Journal de biochimie et de physiologie végétales
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Mechanical and Hormonal Canopy Manipulation Strategies for Improving Solanum tuberosum Andigena Tuber Yield under Limited and Unlimited Water and Nitrogen

Isaac Fandika

Solanum tuberosum ssp. (Andigena) possesses good processing, health attributes and potential genetic diversity for breeding. However, they are handicapped by low yields due to large vegetative growth and loads of tubers per plant. This field study examined the consequences of canopy manipulation on S. andigena tuber yield, dry matter partitioning and water use efficiency (WUE) under limited and unlimited water and nitrogen (N) environment. The experiment was conducted at Massey University, Palmerston North, New Zealand from October 2010 to April 2011 comparing canopy manipulations subjected to two water and N regimes in a RCBD split-split plot design with four replicates. Solanum andigena ssp known as Tutaekuri was mechanically topped and foliar sprayed with CCC for 25-50 days from planting compared to a normal growing as a control. The water regimes were irrigation and rain-fed while applied. Topping and spray of CCC improved water use, tuber yield and WUE by increasing partitioning of dry matter to the roots and tubers. The 25-30 CCC schedule and mechanical topping adapted plants to water stress by partitioning more assimilates to the roots while 25-50 CCC schedule impeded roots development. Exclusion of N enhanced WUE while irrigation had no effect on WUE. The study suggested that excessive vegetative growth is responsible for low yields and low WUE in S. andigena and that it can be reversed by mechanical topping and CCC spray and N exclusion.