Seed morphology and ultrastructure in Citrus garrawayi (Rutaceae) in relation to germinability

2007 ◽  
Vol 55 (6) ◽  
pp. 618 ◽  
Author(s):  
Kim N. Hamilton ◽  
Sarah E. Ashmore ◽  
Rod A. Drew ◽  
Hugh W. Pritchard

Combinational traits of seed size and seed-coat hardness in Citrus garrawayi (F.M.Bailey) (syn. of Microcitrus garrowayi) were investigated as markers for estimation of seed morphological and physiological maturity. Seed size (length) and coat hardness correlated well with changes in seed coat and embryo morphological development, dry-weight accumulation, decreases in moisture content and a significant increase in germinability. Seed moisture content decreased from 82 ± 1% in immature seeds to 40 ± 1% at seed maturation. The outer integument of immature seeds consisted of thin-walled epidermal fibres from which outgrowths of emerging protrusions were observed. In comparison, mature seed coats were characterised by the thickening of the cell walls of the epidermal fibres from which arose numerous protrusions covered by an extensive mucilage layer. Immature seeds, with incomplete embryo and seed-coat histodiffereniation, had a low mean germination percentage of 4 ± 4%. Premature seeds, with a differentiated embryonic axis, were capable of much higher levels of germination (51 ± 10%) before the attainment of mass maturity. Mature seeds, with the most well differentiated embryonic axis and maximum mean dry weight, had the significantly highest level of germination (88 ± 3%).

2007 ◽  
Vol 47 (6) ◽  
pp. 683 ◽  
Author(s):  
Pippa J. Michael ◽  
Kathryn J. Steadman ◽  
Julie A. Plummer

Seed development was examined in Malva parviflora. The first flower opened 51 days after germination; flowers were tagged on the day that they opened and monitored for 33 days. Seeds were collected at 12 stages during this period and used to determine moisture content, germination of fresh seeds and desiccation tolerance (seeds dried to 10% moisture content followed by germination testing). Seed moisture content decreased as seeds developed, whereas fresh (max. 296 mg) and dry weight (max. 212 mg) increased to peak at 12–15 and ~21 days after flowering (DAF), respectively. Therefore, physiological maturity occurred at 21 DAF, when seed moisture content was 16–21%. Seeds were capable of germinating early in development, reaching a maximum of 63% at 9 DAF, but germination declined as development continued, presumably due to the imposition of physiological dormancy. Physical dormancy developed at or after physiological maturity, once seed moisture content declined below 20%. Seeds were able to tolerate desiccation from 18 DAF; desiccation hastened development of physical dormancy and improved germination. These results provide important information regarding M. parviflora seed development, which will ultimately improve weed control techniques aimed at preventing seed set and further additions to the seed bank.


1992 ◽  
Vol 2 (2) ◽  
pp. 89-95 ◽  
Author(s):  
D. Gray ◽  
J. R. A. Steckel ◽  
L. J. Hands

AbstractThe effects of development of leek seeds at 20/10°, 25/15° and 30/20°C (day/night) and drying of seed harvested at different developmental stages on subsequent performance were examined in each of 3 years. An increase in temperature from 20/10° to 30/20°C reduced mean seed weight from 2.90 to 2.55 mg as a result of a reduction in the duration of seed growth from 80 to 55 days; seed growth rate was unaffected. Seed moisture content reached a minimum, up to 35 days after the attainment of maximum seed dry weight and 115, 90 and 70 days after anthesis at 20/10°, 25/15° and 30/20°C, respectively. The curves relating seed moisture to time for each temperature regime were mapped onto a single line accounting for >90% of the variation in moisture content, using accumulated day-degrees >6°C instead of chronological time. Seeds were capable of germinating when seed moisture contents were >60% (fresh weight basis), but maximum viability and minimum mean time to germination were not attained until seed moisture contents at harvest had fallen to 20–30%. Germination was little affected by temperature of seed development. Drying immature seeds increased percentage germination. Growing seeds at 30/20°C and drying at 35°C and 30% RH raised the upper temperature limit of germination compared with growing at 20/10°C and drying at 15°C and 30% RH.


1987 ◽  
Vol 65 (11) ◽  
pp. 2420-2424 ◽  
Author(s):  
Daniel M. Baker ◽  
Harry C. Minor ◽  
Billy G. Cumbie

Seeds of soybean (Glycine max (L.) Merr.) were harvested from greenhouse-grown plants and fractures of the seed coat were examined with a scanning electron microscope. The seed coat was well differentiated from the outer integument when the seed had reached approximately 30% maximum seed size. At this time, the osteosclereids began to separate, becoming fully detached along their radial walls by 50% maximum seed size. Macrosclereid secondary wall development occurred during growth of the seed from 50 to 100% maximum seed size. Near R6 (100% maximum seed size) the endothelium began differentiation from the integumentary tapetum (inner integument) and was fully differentiated by physiological maturity (R7). From R7 to harvest maturity (R8) the seed lost moisture content and decreased in size. The parenchyma of the seed coat collapsed in response to this dehydration.


2014 ◽  
Vol 62 (4) ◽  
pp. 305 ◽  
Author(s):  
Qin-ying Lan ◽  
Ke Xia ◽  
Xiao-feng Wang ◽  
Jun-wei Liu ◽  
Jin Zhao ◽  
...  

The Xishuangbanna tropical rainforest in Yunnan Province is the greatest biodiversity hotspot in China. However, the biodiversity of this region is under threat, making seed conservation through seed and/or germplasm banking particularly urgent and crucial. Seed desiccation sensitivity limits the possibility of seed banking of 47% of tropical rainforest species. Thus, knowing if a species has desiccation-sensitive seeds is an important first step in seed banking; however, often resources are limited, making it difficult to determine storage behaviour for all the species in a region. Prediction of seed sensitivity using the SCR–SM model based on seed-coat ratio (SCR) and seed dry mass (SM) might be an alternative for determining desiccation sensitivity of seeds of each species. Here, seed-desiccation sensitivity of 101 woody species from the Xishuangbanna tropical forest were analysed using this model, and physiological determinations were made for a total of 25 species. Seed storage behaviour for 59 species was used for model validation, and storage behaviour of 88% of these species was successfully predicted. Seed storage behaviour of 83% of the 59 species was successfully predicted using the 1000-seed weigth–moisture content (TSW–MC) criteria, which include seeds with 1000-seed weight >500 g and seed moisture content at shedding of 30 –70%. The two predictive methods were subsequently used to predict seed desiccation sensitivity for another 42 species from Xishuangbanna whose storage behaviour was uncertain. Our results indicated that ~50% of the species in Xishuangbanna are likely to have desiccation-sensitive seeds.


2006 ◽  
Vol 20 (4) ◽  
pp. 862-866 ◽  
Author(s):  
Peter H. Sikkema ◽  
Darren E. Robinson ◽  
Christy Shropshire ◽  
Nader Soltani

Weed management is a major production issue facing otebo bean growers in Ontario. Field trials were conducted at six Ontario locations during a 2-yr period (2003 and 2004) to evaluate the tolerance of otebo bean to the preplant incorporated (PPI) application of EPTC at 4,400 and 8,800 g ai/ha, trifluralin at 1,155 and 2,310 g ai/ha, dimethenamid at 1,250 and 2,500 g ai/ha,S-metolachlor at 1,600 and 3,200 g ai/ha, and imazethapyr at 75 and 150 g ai/ha. EPTC, trifluralin, dimethenamid, andS-metolachlor applied PPI resulted in minimal (less than 5%) visual injury and with exception of the low rate of dimethenamid causing a 16% reduction in shoot dry weight and the high rate causing an 8% plant height reduction had no adverse effect on plant height, shoot dry weight, seed moisture content, and yield. Imazethapyr applied PPI caused up to 7% visual injury and reduced plant height, shoot dry weight, and yield 8, 18, and 12% at 75 g/ha and 19, 38, and 27% at 150 g/ ha, respectively. Seed moisture content was also reduced by 0.4% with both rates. Based on these results, otebo bean is not tolerant of imazethapyr applied PPI at rates as low as 75 g/ha, the proposed use rate. EPTC, trifluralin, dimethenamid, andS-metolachlor applied PPI have a 2× rate crop safety margin for use in otebo bean weed management.


2018 ◽  
Vol 22 (03) ◽  
pp. 69-71
Author(s):  
Binderya G ◽  
Tumenjargal D

The paper presents the results of the study on seed morphology and anatomy of Allium anisopodium Ldb. The seed shape is elliptic, glossy-black in color. The seed surface is scaly and its hilum appears in white color. The seed size is 1.7-2.1 mm long, 1.2-1.4 wide, 0.5-2.1 mm in thick and one thousand seed weight is 1.9 g. The anatomical structure is endospermic one cotyledons seed type. The seed coat thin and cotyledon is emphasized apparently from longitudinal section. The embryo is curved, coiled and black colored embryonic roots are relatively thick. The endosperm is surrounded by seed coat moreover between the cotyledon and embryo.


2003 ◽  
Vol 13 (4) ◽  
pp. 323-327 ◽  
Author(s):  
T. Mai-Hong ◽  
T.D. Hong ◽  
N.T. Hien ◽  
R.H. Ellis

In the hot and dry conditions in which seeds of the tree legume Peltophorum pterocarpum develop and mature in Vietnam, seed moisture content declined rapidly on the mother plant from 87% at 42 d after flowering (DAF) to 15% at 70 DAF. Dry weight of the pods attained a maximum value at about 42 DAF, but seed mass maturity (i.e. the end of the seed-filling phase) occurred at about 62 DAF, at which time seed moisture content was about 45–48%. The onset of the ability of freshly collected seeds to germinate (in 63-d tests at 28–34°C) occurred at 42 DAF, i.e. about 20 d before mass maturity. Full germination (98%) was attained at 70 DAF, i.e. at about 8 d after mass maturity. Thereafter, germination of fresh seeds declined, due to the imposition of a hard seed coat. Tolerance of desiccation to 10% moisture content was first detected at 56 DAF and was complete within the seed population by 84 DAF, i.e. about 22 d after mass maturity. Hardseededness began to be induced when seeds were dried to about 15% moisture content and below, with a negative logarithmic relation between hardseededness and moisture content below this value.


2004 ◽  
Vol 18 (4) ◽  
pp. 893-901 ◽  
Author(s):  
Peter H. Sikkema ◽  
Nader Soltani ◽  
Christy Shropshire ◽  
Todd Cowan

Weed control in white beans is currently limited by the small number of registered herbicides. The tolerance of two white bean cultivars, ‘AC Compass’ and ‘OAC Thunder’, to various postemergence (POST) herbicides at the maximum use rate and twice the maximum use rate for soybean or corn was evaluated at two Ontario locations in 2001 and 2002. Generally, the two cultivars did not differ in their response to the POST herbicides. POST applications of imazamox plus fomesafen, imazamox plus bentazon, and cloransulam-methyl decreased plant height, shoot dry weight, and yield by as much as 29, 41, and 55%, respectively, and increased seed moisture content up to 3.9%. POST applications of thifensulfuron, chlorimuron, and bromoxynil decreased plant height as much as 57%, shoot dry weight by up to 71%, yield as much as 93% and increased seed moisture content up to 15.5%. Based on these results, AC Compass and OAC Thunder white beans do not possess sufficient tolerance to support the registration of imazamox plus bentazon, imazamox plus fomesafen, cloransulam-methyl, thifensulfuron, chlorimuron, and bromoxynil.


Author(s):  
Offurum Julius Chigozie ◽  
C.M. Morgan

The water content determination of two maize species (Yellow corn- and White corn- ) located at Ohaji in Imo State of Nigeria were  considered in this study. This was motivated by the regular reported cases of the seed post-harvest spoilages, especially in the local communities. And the moisture content of a particular seed could vary according to the various location of crop, presumably due to the soil texture. The moisture content of a given crop seed can influence its storage value, as well as its choice of selection during manufacturing processes. It was, thus, necessary to determine the moisture content of the two maize species (white and yellow corn) from Ohaji in Imo State of Nigeria, in order to identify their dispositions, especially during storage. Modified High Constant Temperature Oven method, as prescribed by the International Seed Testing Association (which involves preliminary pre-drying and grinding), was employed, at a temperature of 102oC. This involved the use of dry-weight technique, which is expressed as a percentage of the dry weight of the seeds. The procedure for each sampling was replicated accordingly, and the mean value identified as the actual result. The moisture content for Sample A (white corn) was found to be 31.7%, while that of Sample B (yellow corn) was found to be 21.5%, which shows that the yellow corn would always have longer storage value than the white corn. As any change in the seed moisture content has a way of affecting its storage life, it is advisable not to store the white corn longer than it could be applied in the yellow corn for a better storage value.Keywords: Determination, Moisture Content, White Corn, Yellow Corn, Dry-weight Basis


2019 ◽  
Vol 33 (3) ◽  
pp. 303-316
Author(s):  
Prihatin Ponco Pamungkas ◽  
Maizar Maizar ◽  
Sulhaswardi Sulhaswardi

The study aimed to determine the effect of giving NPK Grower fertilizer and defoliation to seed development and corn crop production. The design used in this study was a Factorial Completely Randomized Design consisting of two factors. The first factor is NPK Grower (N) fertilizer with a dose of 0, 7.5, 15, 22.5g / plant while the second factor is Defoliation (D) with some 0, 2, 4, all leaves under the cob. The parameters observed were changes in seed dry weight (g), changes in seed moisture content (%), speed of accumulation of dry matter (mg / seeds / day), effective filling time (days), harvest age (days), and dry shelled weight ( g). The last observation data were analyzed statistically and continued with a BNJ follow-up test at the level of 5%. The results showed that interactively giving NPK Grower and Defoliation fertilizer had a significant effect on changes in seed dry weight, changes in seed moisture content, speed of dry matter accumulation, harvest age and dry shell weight. The best treatment is in the combination of 22.5g / plant NPK Grower fertilizer treatment and Defoliation of all leaves under the cob (N3D3). The main effect of NPK Grower fertilizer has a significant effect on all parameters. The best treatment for NPK Grower fertilizer is 22.5g / plant (N3). The main effect of Defoliation has a significant effect on all parameters. Best treatment Defoliate all leaves under the cob (D3).


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