Drought stress can have substantial negative impacts on cocoa plant growth until affect the death of plant. The present study aimed to determine theeffect of drought stress on the some physiological characters of cacao (Theobroma cacao L.) seedlings. The research was carried out at the Indonesian Coffee and Cocoa Research Institute, Jember, East Java, Indonesia. This research was conducted from January–December 2017. The experiment was designed by using completely randomized block design with two factors and with three replications. The first factor was clones, namely ICS 60, Sulawesi 1 and KW 641 clones. The second factor was interval of watering treatment, namely watering every 2 days (control/adequate water condition), watering every 5 days (moderate stress), and watering every 8 days (severe stress). Result of this study concluded that drought stress reduced the growth of cocoa seedlings, mainly as a result of reducing photosynthetic activities in all stressed cocoa clone seedlings. Under drought stress, KW 641 and Sulawesi 1 had higher leaf area, chlorophyll a, chlorophyll b, total chlorophyll content, relative water content, and photosynthetic rate than ICS 60 clone.

ENSO (El Nino Southern Oscillation) occurring in 2015 in Indonesia caused drought stress and the decrease in the percentage of production and even death of plants. One effective and relatively inexpensive way of reducing damage and economic losses due to drought is the availibility of tolerant cocoa. The objective of this research was to obtain tolerant clones based on morpho-physiological characters under drought stress. The experiment was conducted in Kaliwining Experimental Station of Indonesian Coffee and Cocoa Research Institute (ICCRI) during dry season (El Nino period with 5 consecutive dry months, from May to October 2015). Stomata, proline, leaf water status was measured at the peak of dry season on tested cocoa clones. The cocoa clones that predicted tolerant against to drought stress were KW 641, KW 514, KW 535, KW 619, and KW 516, whereas the cocoa clones that predicted susceptible under drought stress were KW 609, KW 614, KW 635, KW 606, and KW 651. The treatment clones had higher values of RWC, leaf proline content, narrower width and length of stomata openings, but smaller value of WSD compared to susceptible clones. Meanwhile, the character of leaf thickness might not significanly different to the character of drought tolerance.

Currently, vascular streak dieback (VSD) attacks have widespread in areas of the center of cocoa (Theobroma cacao L.) production, especially in Sulawesi. Salicylic acid and benzoic acid are part of phenol compounds reportedly acts as bioimmunoregulator in increasing of plant resistance to that pathogen. The objective of this research was to investigate effect of exogenous salicylic acid and benzoic acid applications to VSD disease attack on cocoa seedlings. The research was conducted at Indonesian Coffee and Cocoa Research Institute, Jember, East Java. This experiment designed using randomized completely block design with three replications. The treatments included concentrations of salicylic acid in 0.5 mMol, 1 mMol, 2 mMol; benzoic acid with concentration 0.5 mMol, 1 mMol, 2 mMol; and control (water spray). Observations were based on the incidence and severity damage of disease, plant height, stem diameter, number of leaves, stelate trichome, chlorophyll, width and length of stomatal apperture, and number of stomata. Exogenous salicylic acid and benzoic acid as phytohormone can reduce disease insidence and severity of VSD. In conclusion, our results indicated that exogenous salicylic acid and benzoic promoted stomatal closure in cocoa leaf by decreasing width-stomatal closure. Salicylic and benzoic acid had no effect to plant height, stem diameter, number of leaves, length of stomatal apperture, number of stomata, and number of stelate trichome.

Reducing budwood number is an efficient effort to overcome problemsrelated with limited scion materials. The objective of this research was to studythe effect of scion budwood number in some clones on the performance of graftedcocoa seedlings. The research was conducted at Kaliwining Research Station,Indonesian Coffee and Cocoa Research Institute, Jember, Indonesia at an elevationof 48 m above sea level. Layout for this study used factorial with 2 factors inrandomized complete block design, with four replications for every treatment.The first factor was clone type, namely MCC 02 and Sulawesi 1; whereas the secondfactor was number of grafted scion budwood, namely one, two, and three graftedbudwoods. There was no interaction between clone and number of scion budwoodfor variables of shoot length, stem girth, content of total chlorophyll, chlorophylla, and chlorophyll b. Meanwhile, there was interaction for stomatal conductanceand stomatal diffusion resistance. Clone significantly affected photosynthesisand stomatal diffusion resistance, while number of scion budwood affected significantlythe shoot length. Photosynthesis activity of MCC 02 was higher comparedto Sulawesi 1. In average, stomatal diffusion resistance of Sulawesi 1 was higherthan MCC 02. The shoot length of one grafted budwood was higher than thetwo or three grafted budwood.

An optimum physiological condition will support high yield and quality of cocoa production. The research was aimed to study the effects of stomatal conductance and chlorophyll content related to cocoa production under three shade regimes.This research was conducted in Kaliwining Experimental Station, elevation of 45 m above sea level with D climate type based on Schmidt & Fergusson. Cocoa trees which were planted in 1994 at a spacing of 3 X 3 m were used in the study planted by using split plot design. The shade tree species were teak (Tectona grandis), krete (Cassiasurattensis), and lamtoro (Leucaena sp.) as the main plots, and cocoa clones of Sulawesi 01,Sulawesi 02, KKM 22 and KW 165 as sub plots. This study showed that there was interaction between cocoa clone and shade species for stomatal conductance where stomatal diffusive resistance of KKM 22 was the best under Leucaena sp.and Cassiasurattensis with the values of 1.38 and 1.34 s.cm -1, respectively. The highest chlorophyll content, stomatal index and transpiration values was under Leucaena sp. shade. There was positive correlation between chlorophyll content and transpiration with pod yield of cocoa. The highest yield and the lowest bean count wereobtainedon Sulawesi 01 clone under Leucaenasp. shade.Keywords: stomatal conductance, transpiration, diffusive resistance, shades trees, clones,pod yield