EFFECT OF SOIL DRYING ON RATE OF STRESS DEVELOPMENT, LEAF GAS EXCHANGE AND PROLINE ACCUMULATION IN ROBUSTA COFFEE (COFFEA CANEPHORAPIERRE EX FROEHNER) CLONES

Abstract

SUMMARYSeasonal drought stresses as a result of changes in global climate and local weather conditions are among the major factors adversely affecting growth and productivity of Robusta coffee (Coffea canephora pierre ex froehner) in many areas producing the crop. It is believed that there exists a wide range of genetic variability among Robusta coffee clones for traits associated with drought tolerance. Therefore, in an attempt to determine differences among Robusta coffee clones for some growth, physiological and biochemical parameters and identify drought-tolerant materials, 12 months old seedlings of six clones (IC-2, IC-3, IC-4, IC-6, IC-8 and R-4) were subjected to two treatments: well-watered control and drought-stressed (soil drying) by withholding irrigation for three weeks in a rain shelter at University Putra Malaysia, Malaysia. The rate of stress development, expressed as extent of wilting and damage to leaves, was considerably higher for clones IC-8, IC-4, R-4 and IC-2 than for IC-3 and IC-6 during the stress period. Leaf water potential (LWP), stomatal conductance (g s ) and rate of net photosynthesis (P N ) progressively decreased but leaf proline (LP) concentration substantially increased with time of exposure of the plants to soil drying. There was a considerable difference between coffee clones for the rate of change in these parameters. All the clones except IC-6 and IC-8 showed a negative carbon balance with the most negative value for R-4 at the end of the stress period. Six days after rewatering, LWP, g s and P N increased rapidly while LP concentration decreased and reached a level equivalent to those of well-watered plants, especially for clones IC-3 and IC-6. Among the drought-stressed plants, IC-6 and IC-3 had still significantly higher shoot growth, total dry matter yield and root to shoot ratio than did IC-2, IC-4, IC-8 and R-4. In general, clones IC-6 and IC-3 exhibited quite a better performance in almost all the parameters considered in this study and seemed to be less sensitive to drought stress. Hence, drought tolerance attributes in these clones could be linked to a more effective osmotic adjustment due to more rapid accumulation of LP and probably some morphological parameters, such as increased root-to-shoot ratio. However, further analyses at molecular level, detail biochemical studies and observations under diverse field conditions are required to come up with more conclusive recommendations.

Comparison of Grafting Techniques and their Effects on some Growth Parameters of Ten Elite Cocoa Clones (Theobroma cacao L.)

“…However they concur with Effendy et al (2013) as some clones like C20, C1 and C8 exhibited high grafting success using budding compared to top grafting. These results are similar with those of Tesfaye et al (2014) who found that in coffee, the grafting techniques influences vegetative growth parameters and can be used as a criterion to screen precocity materials. Most clones exhibited high grafting success when top grafting was used and it was proposed therefore in this study that this should be adopted for grafting the elite cocoa clones in the study areas.…”

Exploring the genetic variability in water use efficiency: Evaluation of inter and intra cultivar genetic diversity in grapevines

“…Interesting variability for WUE was already published for potato [47] coffee [48], and poplar clones [49]. Even though is not matter of this work to identify the genetic basis of such variability, it seems now affordable to do it in near future.…”

Review on Role of Proline on Coffee Under Drought Conditions

“…Clones IC-6 and IC-3 are drought tolerant than other clones due to higher proline accumulation (Table 1), the drought tolerant mechanisms could be linked to osmotic adjustment due to more accumulation of proline. In Figure 5 leaf proline concentration of all the clones decreased when the plants were re-watered (Tesfaye et al, 2014). Tesfaye et al (2014).…”

“…In Figure 5 leaf proline concentration of all the clones decreased when the plants were re-watered (Tesfaye et al, 2014). Tesfaye et al (2014).…”

“…Similarly, several workers have correlated drought tolerance with increase in leaf proline concentration during genotype screening for drought tolerance (Heuer, 1999;Hassan et al, 2003). Increase in proline accumulation in leaves of drought-stressed coffee plants was associated with decrease in leaf water potential, and thus a mechanism of osmotic adjustment in cells or maintenance of turgidity to overcome the stress (Tesfaye et al, 2014).…”