Question

Exercise 1. Assuming no further physiological changes occur, calculate the daily (24 hour) carbon balance for leaves of the HL- and LL-grown plants under the following experimental conditions: 1A. Bright light treatment. Plants are kept at a light-level of 200 umol/m2/s for 2 hours, then switched to a light-level of 150°umol/ma/s for 10 hours, then switched back to a light-level of 200 μmol/㎡/s for 2 hours, and finally, left in darkness (0 μmol/m2/s) for 10 hours. This light regime simulates the light conditions in a sunny habitat like a tropical savanna or a semi-arid shrubland. 1B. Dim light treatment. Plants are kept at a light-level of so umol/m2/s for 2 hours, then switched to a light level of 200 μ mol/m2/s for 10 hours, then switched back to a light level of 50 um 1/m2/s for 2 hours, and finally, left in darkness (0 umol/m2/s) for 10 hours. This light regime simulates the light conditions on the floor of a tropical or temperate forest (in the summer). Results for exercise 1 (effect of biochemical acclimation): Daily CO2 balance of HL grown leaves in bright light treatment;mol COlm2 Daily CO2 balance of LL grown leaves in bright light treatmentmol co/m2 Daily CO2 balance of HL grown leaves in dim light treatmentmol CO/m mol CO2/m2 -- -- Daily CO2 balance of LL grown leaves in dim light treatment; Modeling the effects of blochemical and anatomical acclimation to high-light vs low-light conditions on leaf and plant daily carbon balance. (Modifiled from "Analyzing data S.1" in Bowman et al 4E, pg 116). Many plants modify their leaf biochemistry and leaf anatomy depending upon the light conditions they grow under. These acclimation responses presumably optimize the leaves for improved carbon gain under the respective light environments. The figure below from Chapter 5 of your textbook (after Bjorkman 1981) shows the net photosynthetic rates across a range of light conditions for the same species of plant experimentally grown under high-light (HL grown; 920 umol/m2/s photosynthetically active radiation) and low-light (LL grown; 92 μmol/m2/s). In the following exercise you will use these curves to model the effects of acclimation on daily (24 hour) carbon balance for both HL-and LL-grown plants. You will calculate the 24h carbon balance for both kinds of plants placed under contrasting experimental light treatment designed to simulate a 'real world' bright-light habitat and low-light habitat. balance 40 30 Grown in high-light conditions Grown in low-light conditions 500 1,000 1,500 2,000 2,500 Photosynthetically active irradiance (umol/m2/s)

Answer 1

GIVEN THAT:-

Question 1:-

Assuming , no further physiological charges occur ,so .calculate the daily (24 hour) carbon balance for leaves of the HL- LL-grown plants under the following experiment conditions..

1(A)

Theacclimatization of plants at low light conditions result in low level of photosynthetic activity thereby "net photosynthetic CO2 assimilation (mmol/m^2/s)" is lower & no further physiological changes occur as part of acclimatization.

The net primary productivity (NPP) & gross primary productivity (GPP) is maintained normal in this low -light irradiance at night times specifically.

1(B):

This acclimatization is mainly due to "presence of adaptations that support stomata closure & opening" on night times (respiration & photosynthesis rate varies). However, at higher light -irradiance, photosynthetic activity has increased progressively with higher rate of CO2 assimilation by the leaves for daily carbon balance.

As the NPP changes predominantly with nutrient availability and also climate, aquatic producers produces their NPP based on their respiration level and carbon intake level. Open tropical ocean possess soil composition associated with low nutrient level and followed by anchorage that limits growth thereby productivity through photosynthesis low.

In case of desert areas stomata closure and opening affects NPP level as it is low, the reason is hot temperature in deserts followed by increase in transpiration leading to decreased rate of photosynthesis.

Above ,..theory is shown below graph..

tor ig 30 2어- 20 500 1000 4500--20co 2500 -