GROWTH, PHOTOSYNTHETIC COMPETENCE AND OLEO-GUM RESIN PRODUCTION OF GUGGAL (COMMIPHORA WIGHTII) ACROSS SOIL MOISTURE AND NITROGEN GRADIENT

Guggal (Commiphora wightii) is a small tree, widely distributed in the forest of arid western India and Pakistan, which yields oleo-gum resin (guggul). The present study was an attempt to increase the growth rate of guggal with external inputs such as nitrogen and irrigation. Individual guggal rooted cuttings were grown in pots and supplemented with 17 or 34 mg kg-1 nitrogen through urea, potassium nitrate or glycine. However, nitrogen did not have significant effect on the plant growth rate, leaf chlorophyll, photosynthesis rate, and the yield and quality of guggal compared with control. Similarly, rooted cuttings were grown at five different soil moisture regimes (30—10%, at 5% intervals labelled as SM30—SM10). Plants at higher soil moisture depletion reacted by stomatal closure to reduce transpiration rate. Total leaf chlorophyll content drastically declined from 1.5 (SM30) to 0.5 mg g-1 (SM10). Consequently, plant growth rate was hampered significantly with depleting soil moisture. SM30 supported best growth rate as indicated by plant height and leaves per plant. Guggul production declined by 11—20% at SM15—SM10 compared with SM30 but its quality gradually improved with the increase in moisture deficit. Hence, soil moisture will be important in organised farming of this species. Guggal (Commiphora wightii) merupakan pokok kecil yang tersebar luas di hutan di barat India yang gersang serta Pakistan dan menghasilkan resin gam oleo (guggul). Kajian ini merupakan cubaan untuk meningkatkan kadar pertumbuhan guggal dengan manipulasi luaran iaitu kandungan nitrogen serta pengairan. Keratan berakar guggal ditanam dalam pasu yang ditambah 17 mg kg-1 atau 34 mg kg-1 nitrogen dalam bentuk urea, kalium nitrat atau glisina. Bagaimanapun, nitrogen tidak memberi kesan signifikan terhadap kadar pertumbuhan pokok, klorofil daun, kadar fotosintesis dan hasil serta kualiti guggal berbanding dengan kawalan. Selain itu, keratan berakar ditanam pada lima kelembapan tanah (30%—10%, pada selang 5% dan dilabel SM30—SM10). Pokok yang ditanam pada kehilangan kelembapan yang lebih tinggi bertindak balas dengan menutup stoma untuk mengurangkan kadar transpirasi. Jumlah klorofil daun menurun dengan mendadak dari 1.5 mg g-1 (SM30) ke 0.5 (SM10). Akibatnya, kadar pertumbuhan pokok terbantut dengan signifikan apabila kelembapan tanah berkurangan. SM30 memberi kadar pertumbuhan terbaik dari segi ketinggian pokok serta bilangan daun setiap pokok. Penghasilan guggul menurun sebanyak 11%