Growth and yield of 3 hybrid papayas (Carica papaya L.) under mulched and bare ground conditions

At Yarwun (151.3 degrees E, 23.75 degrees S), Australia, papaya Hybrid 29 y ielded twice as much fruit as Hybrid 11 and 30% more than Hybrid 13. The pl ots mulched with coarse grass hay yielded 50% more fruit than the plots wit h bare ground. The highest yielding treatment, Hybrid 29 + mulch, averaged the equivalent of 81 t/ha.year over the 16.5-month harvest period. The yiel ds were achieved in spite of inadequate water supply due to drought and the loss of 877 plants from 1441 plant positions (4 plants per position) due t o the 3 phytoplasma diseases; dieback, yellow crinkle and mosaic. Hybrid 29 produced higher yields than the other hybrids by flowering early on shorter plants with thicker stems and setting more fruit that commenced lower down on the stem. Hybrid 13 was intermediate in size and the amount o f fruit setting between Hybrid 29 and Hybrid 11 but was the slowest to flow er and set fruit. Hybrid 11 had the thinnest and tallest stems, flowered at an intermediate time between the other 2 hybrids and produced fewer flower s and fruit resulting in the lowest yield. Mulching increased stem height and thickness, promoted earlier flowering an d increased fruit set, yield and average fruit weight.