Shoot

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

Root hair length determines beneficial effect of a Glomus species on shoot growth of some pasture species

Abstract: SUMMARY Differences between plant species in the benefit derived from arbuscular mycorrhizal colonization have often been attributed to differences in physical properties of their roots, especially in root hair development. To test this hypothesis, the growth response to phosphate of five pasture species which differed markedly in the length of their root hairs was measured. Plants in the mycorrhizal treatments were inoculated with a Glomus sp. (isolate WUM 10(1)) while non-mycorrhizal plants received control inoculum. Benefit was described as the relative effectiveness of phosphorus (P) for the mycorrhizal plants compared with non-mycorrhizal plants. The beneficial effect of Glomus sp. was inversely related to root hair length of the host plant but it was not well related to root diameter, root length per plant or root/shoot ratio. It is suggested that root hairs and external hyphae of Glomus sp. act as alternative, similar ways of shortening the distance for the diffusion of phosphate in soils.

Stimulatory effect of phosphate-solubilizing fungal strains (Aspergillus awamori and Penicillium citrinum) on the yield of chickpea (Cicer arietinum L. cv. GPF2)

Abstract: The effect of six phosphate-solubilizing fungi (PSF, two strains of Aspergillus awamori , and four of Penicillium citrinum ) isolated from rhizosphere of various crops, was observed on the growth and seed production of chickpea plants ( Cicer arietinum L. cv. GPF2) in pot experiments. The phosphate (P) solubilizing activity of PSF in liquid varied from 38 to 760 μg ml −1 for tricalcium phosphate (TCP) and 28–248 μg ml −1 for mussoorie rock phosphate (MRP). All PSF isolates were biocompatible and produced growth-promoting hormone, Indole acetic acid (IAA), varying in concentration from 2.5 to 9.8 μg ml −1 . Of the various pot experiments carried out in green house, maximum stimulatory effect on chickpea plants growth was observed by inoculation of two A. awamori strains. This treatment resulted in 7–12% increase in shoot height, nearly three-fold increase in seed number and two-fold increase in seeds weight as compared to the control (un-inoculated) plants. Inoculation of four strains of P. citrinum exhibited lesser stimulatory effect. It showed 7% increase in shoot height, two-fold increase in seed number and 87% increase in seeds weight as compared to the control plants. However, a consortium of all the six fungal isolates showed no stimulatory effect on chickpea plants growth.

Root herbivory reduces growth and survival of the shoot feeding specialist Pieris rapae on Brassica nigra

Abstract: Plants may respond to herbivore attacks by changing their chemical profile. Such induced responses occur both locally and systemically throughout the plant. In this paper we studied how Brassica nigra (L.) Koch (Brassicaceae) plants respond to two different root feeders, the endoparasitic nematode Pratylenchus penetrans Cobb (Tylenchida: Pratylenchidae) and the larvae of the cabbage root fly Delia radicum L. (Diptera: Anthomyiidae). We tested whether the activities of the root feeders affected the survival and development of the shoot feeding crucifer specialist Pieris rapae (L.) (Lepidoptera: Pieridae) via systemically induced changes in the shoots. Overall, P. rapae larvae grew slower and produced fewer pupae on plants that were infested with root feeders, especially on plants infested with P. penetrans. This effect could not be attributed to lower water or protein levels in these plants, as the percentage of water in the controls and root infested shoots was similar, and protein content was even higher in root infested plants. Both glucosinolate as well as phenolic levels were affected by root feeding. Initially, glucosinolate levels were the lowest in root infested plants, but on P. penetrans infested plants they increased more rapidly after P. rapae started feeding than in controls or D. radicum infested plants. Plants with D. radicum feeding on their roots had the highest phenolic levels at all harvest dates. Our results indicate that root feeding can significantly alter the nutritional quality of shoots by changes in secondary metabolite levels and hence the performance of a specialist shoot feeder. [KEYWORDS: above-ground ; below-ground interactions ; black mustard ; Brassicaceae ; cabbage ; cabbage root fly ; Delia radicum ; endoparasitic nematodes ; induced plant responses ; glucosinolates ; phenolics ; Pratylenchus penetrans ; proteins]

Transport of exogenous auxin in two-branched dwarf pea seedlings (Pisum sativum L.) : Some implications for polarity and apical dominance.

Abstract: Dwarf pea plants bearing two cotyledonary shoots were obtained by removing the epicotyl shortly after germination, and the patterns of distribution of (14)C in these plants was investigated following the application of [(14)C]IAA to the apex of one shoot. Basipetal transport to the root system occurred, but in none of the experiments was (14)C ever detected in the unlabelled shoot even after transport periods of up to 48 h. This was true both of plants with two equal growing shoots and of plants in which one shoot had become correlatively inhibited by the other, and in the latter case applied whether the dominant or subordinate shoot was labelled. In contrast, when [(14)C]IAA was applied to a mature foliage leaf of one shoot transfer of (14)C to the other shoot took place, although the amount transported was always low. Transport of (14)C from the apex of a subordinate shoot on plants bearing one growing and one inhibited shoot was severely restricted compared with the transport from the dominant shoot apex, and in some individual plants no transport at all was detected. Removal of the dominant shoot apex rapidly restored the capacity of the subordinate shoot to transport apically-applied [(14)C]IAA, and at the same time led to rapid cambial development and secondary vascular differentiation in the previously inhibited shoot. Applications of 1% unlabelled IAA in lanolin to the decapitated dominant shoot maintained the inhibition of cambial development in the subordinate shoot and its reduced capacity for auxin transport. These results are discussed in relation to the polarity of auxin transport in intact plants and the mechanism of correlative inhibition.