Inbred and mutant corn lines grown indoors often don’t yield adequate seed, slowing progress of the project. The difference between 75 and 100 seeds on an ear may seem negligible compared to a hybrid ear with 600 seeds, but just may make the difference between having enough seed for the next round of breeding or not. We address lighting and plant density together in this document because of their relationship to light reaching the lower canopy, which has been shown to correlate to seed yield. We’ve learned the hard way that the same lighting that produces excellent vegetative growth may not produce adequate seed yield if the plants are too closely spaced. Ears abort, silks fail to emerge from ears or emerge long after pollen shed.
It is generally accepted that if other environmental stresses are reduced, the limiting factor in corn yield is light. We believe the growing system that we propose eliminates water and nutrient stress, so maximizing light should be a focus to improve seed yield. This is a challenge for plant growth facilities. Over the course of a day, we have measured a 40% loss in daily light integral (solar accumulation) in our modern glass greenhouses due to glazing and superstructure. We took light intensity readings inside a cornfield on an overcast July day (1250 μmol/m2/s) and were surprised to measure 314 μmol/m2/s at the lowest leaves of the stalks. In a greenhouse, we may get a third of that intensity. In a growth room, where light source is directly above with little penetration into the tall canopy from the sides, we’ve measured light at soil surface below 10 μmol/m2/s. Field research that supplemented light to lower canopy (Ottman and Welch, 1988) increased kernels per ear by 14% and number of ears in the plot by 25%. This was accomplished by adding only 121 μmol/m2/s. From this, we suggest that a lot could be gained by lighting and plant spacing strategies that increase light to lower canopy.
None of our studies compared lighting or plant density, but we will report on what we have observed, studies we have collaborated with, and consensus from other facilities. It is by no means comprehensive.
It is generally accepted that if other environmental stresses are reduced, the limiting factor in corn yield is light. We believe the growing system that we propose eliminates water and nutrient stress, so maximizing light should be a focus to improve seed yield. This is a challenge for plant growth facilities. Over the course of a day, we have measured a 40% loss in daily light integral (solar accumulation) in our modern glass greenhouses due to glazing and superstructure. We took light intensity readings inside a cornfield on an overcast July day (1250 μmol/m2/s) and were surprised to measure 314 μmol/m2/s at the lowest leaves of the stalks. In a greenhouse, we may get a third of that intensity. In a growth room, where light source is directly above with little penetration into the tall canopy from the sides, we’ve measured light at soil surface below 10 μmol/m2/s. Field research that supplemented light to lower canopy (Ottman and Welch, 1988) increased kernels per ear by 14% and number of ears in the plot by 25%. This was accomplished by adding only 121 μmol/m2/s. From this, we suggest that a lot could be gained by lighting and plant spacing strategies that increase light to lower canopy.
None of our studies compared lighting or plant density, but we will report on what we have observed, studies we have collaborated with, and consensus from other facilities. It is by no means comprehensive.
For more information: http://www.seedbuzz.com/knowledge-center/article/optimizing-green-house-production
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