There is no such thing as cropping along row or column, the second parameter in imcrop function is a rectangle [xmin ymin width height] i.e. the bounding box of the subimage that you want to crop out of your image.
So if your code crops along the column then your 'thisBlobsBoundingBox' variable is what is telling the function to crop along the column. Go through your 'blobMeasurements', see how it is defined and change it accordingly.
For example: For an image of size 100 X 100.
subimage1 = imcrop(image, [0, 0, 100, 50])
subimage2 = imcrop(image, [0, 50, 100, 50])
will divide the original image along the row (horizontally) and subimage1 and subimage2 will hold both the cropped parts of the image.
Have a look at this documentation: Crop an Image and also at this: imcrop for further reference.