Performance of coffee seedlings as affected by soil moisture and nitrogen application

Transcription

1 Performance of coffee seedlings as affected by soil moisture and nitrogen application Alveiro Salamanca-Jimenez Willliam R. Horwath SSSA Ecosystem Service Conference March 8th, 214 Sacramento, CA

2 Coffee World: Second most valuable commodity Involves ~ 5M people A family business (Da Matta et al, 27) Brazil, Taiwan, Indonesia Colombia: larger producers 56K families Farms <15 Acs (ICO, 213; Federacafe, 213)

3 Dry bean (kg ha -1 ) N requirements depend on growth stage Germinative Seedling Vegetative growth Productive 9 Coffee yield Colombia Caturra Colombia Caturra Colombia Bag 13x17cm Bag 17x23cm Pot 6x12cm Treatments Early growth is the most critical stage (Salazar, 1996)

4 Economic and environmental impact For the vegetative stage losses reach up to 4% (Leal et al, 21) NO 3- -N losses by leaching >33% was leached below 12cm (Cannavo et al, 213) Soil water CRITICAL NUE < 3% NUE vs WUE?

5 Based on these considerations: It is imperative to study the nutritional requirements of coffee seedlings to ensure maximum yield potential of reproductive coffee trees. We aim to generate knowledge about seedlings response in terms of growth, WUE and NUE to different soil water levels and N rates under greenhouse conditions. The main goal is maximizing early growth and potential yield by improving resources use efficiency to maintain ecosystem services in fragile mountain ecosystems in Colombia.

6 OM ph Olsen P K Ca Mg CEC Soil % water KCl ppm cmol + kg Andisol Three months old plants Watered every 3 days Materials and methods Number Design: A randomized block with a 4x4 factorial and 1 replications Treatments Soil m (bars) VWC (%) N doses (g N plant -1 ) (5) (39) (33) (23) Urea 15 N (1 atom %)

7 Measurements After 9 months Dry weight of leaves, stems and roots Last 3 months WUE WUE = dry biomass / water applied Leaf 13 C composition (δ) N content Leaf 15 N δ lsr = (R std - R lsr )/(R std ) x 1 Photosynthesis Stomatal conductance Nddf l = (δ 15 N l - δ 15 N air )/(δ 15 N fert - δ 15 N air ) x 1 NUE Transpiration N Recovered = (Nddf l x N l )/(N applied )

8 Transpiration ( ) Physiological response Conductance (mol H 2 O / m 2 s) Transpiration (mmol H 2 O / m 2 s) Water effect (p= <.1) N effect (p= <.1) No interaction (p=.3569) Water effect (p= <.1) N effect (p= <.1) No interaction (p=.236)

9 Shoot biomass (g) R : S ratio Pant growth Shoot biomass (g) R:S ratio (g/g) Water effect (p= <.1) N effect (p= <.1) Interaction (p= <.1) Water effect (p=.312) N effect (p= <.1) Interaction (p=.65)

10 WUE (g shoot / L water) δ 13 C Water Use Efficiency WUE (g biomass / L water) Leaf 13 C ( / ) Water effect (p=.243) N effect (p= <.1) Interaction (p=.79) Water effect (p= <.1) N effect (p= <.1) Interaction (p=.179)

11 Leaf N (mg plant -1 ) N recovered from urea (%) N Use Efficiency Leaf N [ ] (mg / g of leaf) Leaf N recovery (%) Water effect (p= <.1) N effect (p= <.1) Interaction (p=.175) Water effect (p=.3) N effect (p= <.1) Interaction (p=.385)

12 Final considerations The water*n interaction did not affect physiological response in terms of conductance and transpiration. Both decreased as water decreased and N increased. Shoot growth decreased by decreasing soil water but increased when N increased. Root growth exhibited the opposite behavior. WUE increased by increasing N in a greater proportion than by decreasing water By increasing N application leaf N contents increased but NUE decreased. Both were less affected by soil water content.

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