UNLABELLED • PREMISE OF THE STUDY Evolutionary changes in how flowering time responds to photoperiod cues have been instrumental in expanding the geographic range of agricultural production for many crop species. Locally adaptive natural variation in photoperiod response present in wild relatives of crop plants could be leveraged to further improve the present and future climatic ranges of cu...

The growth responses of a sunflower seedling (Helianthus annuus L.), subjected to repeated inversion, were characterized by time-lapse recording in conjunction with video image analysis. The investigation revealed a characteristic response pattern and established that the directional movement of the seedling is achieved by both inhibition and stimulation of growth in the normal growing regions....

the nutrient deficiency. The apparent narrow temperature range of maximum growth found in the old cultures of Chlorella and Anacystis also seem to be caused by such secondary effects. We have therefore prepared table I from the earliest clear pattern that developed. It should represent the optimum conditions for cultivating these algae. In figure 4 the development of a Chlorella pyrenoidosa and...

Although sunflower was long thought to be the product of a single domestication in what is now the east-central United States, recent archaeological and genetic evidence have suggested the possibility of an independent origin of domestication, perhaps in Mexico. We therefore used hypervariable chloroplast simple-sequence repeat markers to search for evidence of a possible Mexican origin of dome...