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NEW MEXICO STATE UNIVERSITY (2016)

Water stress physiology and crop modeling of spring safflower under different irrigation management strategies

Sukhbir Singh

Titre : Water stress physiology and crop modeling of spring safflower under different irrigation management strategies

Auteur : Sukhbir Singh

Université de soutenance : NEW MEXICO STATE UNIVERSITY

Grade : Doctor of Philosophy (PhD) 2016

Résumé partiel
Increased pressure on irrigation water resources coupled with periodic drought in the Southern High Plains has increased the need for drought tolerant crops and irrigation management strategies in the region. Overall aim was to understand how a deep rooting desert originated crop like safflower fits in the Southern High Plains where irrigation is applied by spraying water frequently. We were also interested whether any management strategy like preseason irrigation improves its adaptability. The objectives of this study were to : (1) understand drought physiology and yield formation of spring safflower cultivars under different irrigation management practices, (2) study water extraction patterns of spring safflower under different irrigation management practices, (3) adapt the Decision Support System for Agrotechnology Transfer (DSSAT) Cropping System Model (CSM-CROPGRO) to simulate growth and seed yield of spring safflower. To achieve these objectives, two studies were conducted at Agricultural Science Center (ASC) of New Mexico State University, Clovis, NM. In the first study, drought physiology and yield formation of two diverse spring safflower cultivars were assessed under different irrigation levels with or without preseason irrigation. One half of the experimental blocks received preseason irrigation of 164 in 2012 and 153 mm in 2013 to refill the soil profile utilized by the previous crops, while the other half remained depleted. Five in-season irrigation levels (I1 to I5) ranging from 88 to 392 mm in 2012 and from 83 to 373 mm in 2013 were imposed on both preseason irrigation and no-preseason irrigation blocks. Higher leaf water potential (Ψ1) was observed under increased water availability either by preseason irrigation or by higher in-season irrigation level in safflower during two observation dates in both years. Osmotic potential at full turgor (Ψπ100), photosynthesis rate (P n) and transpiration rate (Tr) decreased with a reduction in Ψ1 under water stress conditions. The relative water content (RWC) was affected only by the in-season irrigation levels in both years. The preseason irrigation increased seed yield of safflower by 39 and 118% over no-preseason irrigation in 2012 and 2013, respectively. A gradual increase in seed yield was observed with an increase in irrigation levels ; and the highest irrigation level, Is increased seed yield by 85 and 171% over the lowest irrigation level, I1 in 2012 and 2013, respectively. Seed yield increased with increase in Pn, plant biomass, number of heads per plant, and number of seeds per head but not with 1000-seed weight under increased water availability. Overall, increased availability of water through preseason irrigation or through in-season irrigation levels improved safflower physiology and yield formation.

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Page publiée le 29 octobre 2016, mise à jour le 11 novembre 2018