Shoot

About: Shoot is a research topic. Over the lifetime, 32188 publications have been published within this topic receiving 693348 citations.

Effects of Different Soil Salinity Levels on Germination and Seedling Growth of Safflower (Carthamus tinctorius L.)

Abstract: Safflower (Carthamus tinctorius L.) is rated as moderately salt tolerant and it can produce profitable crops on saline soils. It is slightly more tolerant of salinity than barley but is more tolerant than wheat. Because salinity reduces germination and delays emergence, safflower stands tend to be irregular and crop yield is depressed. However, some varieties are less affected by salinity than others. In this study, we aimed to determine the effects of soil salinity levels (0.8, 2.5, 5.1, 8.7, 13.0, 15.2 and 23.0 dS m-1) on germination and seedling growth of three safflower varieties, one of which is spiny (5-154 cv.) and two of which are spineless (Yenice 5-38 and Dincer 5-118 cv.). Emergence rate, root and shoot length, root and shoot dry weight, root/shoot dry weight ratio, root and shoot dry weight salt stress index were investigated. The results showed that the highest values for the investigated traits were obtained from variety 5-154 (spiny), while they diminished with increasing soil salinity in all cultivars. Among the varieties, the highest emergence rate, root length, shoot length, root dry weight, shoot dry weight and root/shoot dry weight ratio at 23.0 dS m-1 were determined from 5-154 cv. with 23.35%, 3.54 cm, 4.97 cm, 7.23 mg, 26.73 mg and 20.77%, respectively. Moreover, 5-154 cv. gave the higher root and shoot dry weight salt stress index, especially at high salinity levels. The seedling growth of varieties was inhibited by 5.1 dS m-1 although they showed varying responses. At the first development stage, the root growth of safflower was more adversely affected compared to shoot growth by soil salinity. If the cultivation of safflower on saline soils is required, spiny varieties should be preferred.

Nitrogenase Activity Measurements in Intact Plants of Alnus incana

Abstract: A technique for C2H2-reduction assay on intact plants of Alnus incana (L.) Moench was evaluated. Cloned plants were grown, in pots, on fine gravel. During assay only the pot was inserted into a Perspex incubation chamber of simple construction. The incubation volume was rather small, plants with various shoot heights could be used, and the shoot was not exposed to the C2H4 produced. Intact plants showed high and constant C2H2-reduction rates during several hours of incubation. In comparison, excised nodulated roots conventionally incubated in test tubes showed low and decreasing rates, due to removal of the photo-synthesizing shoot and injury to the root nodules when drawn from the pot. Repeated nitrogenase activity assays on the same intact individual plants did not affect growth. The technique thus proved useful in studies. where repeated nitrogenase activity measurements are important.

Expression of the Arabidopsis vacuolar H+-pyrophosphatase gene (AVP1) improves the shoot biomass of transgenic barley and increases grain yield in a saline field

Abstract: Summary Cereal varieties with improved salinity tolerance are needed to achieve profitable grain yields in saline soils. The expression of AVP1, an Arabidopsis gene encoding a vacuolar proton pumping pyrophosphatase (H+-PPase), has been shown to improve the salinity tolerance of transgenic plants in greenhouse conditions. However, the potential for this gene to improve the grain yield of cereal crops in a saline field has yet to be evaluated. Recent advances in high-throughput nondestructive phenotyping technologies also offer an opportunity to quantitatively evaluate the growth of transgenic plants under abiotic stress through time. In this study, the growth of transgenic barley expressing AVP1 was evaluated under saline conditions in a pot experiment using nondestructive plant imaging and in a saline field trial. Greenhouse-grown transgenic barley expressing AVP1 produced a larger shoot biomass compared to null segregants, as determined by an increase in projected shoot area, when grown in soil with 150 mm NaCl. This increase in shoot biomass of transgenic AVP1 barley occurred from an early growth stage and also in nonsaline conditions. In a saline field, the transgenic barley expressing AVP1 also showed an increase in shoot biomass and, importantly, produced a greater grain yield per plant compared to wild-type plants. Interestingly, the expression of AVP1 did not alter barley leaf sodium concentrations in either greenhouse- or field-grown plants. This study validates our greenhouse-based experiments and indicates that transgenic barley expressing AVP1 is a promising option for increasing cereal crop productivity in saline fields.

Superoxide dismutase activity in arbuscular mycorrhizal Lactuca sativa plants subjected to drought stress

Abstract: summary Total superoxide dismutase (SOD; EC 1.15.1.1) activity, SOD specific activity and changes in the SOD isoenzymatic pattern were determined in roots and shoots of plants of Lactuca sativa L. cv. Romana colonized by the arbuscular mycorrhiza (AM) fungi Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe or Glomus deserticola (Trappe, Bloss & Menge), and in non-mycorrhizal phosphorus-fertilized controls. Lettuce plants were grown under well watered or drought conditions and were harvested 5 wk or 8 wk after planting. Previous studies have reported that mechanisms that decrease oxidative stress can play an important role in drought tolerance of plants. However, there is little information on either the role of superoxide dismutase in the symbiosis between AM fungi and plants, or about the response at biochemical level of the mycorrhizal symbiosis to drought stress. In our experimental conditions the protein concentration in shoots decreased in all plants as a result of drought stress (except in plants colonized by Glomus mosseae after 8 wk of growth). In general, shoots of mycorrhizal plants had more protein than did shoots of P-fertilized plants, G. deserticola being the treatment with the highest protein concentration. However, in roots the protein concentrations did not vary as clearly as in shoots. The SOD specific activity of 5-wk-old plants under stress conditions was considerably higher in shoots and roots of mycorrhizal than in those of P-fertilized plants, showing increases which ranged from 99% in G. mosseae-mycorrhizas to 150% in G. deserticola-mycorrhizas. Under well watered conditions shoots showed no significant differences in SOD specific activity between treatments, whereas in roots mycorrhizal colonization increased it by 16–18 %. Drought stress increased SOD activity of shoots of control plants by 17%, and that of shoots of plants colonized by G. mosseae and G. deserticola by 93 % and 128 %, respectively. Similar results were also found for roots, regardless of the plant age. The increased SOD activity in mycorrhizal plants was not related to the nutritional status of the plants. Instead, it could be ascribed to a direct mechanism of AM association in response to drought exposure. However, no changes in the SOD isozyme pattern as a consequence of mycorrhizal association or water treatment were observed.