Alfalfa (Medicago sativa L.) pollination service estimation by tripped flowers quantification

Biotic pollination directly affects yield of most of crop species. Therefore, monitoring the pollination service in a crop field is very important, although it rarely occurs. Certain pollination mechanisms, such as the explosive mechanism of flowers, would allow farmers to estimate the crop yield quickly and efficiently. The objective of this study is to evaluate a methodology for estimating the pollination service in crops with explosive pollination mechanism through the quantification of tripped flowers. For this, we used 16 alfalfa (Medicago sativa) lots in eight fields located in the Valle Bonaerense del Río Colorado, where we conducted pollination experiments and assessed the proportion of tripped flowers (visited) per inflorescence and the plant reproductive success (estimated as fruit set). Our results showed that a) in alfalfa, non-tripped flowers have a very low probability of becoming fruit, b) a single effective visit is sufficient for fructification, and c) successive visits do not increment the probability of fruit formation. On the other hand, we demonstrated that the proportion of tripped flowers is positively related to fruit set. Our results evidence that the assessment of tripped flowers can be an efficient tool to quantify the pollination service in a crop with an explosive mechanism. Although this methodology does not explain the causes of fructification deficiency, this tool may become the first step in crop problems detection, without neglecting the long-term studies that will improve pollination service in an effective way.