Effects of drip irrigation modes on growth and physiological characteristics of Arabica coffee under different N levels

The objective of this study was to obtain the water-saving and efficient production mode of Arabica coffee. The effects of three drip irrigation modes,conventional drip irrigation( CDI),alternate drip irrigation( ADI) and fixed drip irrigation( FDI) on growth,photosynthetic characteristics,biomass accumulation and irrigation water use efficiency of Arabica coffee were investigated under three nitrogen levels,high nitrogen( NH),middle nitrogen( NM) and low nitrogen( NL). The results show that there was a significant Logistic curve between the plant height,the stem diameter of Arabica coffee and growth days. Compared with CDI,ADI had no significant effects on leaf net photosynthetic rate,stomatal conductance,instantaneous water use efficiency and biomass accumulation above ground of Arabica coffee,while FDI decreased significantly,ADI and FDI increased irrigation water use efficiency by 50. 59% and 32. 85%,respectively. Compared with NH,with the reduction of N application rate,net photosynthetic rate,stomatal conductance,biomass accumulation above ground and irrigation water use efficiency decreased by 6. 81%-12. 30%,13. 70%-22. 69%,9. 61%-16. 67% and 9. 78%-15. 64%,respectively. Compared with CDINH,ADINHdecreased net photosynthesis rate and the stomatal conductance not significantly,other treatments decreased by 9. 16%-19. 22%,14. 49%-32. 91%,and decreased biomass accumulation above ground by 8. 26%-27. 34% except ADINH,and increased irrigation water use efficiency by 16. 46%-60. 95% except CDINMand CDINL. Therefore,alternate drip irrigation under high N level( ADINH) is the best water and nitrogen coupling mode of young Arabica coffee tree for water efficiency.

Effect of irrigation modes on the senescence of hybrid rice after heading

The pot experiment was designed to investigate therelationship between the senescence of hybrid riceand the irrigation mode and conducted during1984-1985.There were 30 pots for each treatmentand each pot contained 17.5 kg soil.Hybrid riceShanyou 6 was sown on 10 Jun ahd transplanted

Effect of Different Irrigation Patterns on Transportation and Allocation of Carbohydrate During Grain Filling of Rice

Using intersubspecific hybrid rice Xieyou 9308 and Liangyou Peijiu as the tested materials, the effects of differentirrigation patterns on transportation and allocation of carbohydrate during grain filling stage was observed by the designwith three level of soil water content in irrigated field. The results showed that in the conventional flooding and thealternate dry-watering cultivations, the exported rate of stored carbohydrate from stem and photophate from the leaves were60 and 90 % respectively. The exported rate of carbohydrate was decreased significantly (P<0.01) in the non-floodingcultivation. There was no significant difference between the conventional flooding and dry-wet alternation treatments interm of the exported rate of carbohydrate. The filling grains were the major sinks for carbohydrate storage during grainfilling stage. Grains received nearly 50% of stored carbohydrate from leaf sheath and 80% of photophate from leaves. Atthe nonflooding condition the absorbing rates of grains were significantly decreased by 10 % from leaf sheath and 20 %from leaves photophate. Water stress leaded much decrease in absorbing ability for inferior grains, which might be one ofthe main causes for low seed-settling rate in non-flooding cultivation.

Optimal chemigation duration model based on the crop and environment effects

Herbicides with drip irrigation(chemigation)could control the herbicides application accurately as the irrigation technology,and could reduce the harm to humans and the environment.However,the herbicide concentration is not consistent in the advancing process along the drip irrigation tape of different lengths,which not only influences the crop growth and results in herbicide residue.In this study,the crop and environmental effects of chemigation were discussed,potassium permanganate was used to replace herbicides,and a laboratory test was conducted to determine the best application duration.Based on this result,the maize field experiment of chemigation under plastic mulch was carried out to compare the effects of maize growth index,yield and herbicide residue for determining the optimal chemigation mode.The result shows that there is no significant difference in the application uniformity among treatments,but the leaf area index(LAI),yield,and double-ear rate of maize under continuous application(CA)were higher than those under periodic application(PA)and no application(NA)significantly.One month after the application,the acetochlor residue of the two modes was less than 1%,which would not cause pollution to the surrounding environment.And there was a significant linear regression relationship between the length of drip irrigation tape and the optimal application duration under the same acetochlor dosage.