Croissance et tubérisation du radis (Raphanus sativus) selon la durée d'éclairement

1988 ◽  
Vol 66 (9) ◽  
pp. 1834-1840 ◽  
Author(s):  
L. Combe ◽  
Ph. Quetin ◽  
G. Decoux

Radish tuberization was studied with plants grown in a controlled-environment room at 19 °C day and night, with a daily light duration (radiant flux density, 600 μmol m−2 s−1 photosynthetically active radiations (PAR)) varying from 4 to 24 h at 2 h intervals. Day length did not seem to play a role in the initiation of tuberization: tuber thickening began after about 50 h of cumulative light exposure for all treatments. Moreover, two light treatments with the same daily photosynthetic balance, 8 h a day at high saturating irradiance (600 μmol m−2 s−1 PAR) and 16 h a day at low irradiance (200 μmol m−2 s−1 PAR), resulted in the same growth and tuberization regardless of day length. When the photoperiod is shorter than 7 h, it can modify leaf area, but for longer photoperiods, age is the main criterion determining foliage area. Cumulative light exposure determines the tuber dry matter to foliage dry matter ratio (tuberization index) if the day length is shorter than 16 h; if it is not, plant age alone determines the tuberization index. Day length has an effect on radish tuberization essentially because of its trophic action by photo-synthetic assimilate allocation to tuber thickening.

1979 ◽  
Vol 59 (1) ◽  
pp. 81-85 ◽  
Author(s):  
S. FREYMAN ◽  
G. A. KEMP ◽  
D. B. WILSON

Growth and rates of photosynthesis of two accessions and two cultivars (Great Northern 1140 and Sutter Pink) of bean (Phaseolus vulgaris L.) were compared at 10, 15, and 23 °C in a controlled environment cabinet. The leaf area, dry matter, and rate of total apparent photosynthesis of one of the accessions was significantly higher after growth for 13 days at 10 °C than that of the commercial cultivars. This advantage was not maintained at 23 °C. In another experiment, growth of the same four cultivars was compared at light/dark temperatures of 10/10, 15/12, and 23/18 °C. The two accessions established a higher leaf area and accumulated more dry matter at the cooler temperatures than the commercial cultivars, but lost this advantage at the highest temperatures. In a field trial, the accessions had a similar rapid early growth but fell behind later in the season. Ideally, a bean cultivar for the Canadian prairie should incorporate the accession’s ability for rapid growth and leaf expansion at cool temperatures with a growth rate during mid-summer comparable to that of Great Northern 1140.


1991 ◽  
Vol 116 (3) ◽  
pp. 544-551 ◽  
Author(s):  
I.J. Warrington ◽  
R.A. Norton

Plants of chrysanthemum [Dendranthema × grandiflorum (Ramat.) Kitamura], radish (Raphanus sativus L.), corn (Zea mays L.), and cucumber (Cucumis sativus L.) were grown under 8-, 12-, 18- or 24-hour daylengths and at three photosynthetic photon fluxes (PPF) within each daylength to evaluate growth and development responses to daily quantum integral (PPF × duration). For the same daily quantum integral, dry matter accumulation and leaf area development were less under 24-hour than under 18-hour daylengths with chrysanthemum and radish. With corn and cucumber, these values were similar under 12-, 18-, and 24-hour daylengths. In all of the species, leaf area and dry matter development were lowest under the 8-hour daylength. Continuous (24-hour) daylength produced some growth abnormalities in radish and chrysanthemum. Specific leaf weight in all species and flower node count in cucumber were linearly related to daily quantum integral up to the highest values examined (73.5 mol·day-1·m-2). All species showed expected photoperiod responses with respect to flowering, but the rate of floral development and number of flower buds formed were highest under the highest PPF (and highest daily quantum integral) treatments. The results indicate that field phenotypes can be obtained in controlled environment (CE) conditions, providing the field daylength and daily quantum integral conditions are reproduced.


Weed Science ◽  
1993 ◽  
Vol 41 (4) ◽  
pp. 574-582 ◽  
Author(s):  
David T. Patterson

Sicklepod was grown in controlled-environment chambers in 16 day/night temperature regimes ranging from 19/11 to 34/26 C. Maximum dry weight, leaf area, plant height, node number, and leaf number after 46 d occurred at 29/26 and 34/26 C. Temperatures of 29/21 C or lower reduced dry weight by more than 50%. Leaf number, leaf weight, and leaf area were more sensitive to changes in day temperature, whereas plant height and root, stem, and total dry weight were more sensitive to night temperature. Dry matter production was more closely correlated with leaf area duration than with its other component, net assimilation rate. Leaf appearance rate and dry matter production were linearly related to average daily temperature. The low-temperature threshold for leaf production was 13 ± 1 C. Observations of plant development in photoperiods ranging from 10 to 16 h confirmed that sicklepod is a short-day plant with a critical day length of 13 to 14 h. No reproductive development occurred in photoperiods of 15 or 16 h. Seedlings that emerged in 10-h photoperiods required more than 1-wk exposure to short days to initiate and continue reproductive development. Plants from a North Carolina population flowered earlier than plants from a Florida population in photoperiods of 12, 13, or 14 h, but in an 11-h photoperiod the two populations flowered at the same time.


Helia ◽  
2001 ◽  
Vol 24 (35) ◽  
pp. 135-148
Author(s):  
Mohammed El Midaoui ◽  
Ahmed Talouizte ◽  
Benbella Mohamed ◽  
Serieys Hervé ◽  
Ait Houssa Abdelhadi ◽  
...  

SUMMARYAn experiment has been carried out in order to study the behaviour under mineral deficiency of three sunflower genotypes, a population variety (Oro 9) and two hybrids (Mirasol and Albena). Sunflower seedlings were submitted to five treatments: N deficiency (N0), P deficiency (P0), K deficiency (K0), N and K deficiency (N0K0) and a control. Plants were harvested when they reached 3-4 true pairs of leaves. Growth parameters measured (height, total leaf area, root length, root and shoot dry mater) were all significantly reduced by mineral deficiency. Leaf area was most reduced by N0 (-61%) and P0 (-56%). Total dry matter was most affected by N0 (-63%) and by N0K0 (-66%). Genotype comparisons showed that Oro 9 had the highest shoot dry matter while Albena had the lowest root dry matter. Effect of mineral deficiency on content and partitioning of N, P, K, Ca and Na was significant and varied according to treatments and among plant parts. Shoot dry weight was significantly correlated with root N content (r2=0.81) and root K content (r2=-0.61) for N0 and K0.


Author(s):  
Muhammad Zeeshan Mehmood ◽  
Ghulam Qadir ◽  
Obaid Afzal ◽  
Atta Mohi Ud Din ◽  
Muhammad Ali Raza ◽  
...  

AbstractSeveral biotic and abiotic stresses significantly decrease the biomass accumulation and seed yield of sesame crops under rainfed areas. However, plant growth regulators (such as Paclobutrazol) can improve the total dry matter and seed production of the sesame crop. The effects of the paclobutrazol application on dry matter accumulation and seed yield had not been studied before in sesame under rainfed conditions. Therefore, a two-year field study during 2018 and 2019 was conducted with key objectives to assess the impacts of paclobutrazol on leaf greenness, leaf area, total dry matter production and partitioning, seed shattering, and seed yield of sesame. Two sesame cultivars (TS-5 and TS-3) were treated with four paclobutrazol concentrations (P0 = Control, P1 = 100 mg L−1, P2 = 200 mg L−1, P3 = 300 mg L−1). The experiment was executed in RCBD-factorial design with three replications. Compared with P0, treatment P3 improved the leaf greenness of sesame by 17%, 38%, and 60% at 45, 85, and 125 days after sowing, respectively. However, P3 treatment decreased the leaf area of sesame by 14% and 20% at 45 and 85 days after sowing than P0, respectively. Compared with P0, treatment P3 increased the leaf area by 46% at 125 days after sowing. On average, treatment P3 also improved the total biomass production by 21% and partitioning in roots, stems, leaves, capsules, and seeds by 23%, 19%, 23%, 22%, and 40%, respectively, in the whole growing seasons as compared to P0. Moreover, under P3 treatment, sesame attained the highest seed yield and lowest seed shattering by 27% and 30%, respectively, compared to P0. This study indicated that by applying the paclobutrazol concentration at the rate of 300 mg L−1 in sesame, the leaf greenness, leaf areas, biomass accumulation, partitioning, seed yield, and shatter resistance could be improved. Thus, the optimum paclobutrazol level could enhance the dry matter accumulation and seed production capacity of sesame by decreasing shattering losses under rainfed conditions.


Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 252
Author(s):  
Muhammad Shahinur Alam ◽  
David William Lamb ◽  
Nigel W. M. Warwick

Estimating transpiration as an individual component of canopy evapotranspiration using a theoretical approach is extremely useful as it eliminates the complexity involved in partitioning evapotranspiration. A model to predict transpiration based on radiation intercepted at various levels of canopy leaf area index (LAI) was developed in a controlled environment using a pasture species, tall fescue (Festuca arundinacea var. Demeter). The canopy was assumed to be a composite of two indistinct layers defined as sunlit and shaded; the proportion of which was calculated by utilizing a weighted model (W model). The radiation energy utilized by each layer was calculated from the PAR at the top of the canopy and the fraction of absorbed photosynthetically active radiation (fAPAR) corresponding to the LAI of the sunlit and shaded layers. A relationship between LAI and fAPAR was also established for this specific canopy to aid the calculation of energy interception. Canopy conductance was estimated from scaling up of stomatal conductance measured at the individual leaf level. Other environmental factors that drive transpiration were monitored accordingly for each individual layer. The Penman–Monteith and Jarvis evapotranspiration models were used as the basis to construct a modified transpiration model suitable for controlled environment conditions. Specially, constructed self-watering tubs were used to measure actual transpiration to validate the model output. The model provided good agreement of measured transpiration (actual transpiration = 0.96 × calculated transpiration, R2 = 0.98; p < 0.001) with the predicted values. This was particularly so at lower LAIs. Probable reasons for the discrepancy at higher LAI are explained. Both the predicted and experimental transpiration varied from 0.21 to 0.56 mm h−1 for the range of available LAIs. The physical proportion of the shaded layer exceeded that of the sunlit layer near LAI of 3.0, however, the contribution of the sunlit layer to the total transpiration remains higher throughout the entire growing season.


2009 ◽  
Vol 36 (7) ◽  
pp. 645 ◽  
Author(s):  
Dennis H. Greer ◽  
Sylvie M. Sicard

Assessing the impacts of environmental stresses on plant growth and productivity requires an understanding of the growth processes and the carbon economy that underpins this growth. Potted grapevines of the Vitis vinifera L. cv. Semillon were grown in a controlled environment and canopy growth; leaf, bunch and stem extension and net photosynthesis were routinely measured from budbreak to harvest. Allometric relationships enabled dry matter to be determined and, with net photosynthesis, used to determine the shoot carbon economy. Stems, leaves and bunches all followed a sigmoid growth pattern with leaves and stems allocated similar amounts of biomass and carbon while bunches had twice as much. Rates of carbon sequestered as biomass exceeded rates of carbon acquisition through net photosynthesis for over 25 days after budbreak. Despite the high demand for biomass in bunch growth, rates of carbon sequestration actually declined and overall, the vines maintained a positive carbon balance throughout the period of bunch growth. The Semillon shoots relied on carbon reserves to commence growth then produced a 53% carbon surplus after leaf (9%), stem (10%) and bunch (28%) growth demands were satisfied. This suggests these vines also allocated carbon to reserves to sustain the next season’s growth.


1988 ◽  
Vol 68 (4) ◽  
pp. 935-940 ◽  
Author(s):  
M. TOLLENAAR ◽  
T. W. BRUULSEMA

The response of rate and duration of kernel dry matter accumulation to temperatures in the range 10–25 °C was studied for two maize (Zea mays L.) hybrids grown under controlled-environment conditions. Kernel growth rates during the period of linear kernel growth increased linearly with temperature (b = 0.3 mg kernel−1 d−1 °C−1). Kernel dry weight at physiological maturity varied little among temperature treatments because the increase in kernel growth rate with increase in temperature was associated with a decline in the duration of kernel growth proportional to the increase in kernel growth rate.Key words: Zea mays L, period of linear kernel dry matter accumulation, controlled-environment conditions, kernel growth rate


2012 ◽  
Vol 10 (1) ◽  
pp. 16-22 ◽  
Author(s):  
M. Z. U. Kamal ◽  
M. N. Yousuf

The investigation was carried out to evaluate the effect of different organic manures on turmeric with reference to vegetative growth, biomass production, rhizome yield and its attributes of turmeric (Curcuma longa L.). Turmeric showed better response to the application of organic manures. Plant with neem cake application had the taller plant (79.30 cm), maximum number of tillers per plant (5.40), leaf number (5.40), leaf area (44.09) leaf area index (0.429), fresh weight of halum ( 190.05g), fresh weight of root (49.13 g), fresh weight of rhizome per plant (256.21 g) and dry weight of halum (15.21g), dry weight of root (7.32 g), dry weight of rhizome per plant (40.35 g), total dry matter yield (6.85 t ha-1) than those received other types of manures. Moreover, yield attributes such as number of mother rhizomes per plant-1 (1.75), more number of primary rhizomes per plant-1 (5.19), secondary rhizomes per plant-1 (18.03) and tertiary rhizomes per plant (7.69) were also highly accelerated by neem cake application. Similarly, the same treatment expressed the best in terms of size of mother rhizome (7.69 cm), primary rhizome (21.86 cm) and secondary rhizomes (7.05 cm).All these parameters in cumulative contributed to  produce the highest estimated fresh rhizomes yield & cured rhizomes yield (29.48 t ha-1, 5.59 t ha-1 respectively). The highest curing percentage (20.28) was observed in T3 treatment having mustard cake@ 2.0 t/ha. Thus, organic manure like neem cake was best fitted natural fertilizer for turmeric cultivation.DOI: http://dx.doi.org/10.3329/agric.v10i1.11060The Agriculturists 2012; 10(1): 16-22


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