Higher yields from small-potted plants.

Higher yields from small-potted plants

Small pots tend to stunt growing plants, much as droughtdoes. But new work at the Agriculture Department's Plant Stress Laboratory in Beltsville, Md., indicates that unlike drought-related stunting, the stunting from root-restricting small pots is not caused by decreased photosynthesis. In fact, given adequate water and nutrition, root-restricted plants conduct comparable photosynthesis and even offer higher yields per volume of soil than nonstressed plants in large pots.

Donald T. Krizek and his colleagues found that they could getthe same number of mature, ripe fruits per plant from tomatoes grown in 3 1/2-inch pots (with 450 cubic centimeters volume) as from tomatoes grown in 11-inch pots (with 13,500 cc volume). While the size of the tomatoes differed--about 5 grams (dry weight) per fruit in the small pots versus 8 g per fruit in the larger ones--roughly three times as many small-potted tomatoes could be grown in the space of a single large-potted plant. So, on a total-yield-per-space basis, the small pots were almost twice as efficient at producing tomatoes, Krizek notes. The trick is to see that the small-potted plants get adequate water and nutrition. His are watered and fed three to six times daily with a microprocessor-driven system. A report on the work will appear this fall in the JOURNAL OF THE AMERICAN SOCIETY FOR HORTICULTURAL SCIENCE.