Control efficacy of Ca-containing foliar fertilizers on bitter pit in bagged 'Fuji' apple and effects on the Ca and N contents of apple fruits and leaves.

BACKGROUND: The preharvest application of Ca-containing foliar fertilizers can reduce the incidence of bitter pit (BP) in apples and improve fruit quality by increasing the Ca content and decreasing both the N content and the N/Ca ratio in fruits. In this study, we aimed to investigate the control efficacy of Ca-containing fertilizers on the incidence of BP and their effects on the Ca and N contents in bagged 'Fuji' apples by spraying foliar fertilizer containing calcium chloride (CaCl2 ), calcium nitrate [Ca(NO3 )2 ] or calcium formate [Ca(HCOO)2 ] at an early stage, five days after full bloom (DAFB) and 40 DAFB, and at a late stage, 80 DAFB and 125 DAFB. RESULTS: The incidences of BP were reduced significantly by 43.2-73.0%, and the efficacy of spraying at an early stage was significantly higher than that of spraying at a late stage. The Ca content of bagged apple fruits increased whereas the N content and N/Ca ratio decreased after spraying Ca-containing foliar fertilizers; however, the Ca content, N content and N/Ca ratio of apple leaves were differentially influenced. CONCLUSION: Foliar fertilizer containing CaCl2, Ca(NO3 )2 or Ca(HCOO)2 can be used at an early stage to control BP in apple and improve the quality of bagged apple fruits. © 2018 Society of Chemical Industry.

[Response of water status indicators in apple saplings to drought stress under shelter from rain.] / é¿é›¨çŽ¯å¢ƒä¸‹è‹¹æžœå¹¼æ ‘æ°´åˆ†çŠ¶æ€æŒ‡æ ‡å¯¹å¹²æ—±èƒè¿«çš„å“åº”.

The main tree water status indicators which sensitively responded to drought stress and related to tree water balance were investigated in treatment of progressive decrease of soil water potential under shelter from rain. The results showed that stem maximum daily shrinkage (MDS) and midday stem water potential (Ψstem) were most sensitive to drought stress among all the water status indicators. MDS not only significantly responded to reference crop evapotranspiration (ET0), but also was sensitive to soil drought stress. MDS was significantly positively related to ET0, and the correlation between relative stem daily maximum shrinkage (MDSr) and relative soil water potential (Ψr soil) was highly significant. Moreover, the stems could be measured in succession and recorded automatically. Midday Ψstem was also sensitive to soil drought stress, and significantly negatively related to ET0. The correlation between relative midday stem potential (Ψr stem) and Ψr soil was significant. But so far, it is difficult to automatically measure either leaf or stem water potential. Predawn leaf water potential (Ψpd), daily stem growth (DG) or stomatal conductance (gs) also responded to drought stress to some extent under moderate or heavy drought stress, but they were not sensitive.