Awad, Mohammad Hammad

Ismail, Mohd Razi

Universiti Putra Malaysia Institutional Repository

UPM Research Report 1998: Volume 2ENHANCEMENT OF MANGOSTEEN WATERRELATIONSMohd Razi Ismail and MohammadHammad AwadFaculty of AgricultureUniversiti Putra Malaysia; 43400 UPM,Serdang, Selangor,MalaysiaKeywords:'mangosteen, water deficit, .ABA,'gas ex-change, growth.Introductionone of the mostfactorsdeterminingthe establishment andproductivity of crop plants is water deficit, which might elicitseveral morphological, physiological and biochemical modi-fications (Hsiao, 1973). Transplants of different crops oftensubjected after transplanting to period of dehydration. Par-ticularly under field conditions (Aloni et al. 1991). It is quiteoften that under conditions of high evaporative demand andshortage of rain or supplementary irrigation to observesymptoms of wilting and growth retardation following trans-planting. The recovery of seedlings from the transplantingshock depends largely upon the prevailing conditions and theability of the crop to resume growth under such conditions.Mangosteen is well known that has a slow rate of growth andhas a very long juvenile growth phase. Not much work re-garding this promising crop. The present study investigatedthe effects of hydrogel, abcisic acid (ABA) and methanol fo-liar application in enhancing the growth and water relationsof mangosteen seedlings under water deficit conditions.Materials and MethodsUniform seedlings of mangosteen were selected andtrans-planted in clay pots containing 25 kg of soil mixture. The ex-periment was performed in a randomised complete block de-sign with, four replications. The plants were irrigated to thepot capacity for 15 days after which they were divided intotwo groups. Control plants were irrigated to the pot capacitythroughout the experimental period. Stress treatment applied, by withholding irrigation for 10 days. Part of the stressedplants received daily spray with ABA or methanol until run-off and the third part remained without spraying. Anothergroup of plants received 100 g of .hydrogel at the course oftransplanting and the beginning of the treatment received noirrigation for'10 days. Gas exchange data, elongation of leafand vegetative growth were recorded throughout the experi-mental period which last 3 months later at a 7-day interval.62Results-and DiscussionThe data obtained showed that water deficit resulted in de-crease in stomatal conductance, photosynthetic rate and 'leafwater potential of all stressed plants regardless of the treat-ment applied. This decrease was found as early as day 3 afterwater was withheld from the plant. After 7 days of droughtno effect could be detected in leaf area, plant height, leafnumber, or plant fresh weight between all stressed treat-ments. Similar findings were reported (Mohd Razi et al.1994,Mohd Razi and Awang, 1992). However, when the droughtperiod prolonged as in day 10, leaf elongation rate, formationof new leaves, plant fresh weight was shown to be affected ascompared with that of control. These data indicated that theearly effect of stress appeared to be in stomatal conductanceand photosynthetic rate which in turn affect the amount ofassimilate production required for growth and developmentof the leaves. After re-watering plants recovered their gas ex-change components at slow rate. ABA treated plants showedlow stomatal conductance values but at did not accompaniedwith similar reduction in photosynthetic rate as comparedwith that of methanol or, hydrogel treated plants. These re-sults were in agreement with (Bradford and Hsiao, 1982;Razi and Davies 1997). Death of seedlings was observed inwater stress and hydrogel treated plants, while those receivedABA application no death was observed among the seed-lings. The stressed plants leaves initially showed symptomsof leaf tip firing creeping .inwards towards the midrib and theleaf drop. At the end of drought cycle 3 all water stressedplants except that treated with ABA and to some extentmethanol treated plants shed their leaves as a consequencethere were high significant differences between control andstress plants in fresh' weight, dry weight and effective, plantleaf area. This was probably due to tissue dehydration, How-ever, ABA treatments promoted the water relation of theplants, similar results were obtained by Rashke (1975). 'ConclusionsThe findings presented in this study revealed 'that man-gosteen trees were very sensitive to water deficit. The growthand development of mangos teen seedlings were severely af-fected. Using ABA as a foliar spray at a rate of 50ppm proofto reduce the mortality rate under the conditions of this ex-periment and ameliorate the internal water status of theplants grown under water deficit conditions. 'Contact authorfor references cited inthetext,Supported by IRPA Grant 01-02-04-0039

Enhancement of mangosteen water relations

http://psasir.upm.edu.my/18173/1/Enhancement%20of%20mangosteen%20water%20relations.pdf

Enhancement of mangosteen water relations

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