Nematicide Efficacy, Root Growth, and Fruit Yield in Drip-irrigated Pineapple Parasitized by Rotylenchulus reniformis.

A 3-year field trial near Kunia, Oahu, Hawaii, was conducted to evaluate four nematicide treatments for efficacy against Rotylenchulus reniformis in drip-irrigated pineapple (Ananas comosus L. (Merr.)). The treatments were (A) preplant fumigation with 1,3-dichloropropene (1,3-D) (336 liter/ ha) and postplant drip application of fenamiphos (3.4 kg/ha) with restricted irrigation, (B) preplant 1,3-D only, weekly irrigation, (C) 1,3-D fenamiphos, weekly irrigation, and (D) postplant fenamiphos only, weekly irrigation. Fenamiphos was applied at 3-month intervals for 1 year after planting in three treatments. Although nematode populations increased in all treatments 1 year after planting, no differences in fruit yield were detected among treatments in the first (plant crop) harvest 19 months after planting. In the second (ratoon) crop (33 months after planting) significant yield differences, larger fruit size, and greater root biomass were obtained in the dual nematicide treatments. Root biomass increased continuously throughout the crop cycle, was greatest near the drip line, and showed a shallow depth distribution (30-40 cm). Rotylenchulus reniformis populations and fenamiphos concentrations were negatively correlated in soil profiles taken 13 months after planting. In the absence of postplant fenamiphos applications, nematode numbers were positively correlated with root biomass.

Photosynthetic pathway and biomass energy production.

The current interest in locating new or alternative sources of energy has focused attention on solar energy capture by crops that can be subsequently utilized as a substitute for fossil fuels. The very high productivity of sugarepane and the fact that it accumulates sugars that are directly fermentable to alcohol may have caused seemingly less productive crops to be overlooked. We show here that recoverable alcohol from achievable commercial yields of pineapple can actually equal that of sugarcane, with the pineapple crop requiring only a fraction of the water used by sugarcane. Pineapple is well adapted to the subhumid or semiarid tropics and thus is particularly well suited for exploiting large areas not now under cultivation with any crop of commercial value.

Carbon Dioxide Production by Dry Grain of Zea mays.

Use of the gas chromatograph and a mercury-to-glass sealed respirometer adapted for gas syringe sampling, allowed the rapid, accurate characterization of CO(2) evolution rates from live and from dead-sterile Zea mays L. grain dried to moisture levels of 12.6 to 1.4%. The live grain at the lowest moisture level showed an elevated rate inconsistent with the exponential increase in rate of CO(2) evolution with increasing moisture found for maize with moisture contents from 4 to 12.6%. At the lowest moisture level, rates of CO(2) evolution from dead-sterile grain were greater than for live grain. Moisture had no effect on CO(2) evolution from dead-sterile grain. Increasing temperature and increasing levels of O(2) in the storage atmosphere resulted in increased rates of CO(2) evolution from both live and dead-sterile maize. CO(2) production rates from live and from dead-sterile grain decreased with increasing storage time, even though respirometer CO(2) concentrations were less than 1% at the end of the experiment. Our results indicate that CO(2) production is not a dependable measure of respiration in dry seeds. Other experiments indicate that oxygen absorption also is not reliable in maize grain.