Pod and seed growth and development of narrow-leafed lupin in a water limited mediterranean-type environment

Understanding the growth and development of reproductive organs is an important basis for investigating causes of yield variation. In narrow-leafed lupin, pods are borne on terminal racemes on the main shoot and branches. These shoots newer and set pods first on the main shoot and then on the first, second and subsequent orders of branching. This leads to complex temporal and spatial relations in the growth of pods and seeds throughout the plant. This study describes the development and morphology of pods and seeds and investigates relationships in the patterns of pod and seed filling on the branch orders. Despite the sequential setting of pods, their phases of rapid growth were almost synchronous and they reached maturity at almost the same time (i.e. durations of filling became shorter as the branch order increased). The progressively shorter durations of filling were accompanied by higher growth rates so that pod and seed weights on most branches were similar. Pod and seed filling occurred much faster and the durations of filling were shortened in lupins grown in an environment where water availability decreased rapidly after the beginning of pod and seed filling.