CL presents lower leaf area, and the hybrids Hyola 555TT and Hyola 571CL have lower leaf dry matter accumulation. Differences in the growth of canola hybrids Hyola 555TT, Hyola 571CL and Hyola 61 do not cause differences in their grain yield.


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