Seedcoat adherence to emerged cotyledons of seedless watermelons (Citrullus lanatus (Thunb.) Matsum & Naki) results in distortion of seedlings that effectively restricts the number of productive plants in a planting. Significantly fewer seedcoats adhered to cotyledons when seeds were oriented with the radicle end up at a 45° or 90° angle than when seeds were oriented horizontally or with the radicle end down at a 45° or 90° angle. Emergence was not affected by seed orientation.
The effects of seed priming and seed orientation on seedcoat adherence and seedling development of containerized muskmelon transplants were investigated. Seeds of muskmelon `Top Net SR' were primed for 6 days in darkness at 25 °C in an aerated solution of KNO3 (0.35 M). Primed and nonprimed seeds were individually planted in Styrofoam trays in the greenhouse. Seeds were carefully oriented with the radicle down, up, or in the horizontal position, and covered with 0.5 cm of the growing mix. Seed priming and seed orientation affected both seedcoat adherence and seedling development, and interaction between priming and orientation was significant for seedcoat adherence. Our data indicate that seed priming can minimize seedcoat adherence during emergence of muskmelon seeds.
The effects of seed priming and seed orientation on seedcoat adherence and seedling development of containerized muskmelon transplants were investigated. Seeds of muskmelon `Top Net SR' were primed for 6 days in darkness at 25 °C in an aerated solution of KNO3 (0.35 m). Primed and nonprimed seeds were individually planted in Styrofoam trays in the greenhouse. Seeds were carefully oriented with the radicle down, up, or in the horizontal position, and covered with 0.5 cm of the growing mix. Seed priming and seed orientation affected both seedcoat adherence and seedling development, and interaction between priming and orientation was significant for seedcoat adherence. Our data indicate that seed priming can minimize seedcoat adherence during emergence of muskmelon seeds.
germination and seedling emergence. Therefore, temperature may be an important influence factor for germination of litchi seeds. Seed orientation and sowing depth both play important roles in seed germination and seedling emergence ( Aou-ouad et al., 2014
ADHase enables plants to adapt to hypoxic stress. Figure 9 shows that H 2 O 2 , aeroponics, and orientation of the embryo in the corn seed strongly affected the activity of the ADHase. When corn seeds had lain with the embryos beneath and pressed
‘TAMBel-2’ bell pepper transplants (Capsicum annuum L.) were grown in a greenhouse for 39 days in north–south (N–S) oriented trays. About 69% of the plants had monodirectional (one plane pointing either N–S, E–W, NW–SE, or SW–NE) lateral root patterns, 23% had bidirectional (two planes), and 7% had omnidirectional (all around) root patterns relative to a N–S greenhouse tray orientation. Transplants were planted with cotyledons N–S (parallel to the N–S bed), with cotyledons E–W (perpendicular to the N–S bed), and at random, without regard to orientation. These plants subsequently were cultivated either deeply (9 cm) or shallowly (3 cm) 3, 5, and 7 weeks after transplanting. Transplants planted E–W by cotyledon orientation yielded significantly more early and overall marketable pods in contrast to those planted N–S by cotyledon orientation or at random. Deep cultivation decreased productivity in contrast to shallow cultivation and negated any benefit to E–W cotyledon orientation. Root and cotyledon orientations in field-seeded peppers were determined for ‘Hidalgo’, ‘TAM-Mild Chile-2’, ‘TAMBel-2’, and ‘Grand Rio 66’ peppers ≈2 months after field-seeding. At least 95% of the populations in all cultivars had monodirectional root orientations. Generally, orientations were divided equally among N–S, E–W, NW–SE, and NE–SW directions. Cotyledon orientation highly correlated with root orientation in all cultivars.
Lycopersicon esculentum cv. UC82b cotyledons were co-cultivated with A. tumefaciens carrying vectors with modified isopentenyl transferase (ipt) genes. The ipt gene was placed under the control of the RUBISCO promoter in both the sense and antisense orientation. Over 50 transformants were recovered on kanamycin-containing media. Seeds from RO plants were germinated on selective media and R1 plants transformed with the ipt gene identified by PCR and Southern blot hybridization. Phenotypes of the R1 plants, whether transformed with the ipt gene in the sense or antisense orientation, were comparable to the control plants transformed with an inactive cytokinin gene. Fruit weights from both were similar to those from control plants, however, yields were reduced and ripening delayed. Most fruit had no seeds or very few small seeds. Cytokinin levels are being determined in order to correlate them to the observed phenotypes.
The effects of a magnetic field on biological systems have been studied extensively in recent years. Murphy (1) reported that a magnetic field accelerates seed germination. Boe and Salunkhe (2) suggested that the magnetic field might act upon auxin or enzyme reactions, or influence free radical formation in inducing tomato fruit ripening. Mericle et al. (3) reported that the magnetic field did not affect the rate of germination of barley seeds, but did increase the rate of shoot and root growth. According to Pittman (4), both germination and growth rates of wheat, oat, and barley seeds were enhanced by a magnetic field at certain orientation.
Nuclear Magnetic Resonance Imaging is currently being investigated as a nondestructively and noninvasively observing plant-water relationships, Researchers have not considered the effects of magnetic fields on plant growth and development. This study was conducted to investigate the effects of magnetic fields on seed water imbibition and radicle growth. Corn (cv. pioneer 3379), pea (cv. little marvel), and soybean (cvs. forrest and D86-4669) seeds were embedded in petri dishes with water saturated Smither's oasis porus foam, and were oriented for the East, South, West, and North. Seeds were exposed to either 1.5 Tesla or 1×10-10 Tesla static magnetic field for 48 hours. Changes in seed weights and radicle lengths were measured. Results showed that the strong magnetic field and seed orientations had no effect on the water imbibition rate. However, growth of corn and pea radicles was affected by the magnetic field. The 1.5 Tesla magnetic field enhanced the growth of corn radicle length, whereas it retarded the growth of pea radicles.
Magnetic Resonance Imaging (MRI) is currently considered as a nondestructive and noninvasive method for observing the distribution, concentration, and status of water in biological materials. However, effects of static magnetic fields of MRI systems on plant growth and development remain controversial. This study was conducted to investigate the water imbibition and radicle growth of Pisum sativum (cv. Little Marvel), Zea mays (cv. Pioneer 3379), and Glycine max (cv. Forrest) seeds oriented to four directions and exposed to six different magnetic field strengths commonly used in MRI systems.
Seeds were embedded in a water saturated synthetic foam medium, and were oriented, with respect to their hilum or embryo, to the east, south, west, or north. Seeds were then exposed to either 2, 4, 6, 8, 10, or 15 kilogauss static magnetic fields for 48 hours (water imbibition) or 54 hours (radicle growth).
The orientation of seeds and the magnetic field strengths had no effect on water imbibition or radicle growth of seeds tested. However, long term exposure retarded pea radicle growth in 2 KG treatment, enhanced soybean radicle growth in 10 KG treatment, but had no effect on corn radicle growth.