Hydraulic properties and drought response of a tropical bamboo (Cephalostachyum pergracile)

Bamboo plants are an essential component of tropical ecosystems,yet their vulnerability to climate extremes,such as drought,is poorly understood due to limited knowledge of their hydraulic properties.Cephalostachyum pergracile,a commonly used tropical bamboo species,exhibited a substantially higher mortality rate than other co-occurring bamboos during a severe drought event in 2019,but the underlying mechanisms remain unclear.This study investigated the leaf and stem hydraulic traits related to drought responses,including leaf-stem embolism resistance(P50leaf;P50stem) estimated using optical and X-ray microtomography methods,leaf pressure-volume and water-releasing curves.Additionally,we investigated the seasonal water potentials,native embolism level(PLC) and xylem water source using stable isotope.We found that C.pergracile exhibited strong resistance to embolism,showing low P50leaf,P50stem,and turgor loss point,despite its rapid leaf water loss.Interestingly,its leaves displayed greater resistance to embolism than its stem,suggesting a lack of effective hydraulic vulnerability segmentation(HVS) to protect the stem from excessive xylem tension.During the dry season,approximately 49% of the water was absorbed from the upper 20-cm-deep soil layer.Consequently,significant diurnal variation in leaf water potentials and an increase in midday PLC from 5.87±2.33% in the wet season to 12.87±4.09%in the dry season were observed.In summary,this study demonstrated that the rapid leaf water loss,high reliance on surface water,and a lack of effective HVS in C.pergracile accelerated water depletion and increased xylem embolism even in the typical dry season,which may explain its high mortality rate during extreme drought events in 2019.

General anesthesia versus local anesthesia for penetrating keratoplasty: a prospective study

AIM:To examine which anesthesia general or local is more effective for penetrating keratoplasty(PKP).METHODS:Patients with indications for PKP(n=141)were enrolled in a prospective study and randomly divided into general anesthesia group(group A,70 eyes)and local anesthesia group(group B,71 eyes).Patients received optical PKP(group A1,30 eyes;group B1,30eyes)or therapeutic PKP(group A2,40 eyes;group B2,41 eyes).Measurement of anterior chamber treatment time(T)for PKP patients and the ratio(R)of the area of the pupils to that of recipient graft region.T and R values,as well as perioperative and postoperative complications,were compared between groups A and B using t-test orχ2test.RESULTS:Patients were followed for 2wk after PKP.T was(13.45±8.64)min for group A and(7.36±5.24)min for group B,a statistically significant difference(P【0.001).The R value for group A was stable during the operation,while for PKP patients in group B the value initially increased then gradually decreased to normal after suturing.In group B,extrusion of intraocular contents occurred in 5 eyes,and iridal prolapse occured in 11cases;no perioperative complications occurred in group A.Relapse rate for fungal keratitis was 13.04%in group B and 0%in group A.CONCLUSION:Under general anesthesia,pupils remaine stable during PKP and perioperative complications are averted.General anesthesia gives more time to treat pathological changes in the anterior chamber and treatment success rate is higher.