Willow (Salix sp.) sawdust (WS) is used as a component of growing media in horticultural crops and potted plant production in Santa Fe, Argentina. We evaluated the use of the germination bioassay as an indicator of WS maturity/phytotoxicity by comparing bioassays results with dry matter production of plants growing in the same substrate. Lettuce (Lactuca sativa L.) seeds were sown on filter paper moistened with extracts of WS composted for different times. Germinated seeds were counted (G) and the radicle growth (L) measured. Germination index (Gi) = G/G 0 × L/L 0 × 100, where G 0 and L 0 are values obtained using distilled water (control). The global germination index (GI) was the Gi average of the 50 and 75% extract dilution. GI of lettuce increased from 5% in the noncomposted WS to 93.3% in the WS composted for 40 days. GI did not change significantly after 40 days of composting. Calendula dry matter production increased from 8 g/plant in non-composted WS to 17.1 g/plant in WS composted for 40 or 60 days. The addition of nitrogen and pH corrector did not affect GI of the WS growth media but they both increased calendula dry matter production to 21.1-22.7 g/plant when WS composted for 40 or 60 days was used as a growth medium.

In Santa Fe, the central-east area of Argentina, the expansion of fruit tree crops requires the introduction and evaluation of low chilling varieties. The aims of this study was to characterize the phenological behaviour and the reproductive traits of peach (Prunus persica L. Batsch) and nectarine varieties with chilling requirements ranging from 150 to 650 chilling hours (CH). Low chilling varieties (≤ 450 CH) had higher flower density (22.0-56.5 flowers m -1 ), fruit set (26.0-56.7%), fruit yield (9.3-36.6 kg per plant), and low coefficient of fruit yield variability than varieties with a higher chilling requirement (>500 CH). The phenology of high chilling requirement varieties had the advantage that blooming and fruit set happened after the period of late frost occurrence. However, they did not satisfy their chilling requirement, showing an inadequate vegetative and reproductive behaviour. Low chilling varieties began to sprout during July, and the period of full bloom occurred from July 14 th to August 4 th . Fruit harvest was initiated on October 19 th with the cv. 'Flordastar' and it extended for 58 days. However, on low chilling varieties the harvest time was reduced in ten days. Flower density, fruit set and fruit yield showed a negative relationship with the chilling requirement of the variety.

In Santa Fe, Argentina, strawberries (Fragari ×ananassa Duch.) are cultivated in the area of Coronda where N fertilization usually exceeds crop requirements. The objective of this work was to test four types of fertilization methodology to optimize fertilizer use efficiency. Experiments were carried out at the horticultural center of the Facultad de Agronomía y Veterinaria, in Esperanza, Santa Fe, 31.15° S latitude, on a typical argiudol soil. `Chandler' was planted 13 Mar. 1996. Nitrogen demand was related to the dry matter production with N content decreasing to increment of biomass (W), soil N mineralization was estimated according to the program EDAFO version 3. Using previous data, a monthly balance was calculated and four treatments were devised: control (T0) = without fertilization; treatment 1 (T1) = N fertilization covering the accumulated monthly deficit, 53 kg·ha-1 (47 lb/acre); treatment 2 (T2) = N fertilization covering the monthly deficit 66 kg·ha-1 (58 lb/acre); treatment 3 (T3) = N fertilization covering the total crop demand 117 kg·ha-1 (104 lb/acre). All N treatments significantly increased yields over the control. Yield increased to increasing N rates from 0 to 53 kg·ha-1. This response was due to an increase in fruit number but not in fruit weight. High N rates promoted runner growth without increasing fruit yield. The use N balance method for strawberry fertilization showed satisfactory results. Accumulated N balance (T1), required the least amount of N fertilizer while producing good yield, thus it should be the method adopted to reduce costs and environmental risks of N fertilization.

Growth of 'Fiesta Gitana' calendula (Calendula officinalis) in growth medium prepared from 75% (vol.) composted willow (Salix sp.) sawdust (WS), with or without additional nitrogen (N) (4% w/w) during composting, and 25% (vol.) perlite was examined. Total plant dry matter, dry matter partition to flowers, and plant height at 77 days after planting were similar in media containing composted WS to values in achieved in a sphagnum peat:perlite (75:25, vol.) control medium. Relative to these media, non-composted WS:perlite (75:25, vol.) resulted in average reductions of total dry matter (57%), dry matter partition to flowers (50%), plant height (43%), flower diameter (73%), and flower buds per plant (82%). In a further study, increasing the proportion of N-enriched composted WS in perlite from 25% to 75% did not affect total dry matter, plant height, or flower number per plant of 'Fiesta Gitana' calendula or 'Perfection Gold' marigold (Tagetes erecta) compared to values achieved in the sphagnum peat:perlite (75:25, vol.) control medium. Since flower diameter decreased in both species when the N-enriched composted WS exceeded 50%, we suggest that this "waste" product can substitute for all the sphagnum peat, but should not exceed 50% volume in a perlite mixture.

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