Abstract From Young Scientist : The Physiological Response Of Grafted Sweet Potato Plants Under Water Limited Conditions

By: Saraswati Prabawardani
Faculty of Agriculture and Agriculture Technique Papua State University

In the highland areas of Papua, drought and frost are the major problems for sweet potato production. Drought and frost occur yearly and devastate crops, threatening the lives of the people in the area. Due to the effect of El Niño, prolonged and severe drought occurred in 1997. As a consequence, many sweet potato crops died and lost (Prain and Widyastuti, 1998; Ballard, 1999).

Improvement of plant productivity under water stress needs an understanding of physiological mechanisms by which water stress affects plant growth. Sexual breeding strategies have not been very effective, as incompatibility is common in the sweet potato. Traditionally, farmers have selected seedlings from natural (segregating) populations, for specific traits, as sexual breeding is long-term job requiring a lot of resources and has often been unsuccessful for sweet potato. Grafting may offer a short-term solution by combining the desirable characteristics of different cultivars into one plant. Objective of the study was to observe the physiological aspects of rootstocks and scions from both drought tolerant and susceptible sweet potato cultivars under water limited conditions.

Results showed that grafting between two cultivars with compatible scions and rootstocks is possible. The compatibility of the grafted combination between a Lole scion grafted and a Wanmun rootstock fulfils the criterion for a drought tolerant strategy and good storage root yields under water stress conditions. The ability of this grafted combination to produce high tuber yields was associated with low rate of transpiration and high water-use efficiency. In addition, compatibility and good alignment across the grafted union provided ready movement of assimilates from leaves, and easy transport of water and inorganic substances from roots. Grafting of appropriate sweet potato materials allows the option of new farming systems to be developed so that the indigenous people of drought-prone environments, where sweet potato is the staple diet, can use the benefits to flow from the results of the present study.