Cultivation of asparagus as an annual crop in the tropics: growth, spear yield and -size of two cultivars harvested at different plant age

In and subtropical regions, asparagus is cultivated as a perennial crop; respectively one year old seedlings are transplanted to the field and spear harvesting starts in the spring of the second year. During the summer this crop grows leaves, producing plant reserves for growth and their winter dormancy. Such a crop possesses a production cycle of more than 10 years. In the tropics the asparagus crop grows faster and does not have any dormancy period and harvesting continuously causes both spear yield and quality to decline rapidly. More efficient spear yield could be attained by treating this crop as an annual crop rather than intensive cultivation over longer periods of time. Harvesting spears of annual crops could commence when spear diameter reaches marketable size (>0,8 cm), while smaller size spears are left to grow for photosynthesis. In the warm and humid conditions of the tropics spears reach marketable size about 3 months after transplanting. However, harvesting spears too early caused growth stress, while harvesting too late resulted in a lower yield. The objective of this experiment was to study the effect of different harvesting time (plant age) on plant growth, spear yield and size of two cultivars, respectively ‘Atlas’ and ‘Jaleo’. The experimental design used was a split-plot design with four replications. Four months old seedlings were transplanted into a ditch, prepared on a 30 cm high soil bed, harvesting of marketable spears were conducted daily starting from 12, 15 and 18 weeks after transplanting for a period of 12 weeks. The ‘Jaleo’ cultivar grew stronger during the early stages of growth than did ‘Atlas’, but its spear yield was slightly lower. Spear yield and size diagrams were compared and discussed.