THE EFFECTS OF LIGHT AND TEMPERATURE ON THE GROWTH OF AND BALANCES OF CARBON, NITROGEN AND POTASSIUM BETWEEN VICIA FABA L. AND APHIS FABAE SCOP.

Abstract

SUMMARYThe effects of light, temperature and infestation by Aphis fabae Scop, on Vicia faba L. were examined in a factorial experiment. Light was 1116 or 40 //mol m"^ s~^ PPFD and temperature 15/10 °C or 25/20 °C (16 h day/8 h night). Plants and aphids were harvested after 9 d at 25/ 20 °C and 13 dat 15/10 °C. High hght and high temperature increased the relative growth rate (RGR) of aphid colonies, but without interaction. Under high light, alatae produced more nymphs which grew larger. High temperature did not affect nymph production, but mature apterae weighed less. More honeydew was produced at high light. High temperature increased honeydew at high light, but decreased it at low. Reduction in dry weight (d.w.) of infested plants was similar to the calculated dry matter (d.m.) ingested by the aphids except at high light/low temperature, where it was much less. Calculated NAR was increased by high light, but reduced by high temperature. In infested plants, 'true' NAR (calculated from plant d.w. + ingested d.m.) was compared with 'apparent' NAR (calculated from plant d.w. alone). Infestation decreased 'apparent' NAR, but the effect was small at high light/low temperature because 'true' NAR increased. Infested plants at low light/high temperature had negative 'apparent' NARs. High light and high temperature generally decreased leaf diffusive resistance, except that uninfested plants at high light/low temperature had large values. Stem, leaf and root d.w. were all increased by high light and decreased by infestation. Leaf carbohydrate showed similar responses. Chlorophylls were reduced at high light, particularly at low temperature in uninfested plants. These plants showed positive relationships between chlorophyll and (1) the starch: sucrose ratio and (2) leaf total nitrogen, but a negative relationship with leaf diffusive resistance. Leaf potassium (K) and amino nitrogen showed only small responses to light and temperature. Aphids retained > 80 % of N ingested and < 20 % of K. Ingested material contained more K than N, but the ratio of both to carbohydrate was much greater under low light, particularly at high temperature. Aphids under these conditions appeared starved of carbohydrate. Low light increased the proportions of proline, amides and ammonia in both leaf extracts and aphid honeydew.

Physiological and Molecular Mechanism Involved in Cold Stress Tolerance in Plants

“…Meanwhile, LT reduces the utilization of light [82]. Light has a pivotal effect on the relationship between insects and plants, while temperature affects light performance [88]. However, the light also acts as an external signal that influences the growth of the plant [89].…”

THE EFFECT OF LIGHT ON THE RELATIONSHIP BETWEEN APHIS FABAE SCOP. AND ITS HOST PLANT, VICIA FABA L.

“…Figure 3 shows the P/C ratios of the aphids in the present experiment calculated using the calorific values given by Llewellyn & Qureshi (1978). They are plotted against log PPFD, together with some values from Garsed, Davey & Galley (1987) and the mean value obtained by Llewellyn & Qureshi (1978) for A. fabae feeding on V.faba at 9 W m~^ (approximately 38 0 10 100 1000 Photosynthetic photon flux density ixmo\ m~^ s~' (log scale) Fig. 3.…”

“…•, Data from the present work; A, data from Garsed et al (1987); •, the mean value of Llewellyn & Qureshi (1978). y = 0-845-O-223x; r = 0-98; P< 0-001. m~^ s~^PPFD).…”

Effects of cold stress on reproductive biology and epigenetic profiles of the alpine plant Ranunculus kuepferi (Ranunculaceae)

“…Wani et al, 2013;Wani et al, 2016;, such as changes in light utilization, ROS production, carbon assimilation, photosynthesis rate, membrane permeability, fluidity and cell wall architecture, being induced (e.g. Garsed et al, 1987;Sanghera et al, 2011;Longo et al, 2017;Megha et al, 2018). Furthermore, DNA methylation is exhibited to mediate phenotypic plasticity within a single generation and between generations (Boyko et al, 2010).…”

“…Cold temperature stress is defined as chilling (0-20 o C) or freezing (< 0 o C) and represents a major abiotic stress, threatening growth and development e.g., (Chinnusamy et al, 2007;. Most notably, it induces biochemical, physiological, structural and morphological modifications e.g., Wani et al, 2013;Wani et al, 2016; such as changes in light utilization, ROS production, carbon assimilation, photosynthesis rate, membrane permeability, fluidity and cell wall architecture e.g., (Garsed et al, 1987;Chinnusamy et al, 2007;Sanghera et al, 2011;Longo et al, 2017;Kazemi-Shahandashti & Maali-Amiri, 2018;Megha et al, 2018).…”