Moderating factors

Latitude Elevation Techniques (houses, mulches) Climate, geography

Commercial requirements Grower's decisions

Quantity of C02 assimilated wuai liny ui ouj i

Proportion of C02 fixed by CAM

Stomatal opening pattern

Plant morphology Specific leaf area Leaf weight ratio Dry-matter content

Susceptibility to forcing Natural floral induction

Fruit development rate ■

Stem starch accumulation

Sucker development

Sucker growth -

Sucker position

Plant growth rate

Transpiration Consumptive use of water

Forcing to harvest interval

Possibility of one or more ratoon crops ^ Planting to first ratoon harvest interval

Propagule mass

Planting to forcing interval

Plant mass at forcing

Forcing success

Fruit weight

Yield

^ Cycle duration

Total soluble solids Skin colour Multiple crowns

Titratable acidity Flesh colour Collar of slips Aroma Internal browning Fungal diseases

Green ripe fruit Storage life

^ Fruit quality

Fig. 5.17. Flow diagram summarizing the effects of environmental factors, but mainly temperature, on pineapple growth and development.

the complex interactions between weather and CAM in carbon assimilation, water economy and growth processes. The effect of temperature on leaf photosynthesis is reasonably well understood, but it is still hazardous to extrapolate this knowledge to the effect of temperature on crop growth. Leaf photosynthesis is apparently saturated at low irradiance, but crop productivity nevertheless seems to respond to total irradiance, as well as to the fraction intercepted by the canopy. This is due in part to the high LAIs sustained at high planting densities. Also, although pineapple has one of the highest WUEs among cultivated crops and can survive severe drought, the reduction in crop growth due to water stress makes irrigation profitable in many areas.

We show here that, despite a significant amount of research on pineapple, it is still difficult to understand and simulate the effects of weather on yield by linking weather variables to physiological processes.

There is much opportunity for basic research on pineapple to characterize the effects of irradiance and temperature on carbon assimilation, dry-matter partitioning, reproductive physiology, yield and fruit quality. Only when some of these important issues are resolved will it be possible to understand the complex interactions between weather and physiology. Although prediction of pineapple growth and development as a response to the main environmental factors is now possible in some conditions (Zhang et al., 1997), many factors affect the accuracy of such predictions. A comprehensive understanding of the effects of environmental variables on pineapple growth and yield is essential if the accuracy of growth models is to reach the point where it will be possible to satisfactorily predict harvest date and yield. When sufficient data are collected, it may be possible to use growth models to make crop-loss assessments for the several important pest and disease problems that reduce crop productivity.

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