 If the marocca plants happened to die during transport, what would be one logical explanation for why they died based on the conditions they needed to survive in the article?
Captain Hannah climbed painfully down from the Delta Crucis , hobbled across the spaceport to where Beulah and I were waiting to greet him and hit me in the eye. He had foisted those two maudlin mastodons off onto me in one of our earlier deals, and if I had somehow been responsible for his present troubles, it was no more than he deserved. Transshipped seeds invariably failed to germinate, which explained its rarity. The Myporians were usually, and understandably, bitterly, opposed to letting any of the living plants get shipped off their planet. But when I offered them a sizable piece of cash plus a perpetual share of the profits for letting us take a load of marocca plants to Gloryanna III, they relented and, for the first time in history, gave their assent. "When I left, marocca was growing like mad," said Captain Hannah. But our tests showed that the plants had enough tolerance to cause no trouble in the trip in Delta Crucis ." "You'll remember that I warned you that we should take some marocca out into space and solve any problems we might find before committing ourselves to hauling a full load of it?" asked Captain Hannah. If we had gone through all of that rigamarole, we would have lost the franchise. I almost asked him why he had been barricaded in the bathroom of the Delta Crucis , but I figured it was safer to let him tell me in his own way, in his own time. The plastic film kept the water in the hydroponic tanks without any trouble, even in a no-gravity condition. And by the time I had lined up for Gloryanna and Jumped, I figured, like you said, that the trip would be a cakewalk. So I lined up the Delta Crucis perpendicular to her direction of motion, put a once-every-twenty-one hour spin on her to match the rotation rates of Mypore II and Gloryanna III, and uncovered the view ports to let in the light. It gradually brightened until 'noon time', with the ports pointing straight at the light source, and then dimmed until we had ten and one-half hours of darkness. With no gravity for reference, how were the plants supposed to know that the 'sun' was supposed to be moving?" "Of course, first I had to move all the hydroponic tanks from their original positions perpendicular to the axial thrust line of the ship to a radial position.
 An error on the spaceship caused the artificial days and nights to not be equal length.
 The temperature of the environment did not vary enough and was too stagnant for the plants.  The carollas decided to start eating the dingleburys instead of vice versa.  An error on the spaceship caused the artificial days and nights to not be equal length.  The spaceship was not correctly simulating all the seasons that the marocca needed to be subjected to in order to grow.