Abstract
The research was conducted to detect changes in growth, physiology and nutrient concentration in response to two watering regimes (well-watered and water-stress conditions) and to two nutrient regimes (with or without fertilization) of oil palm. Under stress conditions, changes in plant growth, dry matter allocation, relative water content, leaf relative conductivity, leaf N, P and K concentration are usually observed. These characteristics and related parameters were determined and the experiment results are listed as follows: (1) fertilization promoted the growth of oil palm under well-watered conditions, while under water stress conditions its effects on growth was negative. The ratio of root/shoot was increased under water stress condition; (2) relative water content and chlorophyll a/b content were gradually decreased while leaf relative conductivity was increased quickly under water and nutrient stress conditions during the experiment. It is obvious that water stress had a greater influence than nutrient stress on these parameters; (3) water and nutrient stress decreased leaf nitrogen and phosphorus concentration but increased potassium concentration; the combination of water and nutrient stress made significant effects on nitrogen and phosphorus concentration, but no significant effects on potassium concentration. Moreover, deficiency of both water and nutrients in combination had the greatest impact on changes in these traits of oil palm. Key words: Plant growth, physiology response, nutrient concentration, water stress, nutrient stress.
Highlights
Water and nutrient deficiency are major factors limiting the productivity and geographical distribution of many species, including important agricultural crops (Conner et al, 1998; Zhang et al, 2007; Tseira and Irit, 2009; Andrews et al, 2010)
We examined the variance of plant growth, dry matter allocation, relative water content, leaf relative conductivity, chlorophyll a/b, changes of leaf total N and P concentration were determined
After about 3 months of continuous growth, the dry matter accumulation and allocation were significantly affected by water and nutrient stress (Table 1)
Summary
Water and nutrient deficiency are major factors limiting the productivity and geographical distribution of many species, including important agricultural crops (Conner et al, 1998; Zhang et al, 2007; Tseira and Irit, 2009; Andrews et al, 2010). Fertilization is most effective when trees are not water-stressed, and irrigation is most effecttive when nutrients are not scarce (Sands and Mulligan, 1990). Understanding the mechanisms of plant tolerance to water and nutrient stress is a crucial environmental research topic (Wang et al, 2009a). Exposure to water or nutrient stresses triggers many common reactions in plants that lead to a decrease in the growth rate and relative water content; change of the biomass partition and nutrient distribution. Another consequence of exposure to these stresses is the increase in root/shoot ratios and leaf relative conductivity. Numerous studies have shown that plants will respond to a large set of parallel changes in growth, and in morphological and physiological responses when the plants are exposed to water or nutrient stress environment (Chapin, 1991)
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