Yield Responses of Different Alternative Crops to Growth Stage Based Irrigation Management.

Many low input alternative crops are being evaluated in the Southern High Plains (SHP) to diversify cereal based cropping systems. Many of these have different root systems and stress responses. Therefore, better understanding of yield formation in these alternative crops under different water availabilities are needed to fit them in current rotations. Results of two separate trials conducted to assess spring safflower (Carthamus tinctorius L.) and canola (Brassica napus L.) response to critical stage based irrigation management are interpreted from a rotational perspective. Irrigation treatments were 1). Full irrigation (FI), 2). No irrigation at vegetative stage (VS), 3). No irrigation at reproductive stage (RS) and 4). Dryland after crop establishment (DL). Each trial had three different cultivars. Both crops responded differently to skipping irrigation at vegetative or reproductive stages. In canola, RS reduced seed yield by 48 to 54% compared to FI, which ranged between 8 to 14% in VS. In safflower, yield decreases were 19 to 20% in RS and 22 to 25% in VS, respectively. In safflower, heads plant^-1 was the most sensitive yield forming trait, while in canola, both thousand seed weight and pods plant^-1 responded to lack of irrigation. It appears that based on resources available before flowering, safflower sets its sink or yield goal and when stressed for water during reproductive stage, it uses strong root system to secure much needed water. Less sensitive reproductive stage makes safflower a better fit in the SHP compared to canola. During peak irrigation demand time, irrigation from safflower can be directed to main cash crops.