Dear Fugui,

I don't think ABA must elevate plant net photosynthesis. The effect of ABA on net photosynthesis in plant maybe vary with plant species, ABA concentration and other environmental factors.

Best regards!

Yang

i think ABA may have indirect effect on net chlorophyll content and not on net photosynthesis

 Thanks Yang!

My results confirmed you oppinion.

However, how i interpret this case? do you have any literature about ABA adverse influences on different species net photosynthesis?

Hi, Muneeb. 

Proper contant ABA induce stomotal closure and indirect make net photosynthsis as documents showed. However, my results indicated the increase in poplar with ABA spraying onto leaf. I don;t know how to explain this. 

I'm so sorry that I have no literature in my hand. Recently, my attentions have been given to litter decomposition.

Best regards!

Yang

I agree with Yang , maybe you may consider the concentration and conditions of the experiment.

I don't have references.

Can you give more information about the experimental conditions

Regards

Margarita

Dear Margarita, 

the conditions of my experiment is as follows:

Cuttings of P. cathayana  were selected from from their natural habitat (Ledu, 36°31′ N, 102°28′ E, 3160 m Alt.) in the Qinghai Province, China. Fourty-eight healthy and uniform cuttings germinated from two-year-old rootstocks were selected and grown in a naturally lit, well-ventilated greenhouse (average temperature and relative humidity being 25 °C and 70%, respectively) for four weeks. Each cutting grew in a 10-l plastic pot filled with 8 kg homogenized soil and 8 g slow release fertilizer (13% N, 10% P and 14% K). When cuttings reached about 50 cm in height, they were treated with ABA. In the ABA experiment, leaves of cuttings were sprayed with ABA daily with 10 ml of 50 μM ABA in 0.5% (v/v) Tween 20. The treatments lasted for four weeks. 

Gas exchange was measured at the end of ABA, from 08:00 to 11:30 h with the Li-6400 portable photosynthesis measuring system (Li-Cor Inc., Lincoln, NE) on the fourth or fifth fully expanded leaf. The measurement conditions were as follows: leaf temperature 27 °C, leaf-air vapour pressure deficit 1.5 ± 0.5 kPa, photosynthetic photon flux 1500 μmol m-2 s-1, relative air humidity 70% and ambient CO2 concentration 390 ± 8 μmol mol-1. 

Did ABA induce the net photosynthesis increase under this condition?

Thanks!

Fu, ABA can have both indirect and direct effects on photosynthesis. Indirectly, ABA induced stomatal closure restricts gas entry whereby reduced CO2 availability in the chloroplast limit the photosynthesis. Directly, ABA can also interact and bind to Rubisco and act as a negative regulator of Rubisco activity thereby decrease photosynthesis. However, the relative contributions of these two mechanisms are not clearly tested in a common experimental conditions.

In your case, you sprayed ABA for 4 weeks, I would definitely assume that Pn would be reduced. So, explain your results in terms of these two possible mechanism in case you have data sets collected on RWC, Gs, Pn, Rubisco activity etc. I have attached two papers for your reference. Hope this helps. Good luck

Kind hearted Ravi, thanks for you result and papers! It is helped me very much! I browsed your publications listed in ResearchGate and found there are some coincidence between our research area! Expecting for future communication and cooperation with you and your team!

I think you compared these value with your control groups (water only). How much differed with water-spray?

 Buhara Yucesan, In the ABA experiment, leaves of cuttings were sprayed with ABA daily with 10 ml of 50 μM ABA in 0.5% (v/v) Tween 20 while in control, there was no ABA in sprayed liqued.