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Recovery strategy of plant growth and yield following the foliar K and Ca applications on the salt-stressed rice plant

Takeshi Ikeda , Tomoko Tsutsumi and Yuuhei Chiba

Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan, Email tanuki@agr.niigata-u.ac.jp

Abstract

Salt damage occurs in dry or semi-dry areas around the world. One of the main causes is excessive sodium accumulation. A series of experiments was done to reduce salt damage for rice plants by applying foliar potassium or calcium solutions. More recovering of salt-stressed rice was found with potassium nitrate than calcium nitrate. Recovery levels were greater with 1 mM than with 5mM K. It is suggested that the high K/Na ratio improved rice growth recovery from salt damage and raised yield.

Media summary

Lessening salt damage on foliar potassium solution was explained with being high K/Na ratio to cause low sodium.

Key Words

Calcium solution, K/Na ratio, potassium solution, recovering from salt damage, salt-stressed rice.

Introduction

Recently it is often reported about salt damage to crop production at the irrigated lands and coastal areas in Asia. The main causes were high sodium accumulation in the plants. The following three experiments were conducted to reduce salt damages with ①applying calcium nitrate tetrahydrate and calcium hydrogen phosphate(2001), ②applying potassium nitrate and calcium nitrate tetrahydrates (2002), ③with applying the two level’s potassium nitrate(2003) in rice.

Material and Methods

Rice cv. Koshihikari (salt sensitivity ; medium) was grown in salty solution (100 & 200 mM NaCl) in this experiment (2001-2003). Nursering seedlings with seven leaves were transplanted in 1.2 liter pot (15.5cm φ x 19cm) compacted with loamy-sand soil. Experimental design is shown in Fig.1. Salt treatments were applied on vegetative (from 18 to 48 days from transplanting) and reproductive (from 63 to 83 days from it) stages. Three year’s experiments were carried out almost the same date. The three foliar applications of each solution were given every five days.

Fig. 1 Experimental design in three years (2001-2003)

Results

2001

Top dry weight on vegetative stage decreased in higher salt solutions (Fig.2). That in 100 mM salt solution increased with applying both calcium solutions. Sodium concentration increased in higher salt solutions, however that sprayed with calcium solutions tended to be decreased in 100 mM salt one (Fig.3). Grain yield per plant was not shown significant differences between the treatments (Table 1). The response in lessening of salt damage seemed to be different in anions ; more effective by nitrate tetrahydrate than by hydrogen phosphate.

Fig.2 Top dry weight per plant (2001). Vertical bars indicate

meanS.E.(n=6).

Fig.3 Na concentration in the plant (2001).

2002

Significant differences in dry weight were not observed between the treatments during and just after treatments, however were observed on potassium nitrate tetrahydrate after heading (Fig. 4). Sodium concentration in plants was low just after treatment and after heading. On the other hand, potassium concentration was relatively higher at the same periods (Fig.5, 6). Grain yield in potassium nitrate tetrahydrate was higher due to grain number per ear (Table 2). Its lessening effects on salt damage in dry weight and yield were more by potassium nitrate than by calcium nitrate tetrahydrates (Fig.2).

Fig.4 Top dry weight per plant (2002). Vertical bars indicate

indicate meanS.E.(n=6).

Fig.5 Na concentration in the plant (2002). Vertical bars indicate

indicate meanS.E.(n=3).

Fig.6 K concentration in the plant (2002). Vertical bars indicate

indicate meanS.E.(n=3).

2003

Top dry weight decreased with being high salt solutions (Fig.7). However it tended to be higher with foliar application of potassium in all treatments. Sodium concentration in plant decreased, whereas potassium one showed no clear differences between the treatments (Table 4). Recovery of grain yield was shown to potassium spray (1 mM>5mM K) on the plants (Table 3). K/Na ratio was high by treating with potassium nitrate tetrahydrate due to prevent sodium absorption (Table 4).

 

Fig.7 Top dry weight per plant (2003). Vertical bars indicate

meanS.E.(n=6).

Its effect on rice was more observed in vegetative stage than in reproductive one.

Conclusion

It was suggested to need keeping on high K/Na ratio to introduce low sodium content on early plant stage for hastening the recovery of salt damage and then increasing dry weight and grain yield.

References

Sultana N, Ikeda T and Itoh R (1999). Effect of NaCl salinity on photosynthesis and dry matter accumulation in developing rice grains. Environmental and Experimental Botany 42, 211-220.

Sultana N, Ikeda T and Kashem MA (2001). Effect of foliar spray of nutrient Solutions on photosynthesis, dry matter accumulation and yield in seawater-stressed rice. Environmental and Experimental Botany 46, 129-140.

Sultana N, Ikeda T and Kashem MA (2002) Effect of seawater on photosynthesis and dry matter accumulation in developing grains. Photosynthetica 40, 115-119.

Sultana N, Ikeda T and Kashem MA (2000) Amelioration of NaCl stress by Gibberellic acid in wheat seedling. Bulletin of the Faculty of Agriculture Niigata University 52, 71-77.

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