Introduction. A study was conducted in India to assess the efficiency of 32P uptake and the feasibility of intercropping using land-use efficiency parameters in a banana-based intercropping system. Materials and methods. Absorption of 32P applied to plants in five-crop, two-crop and sole-crop systems involving banana Musa AAB (‘Mysore’), ginger (Zingiber officinalis Rosc.), turmeric (Curcuma longa L.), cassava (Manihot esculenta Crantz.) and elephant yam (Amorphophallus campanulatus Blume.) was studied in field trials. The experiment was conducted for two years. During the first year, the main crop was planted during October, the main planting season for banana in India, and the intercrops were planted in early May of the next year. In the second year, both the main crop and intercrops were planted in May. Results. Radiophosphorus applied in the active root zone of one of the component species in the mixed crop system was found to be absorbed not only by the treated plant but also by the neighboring plants. Absorption by banana was prevalent. Differential effects of competition were manifested as observed by the relative uptake of 32P. Lower relative uptake of 32P was observed in the main crop banana when simultaneous planting of intercrops was done. Ginger and turmeric were not affected in relation to planting at different stages of the main crop, whereas cassava and elephant yam showed lesser relative 32P uptake when planted later, confirming that different crops in the mixed crop system react differently. Conclusions. The efficiency of different crops in terms of uptake varied with the system of planting. The higher relative efficiency of 32P uptake in a multiple cropping system points to an improved efficiency of uptake and higher dry weight on a per plant basis. It confirms the efficiency and feasibility of the cropping system. Economic analysis emphasizes the concept and proves the viability of the system.

Introduction. Competition between plants on a mat (intramat) and between plants on different clumps (intermat) is quite common in crops such as banana. A study was therefore undertaken to know the extent of intramat and intermat competition using isotopic techniques. Materials and methods. The competition between plants in a mat and between mats were recorded in a combination of three spacings and five physiological phases of sucker retention by giving 32P to an experimental plant using soil injection techniques and monitoring the levels of recovery. The recovery of the isotope was recorded in the applied plant and its daughter (intramat) and in the neighboring border plant and its sucker (intermat). Results. The study revealed that, when 32P was given by soil injection techniques to one plant, it could be recovered in the border plant and its sucker during both years of study. In the first year, activity in initial samplings in border clumps were the highest, with the widest spacing in the experimental plant showing the highest recovery, but a differential pattern of recovery was observed at different samplings in the border clumps. In the irrigated crop of the second year, the highest recovery was observed at the closest spacing in both the experimental and border clumps. With respect to sucker retention at definite physiological phases, the recovery was the highest at the late vegetative phase, the flower bud initiation and the shooting phase. The recovery in the mother plant and its sucker and the border plant and its sucker studied separately gave a measurement of the intramat competition. Conclusion. The differential nature seen with retention phases confirms the requirement and intensity of activity with defined physiological phases and the overall need to evaluate and redefine recommendations, taking into consideration the critical physiological phases.

Introduction. A project was undertaken to study the nutrient cycling from Musa mother plants to daughter suckers based on the physiological stages of the mother plant. It also reports on the dependency or competition at critical stages of flowering and fruiting and the combinations of different densities and sucker retention at different physiological stages of the mother plant. Materials and methods. A combination of three spacings and five sucker retention phases formed 15 treatments. 32P was given through injection into the mother plant pseudostem. The experiment was carried out over two years, the first being a rain-fed crop and the second being under irrigated conditions. Results. Differential aspects of nutrient cycling were observed between rain-fed and irrigated crops with regard to spacing. In the case of sucker retention phases, in the first year, it was retention at fruit maturity, shooting and flower bud differentiation stages which showed higher radioactivity recovery whereas, in the second year, it was the early phases of retention which showed significantly higher recovery. In the case of interaction effects, in the first year, the highest recovery was found in various combinations of spacing with the stages of bud initiation and shooting and, in the second year, the maximum recovery observed was in the combination of the closest spacing with the stage of flower bud initiation. In both years, recovery was observed in the border row plants. Conclusion. The study confirmed that activity extruded out from the treated plant and was absorbed by the border plants, revealing that nutrient sharing takes place in banana. This result opens up another concept that banana recommendation should not only be at an individual plant level but at block or plot level also. Hastening and improving the efficiency of nutrient cycling to the sucker is suggested as a future line of investigation.