News Update on Growth of Wheat: Dec 2020

A genetic analysis of the spring-winter habit of growth in wheat

Developmental patterns of growth have been studied in nine spring and 10 winter wheat cultivars and in a number of crosses involving both groups. Among the spring cultivars five responded to vernalization while four did not. There was a very wide range in responsiveness to vernalization among the winter cultivars, ranging from the responsive Winter Minflor to Jones Fife which appeared not to respond at all to the ’30-day vernalization test’. The spring habit of growth was governed by three dominant genes, any one of which was able to inhibit the expression of the winter habit. Progress has been made in establishing relationships among several spring cultivars. Those carrying the gene Sk, either alone or in combination with others, appeared to be non-responsive to vernalization. In the absence of Sk all spring cultivars so far tested exhibited a positive response. Winter selections made from spring-winter crosses always resembled the winter parent with respect to the intensity of the winter characteristic. While all winter wheats carry recessive alleles at all three loci, the differences in expression which exist between them appear to have been due to the presence of multiple recessive alleles at these loci. Further evidence of the association of leaf and spikelet numbers with days to ear emergence is presented. [1]

Seed reserve utilization and seedling growth of wheat as affected by drought and salinity

In germination stage, decreased wheat (Triticum aestivum L.) seedling growth (mg per seedling) as affected by drought and salinity stresses is a well-known phenomenon. The heterotrophic seedling growth can be defined as a product of two components: (1) the weight of mobilized seed reserve (WMSR; mg per seed), and (2) the conversion efficiency of utilized seed reserve to seedling tissue (mg seedling dry weight (SLDW) per mg utilized seed reserve). The first component can be further divided into (1) initial seed weight (mg per seed), and (2) the fraction of seed reserve, which is mobilized (mg mobilized seed reserve per mg initial seed weight). The objective of this study was the identification of the sensitive seedling growth component(s) in response to drought and salinity stresses. Two experiments were separately conducted using various osmotic pressures (OP) induced by polyethylene glycol (PEG; 0–1.8 MPa, with interval of 0.2) in experiment 1 and by NaCl (0, 0.4, 0.8, 1.2 and 1.6 MPa) in experiment 2. Two wheat cultivars were used in each experiment. In both experiments, seedling growth, fraction of seed reserve utilization and weight of mobilized seed reserve decreased with increasing drought and salt intensity. However, drought and salinity stresses had no effect on the conversion efficiency. It was concluded that the sensitive component of seedling growth is the weight of mobilized seed reserve. Thus, appropriate efforts such as plant breeding programs should be focused on improvement of seed reserve mobilization in order to obtain increased seedling growth under drought and salinity stresses. [2]

Effects of Drought and High Temperature on Grain Growth in Wheat

The effects of two levels of temperature and of water supply on grain development of wheat (cv. Warigal) were studied by imposing treatments during the early or late period of cell division. High temperature (28°C day/20°C night) accelerated development of the grain. Dry matter accumulation and cell division proceeded at a higher rate but had a shorter duration in the high temperature treatments. Maximum cell number, final cell size and the number of large starch granules per cell were not significantly reduced by high temperature. Drought and drought × high temperature reduced the storage capacity of the grain, with a decrease in number of cells and starch granules in the endosperm. Cell size was also reduced when treatments were imposed late during cell division. Duration of dry matter accumulation and cell division was reduced in the drought and drought × high temperature treatments. The combined effects of drought and high temperature were much more severe than those of each separate treatment. The amount of sucrose per cell was similar in all treatments. It appears unlikely that the supply of sucrose to the endosperm cells is the main limiting factor of dry matter accumulation in both drought and high temperature treatments. [3]

Assessment of Concentrations of Nano and Bulk Iron Oxide Particles on Early Growth of Wheat (Triticum aestivum L.)

Aims: In this work we assessed Fe2O3 nanoparticles with bulk Fe2O3 for possible phytotoxicity and stimulative effects on wheat seed germination and early growth stage.

Methodology: The treatments in the experiment were five concentrations of bulk (100, 500, 1000, 5000 and 10000 ppm) and five concentrations of nanosized Fe2O3 (100, 500, 1000, 5000 and 10000 ppm) and an untreated control. Germination tests were performed according to the rule issued by ISTA. Analysis of variance (ANOVA) was performed between treatment samples. The information was analyzed using MSTAT-C computer software. Means compared by multiple range Duncan test and a 95% significance level (p < 0.05) was employed for all comparisons.

Results: Results showed that exposure of seeds to 100 ppm iron oxide nanoparticles indicated the greatest germination rate (by 41% more than control group) related to other treatments. Increasing nanoparticles concentration above 100 ppm reduced seed germination rate. It has not found any significant effects by bulk and nanoparticles on elongation of shoot, root and seedling of wheat. Application of 100 ppm concentration of nanosized Fe2O3 reduced mean germination time (MGT) by 38.5% in comparison to the control, while 100 ppm concentration of bulk Fe2O3 did not decrease MGT in comparison with the control. The highest root biomass was achieved from concentration of 100 ppm nano- Fe2O3, but an increased concentrations of nanoparticles Fe2O3 significantly reduced root weight. Nevertheless, on the basis of these results it is highly recommended that the influence of low dose nanomaterial be assessed in order to encourage seed germination and seedling growth. [4]

Effect of Gravity Variation on the Growth of Wheat and Guinea Corn Seedlings

In this study, the impact of gravity on plant growths was studied to determine the orientation of the roots and shoots under simulated microgravity using the clinostat. The experiment was performed with two local seeds-wheat (Triticum aestivum) and guinea corn (Sorghum bicolor).

The agar-agar solution prepared was evenly distributed into the petri dishes where nine seeds each of wheat and guinea corn was planted on four petri dishes. The petri dishes containing the seeds were cultivated in the wet chamber for about 20-30 hours. Three petri dishes were selected in the following order, 1g, 90o turned and clinorotated samples respectively. Five readings were taking at thirty minutes interval.

Data on plants growth were collected from photographs taken during the course of the experiments and analyzed using Image J software to measure the root curvature and growth rate.

The results show that the wheat has the longest root of about 4.2 cm at 90 minutes and Guinea corn 2.58 cm at 120 minutes. The growth rate of clinorotated wheat is 1.88 times that of guinea corn at 90 minutes while that of 1g remained the same. The speed of clinorotation did not affect growth of clinorotated wheat and guinea corn but growth rate of guinea corn was about 23% lower than wheat. The higher value of angle indicates a more pronounced curvature of the root therefore; wheat germinates faster than guinea corn in simulated microgravity. [5]

Reference

[1] Pugsley, A.T., 1971. A genetic analysis of the spring-winter habit of growth in wheat. Australian Journal of Agricultural Research, 22(1), pp.21-31.

[2] Soltani, A., Gholipoor, M. and Zeinali, E., 2006. Seed reserve utilization and seedling growth of wheat as affected by drought and salinity. Environmental and Experimental Botany, 55(1-2), pp.195-200.

[3] Nicolas, M.E., Gleadow, R.M. and Dalling, M.J., 1984. Effects of drought and high temperature on grain growth in wheat. Functional Plant Biology, 11(6), pp.553-566.

[4] Feizi, H., Moghaddam, P., Shahtahmassebi, N. and Fotovat, A. (2013) “Assessment of Concentrations of Nano and Bulk Iron Oxide Particles on Early Growth of Wheat (Triticum aestivum L.)”, Annual Research & Review in Biology, 3(4), pp. 752-761. Available at: https://journalarrb.com/index.php/ARRB/article/view/24882 (Accessed: 15December2020).

[5] Aluko, O. E. and Onabowale, M. K. (2019) “Effect of Gravity Variation on the Growth of Wheat and Guinea Corn Seedlings”, Journal of Experimental Agriculture International, 29(3), pp. 1-9. doi: 10.9734/JEAI/2019/31325.

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