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For optimization of potato mini-tuber production through aeroponics, an experiment was conducted for the standardization of hardening methods for micro-plants in the aeroponic unit of Central Potato Research Institute, Shimla, HP, India. Three hardening methods were used: planting in pro-trays, acclimatization (1 week) and direct transplanting. Early tuberization was recorded when the plants were hardened in pro-trays. However, percentage survivability, number of tubers per plant and number of harvests were significantly better when the micro-plants were hardened by gradually acclimatizing to the natural climatic conditions (1 week).

Mini tubers are the starting materials of a disease-free seed potato production scheme. Low multiplication rates as well as non-homogenous tuber size distribution are considered the main constraints of a conventional mini tuber production system. In recent years, an aeroponics production system has been developed to overcome the aforementioned problems. It has previously been observed that this system allows multiple harvests with an average yield of 20–50 mini tubers per plant. Several factors, such as cultivar, planting density, nutrient composition of the mist solution, spraying interval and duration and lighting also affect both tuber number and tuber size. However, less attention has been paid to the association of these factors with the aeroponics system. This paper highlights the importance of planting density effect on conventional and aeroponics system. The mini tuber production performances of three potato cultivars (Hermes, Marabel and Sante) were compared at four different planting densities (25, 50, 100 and 200 plants/m2) under both conventional and aeroponics systems in two production cycles. The number of tubers per plant increased with decreasing planting density, being highest at 25 plants/m2 and lowest at 200 plants/m2 for both cycles. Mean tuber number in the aeroponic system was 19.85 tubers per plant at 25 plants/m2 and 13.20 tubers per plant at 200 plants/m2. As the number of tubers per plant decreased, so did their size. As planting density increased, tuber yield per plant both in aeroponics and conventional system decreased, but in general, tuber yield per plant was higher in aeroponics than in the conventional system. In the 1st cycle, the number of tubers per m2 for Hermes, Sante and Marabel was 290, 364 and 334, respectively, in the conventional system and 787, 1021 and 1168, respectively, in the aeroponics system. Similar numbers were recorded in the 2nd cycle. The average tuber weight was higher in the conventional than in the aeroponics system. Tuber yield/m2 in this study varied from 5.9 to 9.3 kg/m2 in the aeroponics system, about twice as high as in the conventional system.

We investigated the effect of inoculation with the plant-growth-promoting rhizobacterium Azospirillum brasilense Sp245 under aeroponic conditions on the quality and performance of minitubers of potato (Solanum tuberosum L. cvs. Nevsky and Kondor). In vitro-grown microplants were planted in an aeroponic system, and after 3 weeks of growth, the bacteria were added to the potato nutrient solution. We evaluated the effect of inoculation on the potato growth variables, minituber yield and minituber starch content. Root-associated bacteria were detected by confocal microscopy, and their numbers in the plant growth medium were monitored by enzyme-linked immunosorbent assay. Cells of A. brasilense Sp245 remained on roots during plant growth and were eliminated from the nutrient solution in the aeroponic system within a week after inoculation. Inoculation brought about statistically significant increases in shoot height (16%) and in leaf blade number (14%). The number of minitubers increased by 40% in Kondor plants and by 60% in Nevsky plants, and their yield per square metre increased by an average of 17% in both cultivars. Inoculation also increased the size of starch grains in the amyloplastids (by 12%) and the starch content of minitubers (by 1.5 times). The plant-bacterial association developed in this study was active under aeroponic conditions. This report is the first to show that A. brasilense Sp245 promotes the growth, development and performance of potato and helps to increase the quality of minitubers, thereby contributing to the efficacy of potato seed tuber production.

Three hydroponic systems (aeroponics, aerohydroponics, and deep-water culture) were compared for the production of potato (Solanum tuberosum) seed tubers. Aerohydroponics was designed to improve the root zone environment of aeroponics by maintaining root contact with nutrient solution in the lower part of the beds, while intermittently spraying roots in the upper part. Root vitality, shoot fresh and dry weight, and total leaf area were significantly highest when cv. Superior, a medium early-maturing cultivar, was grown in the aeroponic system. This better plant growth in the aeroponic system was accompanied by rapid changes of solution pH and EC, and early tuberization. However, with cv. Atlantic, a mid-late maturing cultivar, there were no significant differences in shoot weight and leaf area among the hydroponic systems. The first tuberization was observed in aeroponics on 26–30 and 43–53 days after transplanting for cvs Superior and Atlantic, respectively. Tuberization in aerohydroponics and deep-water culture system occurred about 3–4 and 6–8 days later, respectively. The number of tubers produced was greatest in the deep-water culture system, but the total tuber weight per plant was the least in this system. For cv. Atlantic, the number of tubers 30 g between aerohydroponics and aeroponics. For cv. Superior, there was no difference in the size distribution of tubers between the two aeroponic systems. It could be concluded that deep-water culture system could be used to produce many small tubers (1–5 g) for plant propagation. However, the reduced number of large tubers above 5 g weight in the deep-water culture system, may favor use of either aeroponics or aerohydroponics. These two systems produced a similar number of tubers in each size group for the medium-early season cv. Superior, whereas aerohydroponics produced more tubers than aeroponics for the mid-late cultivar Atlantic.

Two different cultivation systems, aeroponics and hydroponics in greenhouse beds, were compared for the production of potato minitubers. Plants in the aeroponic system showed increased vegetative growth, delayed tuber formation and an extended vegetative cycle of about seven months after transplanting. Therefore in 1999, two production cycles were obtained with the hydroponic system, but only one with the aeroponic system. However, compared with total production in hydroponics, the tuber yield per plant in the aeroponic system was almost 70% higher and tuber number more than 2.5 fold higher. Average tuber weight was reduced by 33% in the aeroponic system. Advantages and possible problems with the aeroponic system for minituber production are discussed.