Safflower (Carthamus tinctorius) is an annual oilseed crop belonging to the Asteraceae family. It is adapted to semiarid growing conditions and could have expanded potential as an alternative, multipurpose crop in central Argentina and other semiarid regions. Agronomic and ecophysiology research of safflower is needed to promote its cultivation and economic potential. An accurate, standard scale describing phenological growth stages is needed to facilitate the crop management and research. We describe phenological growth stages of safflower plants from seed germination to harvest maturity according to the codes of the extended BBCH scale, a scale widely adopted throughout the world for the description of growth developmental stages of weeds and crops. This scale uses a two-digit code, where the same code is applied to the same growth stages of different plant species. For each code, a description based on easily observable external morphological characteristics is given. This work is the first description of safflower growth stages according to the codes of the extended BBCH scale. The codification proposed here provides an accurate and simplified approach to identify the safflower growth stages. This will provide a useful tool for farmers and researchers facilitating scientific communications at an international level.

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The increase in sunflower yield due to the active participation of honey bees (Apis melifera L.) in crop pollination has been demonstrated in previous studies. However, this fact is more evident in earlier commercial hybrids. There are reports that suggest that bees are not required in modern commercial hybrids where a high level of self-compatibility occurs.The purpose of this study was to define formation capacity of fully developed fruits (FDF) and incompletely developed fruits (IDF) in two modern sunflower hybrids exposed to open and closed pollination.Two hybrids, one of half cycle and the other of short cycle, labelled HA and HB respectively, were submitted to two pollination regimes: auto-pollination (bagged treatment) where the heads were covered with mesh bags from the first anthesis (FA) to the last anthesis (LA), avoiding the action of pollinators and open pollination (open treatment). The study was conducted during three consecutive years in two different locations. In the first year, the experimental plots were located at the Chacra experimental Barrow (Tres Arroyos; 38°20' S; 60°13' W) and in the second and third year at the experimental field of Universidad Nacional del Sur, (Bahía Blanca; 38°45' S; 62°11' W), reaching an average plant density of 60.000 plants/ha. During the second year treatments were conducted only on the HA and during the third year only on the HB.The number of FDF and IDF, in the three experiments on both sites did not show significant differences among treatments. Nevertheless, a non-significant different response in the number of FDF and IDF was observed during two years, probably as a result of changes in environmental conditions during the anthesis period.We conclude that, due to the effect of a high level of self-compatibility, no differences in the generation of fully developed fruits can be observed when plants of modern commercial sunflower hybrids are excluded from pollinators.

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