Forage yield and structural responses of spineless cactus ‘Orelha de Elefante Mexicana’ at different planting densities

ABSTRACT. The objective was to evaluate the forage yield and structural responses of spineless cactus ‘Orelha de Elefante Mexicana’ (OEM) (Opuntia stricta (Haw.) Haw) at different planting densities. The experimental design was a randomized block with five treatments and four replicates, during two production cycles of 12 months each. The evaluated densities were 20,000; 25,000; 33,333; 50,000; and 100,000 plants ha-1. The increase in planting density caused a linear reduction in plant height, width, and mass, as well as in number of primary, secondary, tertiary, and overall cladodes. It also caused a linear increase in cladode area index, dry and green yield, water use efficiency, and forage accumulation rate. The increase in planting density promoted a quadratic effect on cladode thickness and dry matter content. Cladode thickness decreased with planting densities up to 47,500 plants ha-1 and increased from this point onwards. As for dry matter content, there was an increase up to the planting density of 61,428 plants ha-1 and a decrease from this point onwards. The increase in planting density of spineless cactus ‘Orelha de Elefante Mexicana’ caused changes in structural responses and in forage yield. The use of greater planting densities increased forage yield.

摘要：本研究旨在评估不同种植密度下无刺仙人掌（spineless cactus）‘墨西哥象耳’（Orelha de Elefante Mexicana，简称OEM）[梨果仙人掌（Opuntia stricta (Haw.) Haw）]的饲草产量与结构响应。试验采用随机区组设计，设置5个处理、4次重复，覆盖2个各为期12个月的生产周期。供试种植密度分别为20000、25000、33333、50000及100000株·公顷⁻¹。种植密度提升会导致植株株高、冠幅及单株质量呈线性下降，一级、二级、三级茎片（cladode）数量及总茎片数亦呈线性减少；同时，茎片面积指数、干鲜产量、水分利用效率及饲草积累速率均呈线性提升。种植密度提升对茎片厚度与干物质含量存在二次效应：当种植密度升至47500株·公顷⁻¹时，茎片厚度随密度增加而降低，此后则随密度升高而增加；对于干物质含量，当密度升至61428株·公顷⁻¹时，其含量随密度增加而升高，此后则随密度升高而降低。无刺仙人掌‘墨西哥象耳’的种植密度提升会改变其结构响应与饲草产量，更高的种植密度可提升饲草产量。