Daniel O. Caldiz

AGRO-ECOLOGICAL ZONING AND POTENTIAL YIELD OF SINGLE OR DOUBLE CROPPING OF POTATO IN ARGENTINA

Potato is the most important horticultural crop in Argentina and at present 100,000 ha are grown in different regions and seasons. The four possible growing seasons are defined as early (June–October), medium-early (July–November), medium-late (October–March) and late (February–June) and have already been characterized by assessing weather, soil and crop type, yield level and yield determining, yield limiting and yield reducing factors. However, there is scarce or no information on the possibilities of expanding actual crop frontiers, either at regional or national level and on the potential yield of the crop in different agro-ecological zones. Hence, in this work, we (1) characterize agro-ecological zones for potato production, (2) establish potential duration of the crop cycle and potential growing seasons, (3) estimate the potential yield of the crop in these zones and seasons and (4) demonstrate how Geographic Information Systems (GIS) for land evaluation and simulation models that establish potential yield of the crop can be used together to assess possibilities for increasing crop production at regional or national scales. Seven potential growing seasons ranging from 3500°C day were identified for areas where one crop can be grown per year, whereas four areas were identified where there is a potential for a second crop of potatoes. In these areas and seasons, potential tuber yields ranged from 20 Mg ha−1 dry matter. The study identified suitable soils and ascertained the corresponding potential duration of the growing seasons and the potential yield for each of the suitable sites and seasons.

Physiological age index: a new, simple and reliable index to assess the physiological age of seed potato tubers based on haulm killing date and length of the incubation period

Chronological and physiological age of seed tubers have major impacts on potato yields. This paper presents a new, simple and reliable physiological age index (PAI) that considers and reconciles the effects of chronological and physiological age. PAI calculation is based on the haulm killing date of the seed crop (T0) and the end of the incubation period of seed tubers, measured under standardized conditions. The PAI formula is T1/T2, where T1 is the time from haulm killing date (T0 )t o possible planting date and T2 the time from T0 to the end of the incubation period. The PAI expresses physiological ageing of seed potato tubers within a range from 0 (for physiologically young) to 1 (old) tubers. To test the PAI existing data were reevaluated and re-elaborated and specific experiments regarding seed origin and storage conditions for different cultivars were performed during 1994‐1999. The PAI proved useful in assessing differences due to differences in growing conditions, cultivar, haulm killing, seed origin and storage system, and pre-planting treatments. For example, for cv. Spunta 6 days after haulm killing the PAI was 0.025 and after 100-storage days the PAI was 0.56, 0.52 and 0.49 for seed tubers stored in heaps in the field, at relatively high temperatures, natural diffuse light and a cold (48C) and ventilated store, respectively. The PAI is related to ground cover duration and yield of the future crop. For a PAI of 0.55 tuber yield was 55 t ha ˇ1 , while for a PAI of 0.80 tuber yield was 40 t ha ˇ1 . The PAI is easy to measure, non-invasive, objective, reproducible and reliable and could be used for modelling purposes to describe performance of seed tubers. # 2001 Elsevier Science B.V. All rights reserved.

Yield prediction using the SUBSTOR-potato model under Argentinian conditions

SummaryThe use of crop simulation models to predict yield, associated with decision support systems such as Decision Support System for Agrotechnology Transfer (DSSAT), are useful tools to test different management strategies.The potato growth model included in DSSAT is SUBSTOR-potato. To evaluate its performance in Argentina it was calibrated and validated using experimental results from different sites and years. Cultivar-specific coefficients were obtained during calibration. Validation based on several independent sets of field data, including cvs Huinkul, Kennebec, Mailén and Spunta showed good agreement (R2=0.915; n=24) between observed and simulated values in normal ranges of tuber yields. However, when the input parameter maturity date was not taken into account, tuber yields were overvalued due to an overestimation of LAI values during maturation. To solve this problem, a genetic coefficient for the duration of tuber filling needs to be included in the model.

Survey of potato production and possible yield constraints in Argentina

SummaryThe potato is the most important horticultural crop in Argentina. Its commercial cultivation started in 1872/73 and production greatly increased due to area and yield increases. This paper surveys potato production in Argentina. It describes and quantifies distribution of crop area and production and the agro-ecological conditions in each growing area. Yield constraints are identified and a yield gap analysis was performed using the LINTUL-POTATO simulation model. Possibilities for further yield improvement are discussed. The survey established that important yield improvements were achieved in the country during the last 20 years, mainly due to the use of high quality seed, new cultivars, improved fertilizers and irrigation techniques, and better control of pests and diseases. However, the actual yield, at least for the regions studied, is still well below the attainable and potential yields established with the LINTUL-POTATO model. Suggestions are made to improve further the potato yield in the different growing areas.

Effects of foliar applied benzyladenine on grain yield and grain protein in wheat (Triticum aestivum L.)

The effects of foliar applications of nitrogen and benzyladenine (BA) on grain yield and grain protein of wheat grown under field conditions were studied over 2 years with 5 cultivars at 2 locations. Nitrogen (N) at 20 kg.ha−1, and BA at 100 or 800 mg.l−1 were applied alone or combined at pre and post-anthesis; applications of BA at 8 mg.l−1 were also made on individual ears in order to study the effect on cell number. Weekly determinations of the chlorophyll content of the flag leaf were conducted after anthesis to study leaf senescence. At harvest, yield, yield components and grain protein percentage were determined. N and BA applications delayed chlorophyll loss in the flag leaf, but modified neither yield nor yield components. Foliarly applied BA increased grain protein in four of the five cultivars tested. It is concluded that delay of the senescence induced by BA might allow more energy to be available for N uptake by the crop leading to an increase in grain protein.

Physiological Age Research during the Second Half of the Twentieth Century

As in other crops, yield and quality in the potato is determined by the genotype × environment interaction; limited by seed, crop, and storage management; and reduced by weeds, pests, and diseases. Within the limiting factors, seed tuber quality is crucial, both in low- and high-input crops. If poor seed tubers are used in low-input crops, only low yields can be expected. If poor seed tubers are used in high-input crops, the crops will not take proper advantage of other inputs, such as water, fertilizers, and pesticides applied. At present, physical aspects, such as shape and presence of wounds, seed tuber size, health, and physiological age, are the main components of seed quality, impacting seed vigour. Physiological age is defined as the physiological status of a seed tuber at any time, determined by genotype, chronological age, and environmental conditions from tuber initiation until new plant emergence. This minireview summarizes the physiological age assessment methods and the effects of crop and storage environment and management on physiological age and future crop performance. Possible tactics to reverse physiological age effects are also discussed. More research is still needed to develop a reliable and predictable indicator or index which can relate physiological age to yielding potential.

Analysis of a complex crop production system in interdependent agro-ecological zones: a methodological approach for potatoes in Argentina

This paper shows how a highly complex potato production system, like the Argentinian one, can be surveyed and analysed. A survey was complemented with the use of a Geographic Information System and a simulation model approach which improves the understanding of the possibilities for increasing future crop production by expanding the area cropped with potatoes and/or the yield. A yield gap analysis was also a useful and comprehensive tool to identify and rank yield defining, yield limiting and yield reducing factors for those agro-ecological zones where the potato is currently grown. With these procedures, the physiological age of seed tubers and virus diseases were identified as the most relevant factors limiting and reducing yield. Specific strategies can be developed to counteract their limiting and reducing effects upon seed quality and tuber yield. The approach of this work does not only apply for the specific situation of the potato crop in Argentina, but this framework could be successfully applied to other crops or production systems elsewhere.

Seed potato (Solanum tuberosum L.) yield and tuber number increase after foliar applications of cytokinins and gibberellic acid under field and glasshouse conditions

The purpose of these experiments is to determine the effects of foliar applications of benzylaminopurine (BAP) and gibberellic acid (GA) on tuber number production of seed potatoes. In field experiments conducted during 1989/90 cv. Mailén was used and BAP, 50 mg·l−1 was foliarly applied at (1) tuber initiation, 36 days after emergence (DAE); (2) 54 DAE; and, (3) 64 DAE. Under glasshouse conditions, in 1991/92 cv. Spunta was used and BAP 50 mg·l−1+GA 50 mg·l−1 were applied 30 and 37 days after planting/transplanting. In 1992 cv. Huinkul, Kennebec and Spunta were used and BAP 50 mg·l−1+GA 50 mg·l−1 and “Biozyme” (Techic SA), a commercial product with auxin (IAA, 32.2 mg·l−1), gibberellic acid (GA3, 32.2 mg·l−1) and cytokinins (zeatin, 83.2 mg·l−1) at 5 ml·l−1 were applied. In cv. Mailén, a higher tuber number in the seed fraction (<80 g) was found when BAP was applied at each of the three crop stages, while applications 54 and 62 DAE also increased tuber number in the 80–400 g fraction. As a result of BAP applications, tuber yield was also significantly increased. In the glasshouse experiments, cv. Spunta showed a significant increase in minituber production in 3 out of 4 cases, either if the mother plant came from in vitro generated plantlets or minitubers, or if GA + BAP or Biozyme was applied. It can be concluded that the use of these PGRs under both field and glasshouse conditions in cvs. Mailén and Spunta can result in increased tuber number in the seed fraction.

Survey of Tillandsia recurvata L.: preference, abundance and its significance for natural forests

Abstract The ball moss (Tillandsia recurvata L.) is an epiphytic weed that causes a deleterious effect upon its host when abundance is high. Because of its increasing abundance a survey was carried out in three different sites of the Province of Buenos Aires, Argentina, covering about 1000 ha and 457 trees from 114 species, belonging to 79 genera and 44 botanical families. A scale of abundance, from 0 (no epiphytes) to 4 (almost the whole host with epiphytes) was used to estimate the T. recurvata population. In the Riparian Forest of Punta Lara almost 100% of the surveyed trees have an abundance of 0 and 1; the average for all sites showed 58% of the individuals with an abundance of 1, 10% with an abundance of 2, 8% with 3 less than 8% with abundance 4. Although there was no significant correlation between the diameter of the hosts and abundance of the epiphyte, 90% of the trees with the greatest abundance had a diameter greater than 0.40 m. Three host types were defined according to the epiphyte average abundance and preference: Group I, high susceptibility; Group II, moderate susceptibility; Group III, epiphyte avoiders. Species with rough, deep and no exfoliating barks, with horizontally growing branches, and no exudating allelophatic compounds or latex, which favour T. recurvata anchorage, are potential members of Group I, while species with smooth, exfoliating and continuous bark, branches growing close to the main trunk, and exudating allelopathic compounds or latex are potential members of Group III or epiphyte avoiders. From this survey eight host species were seen to be heavily laden with T. recurvata, regardless of the growth habit of the host (evergreen or deciduous), representing different genera and botanical families. It is important to point out that individuals heavily laden with T. recurvata showed signs of decline. As commercial forests and plantings are carried out under conditions that promote rapid growth, natural forests are more susceptible to the invasion of this epiphyte; therefore some measures should be taken to preserve or recover them; for example, the successful chemical control proposed by our research group.

The potential for production of high quality seed potatoes in Tierra del Fuego Island, Argentina

SummaryIn Argentina, different areas are suitable for seed potato production: however, each has particular problems, mainly related to different pest and diseases. Tierra del Fuego Island is well isolated from traditional potato growing areas. Therefore, it was tested for its potential for seed production.The cultivars Achatt. Mailén INTA. Pampeana INTA and Spunta were grown in Río Grande, San Pablo and Ushuaia from 1991–1994. Nematode presence and aphid population dynamics were recorded. Average tuber yield ranged from 20.1–37.6 t ha−1. After three years PVY and PLRV remained low (0–1% for different cultivars and locations). Moreover, seed tubers obtained were physiologically young. Long days, early frosts and strong winds may limit tuber yield in some years. The island can be considered as an ecological “safe haven” and is very suitable to obtain healthy and physiologically adequate seed potatoes.