Light-harvesting regulation from leaf to molecule with the emphasis on rapid changes in antenna size.

In the sunlight-fluctuating environment, plants often encounter both light-deficiency and light-excess cases. Therefore, regulation of light harvesting is absolutely essential for photosynthesis in order to maximize light utilization at low light and avoid photodamage of the photosynthetic apparatus at high light. Plants have developed a series of strategies of light-harvesting regulation during evolution. These strategies include rapid responses such as leaf movement and chloroplast movement, state transitions, and reversible dissociation of some light-harvesting complex of the photosystem II (LHCIIs) from PSII core complexes, and slow acclimation strategies such as changes in the protein abundance of light-harvesting antenna and modifications of leaf morphology, structure, and compositions. This review discusses successively these strategies and focuses on the rapid change in antenna size, namely reversible dissociation of some peripheral light-harvesting antennas (LHCIIs) from PSII core complex. It is involved in protective role and species dependence of the dissociation, differences between the dissociation and state transitions, relationship between the dissociation and thylakoid protein phosphorylation, and possible mechanism for thermal dissipation by the dissociated LHCIIs.

Continuous interscalene block in patients having outpatient rotator cuff repair surgery: a prospective randomized trial.

BACKGROUND: We performed this randomized trial to compare the recovery profile of patients receiving single injection (SISB) and continuous interscalene brachial plexus block (CISB) or general anesthesia (GA) for arthroscopic rotator cuff repair surgery through the first postoperative week. Our primary hypothesis was that the highest pain numeric rating scale (NRS) (worst pain score) at the end of the study week would be lower for patients in the CISB group than for patients in the SISB or GA groups. METHODS: Seventy-one patients scheduled for elective outpatient arthroscopic rotator cuff repair were enrolled. CISB patients received 20 mL of 0.5% ropivacaine as a bolus through a catheter, whereas SISB patients received the same injection volume through a needle. CISB patients received an infusion of 0.2% ropivacaine at 5 mL/h with a patient-controlled bolus of 5 mL hourly for 48 hours. GA-only patients received a standardized general anesthetic. Postoperative highest NRS pain scores through the first postoperative week, time-to-first pain, analgesic consumption, fast-tracked postoperative anesthesia care unit (PACU) bypass rate, length of PACU stay, time-to-discharge home, total hours of sleep, and related adverse effects were recorded in the PACU and at home on postoperative days 1, 2, 3, and 7. RESULTS: No patient in the CISB or SISB groups reported a NRS ≥1 or required analgesics while in the PACU. While most patients in the CISB and SISB groups were fast-tracked to PACU discharge, no patient in the GA group was fast-tracked (Χ P = 0.003). Length of stay in the PACU was significantly shorter for the CISB and SISB groups than for the GA group (20 ± 31, 30 ± 42, and 165 ± 118 minutes, respectively (CISB vs GA, P < 0.001; SISB vs GA, P <0.001), and time-to-discharge home was significantly shorter when compared with the GA group. Time to first pain report was longer in the CISB group. Mean NRS scores were lower for patients in the CISB group than in the SISB and GA groups on postoperative days 1 and 2, and use of narcotics (doses ≥1) was lower until postoperative day 3. Patients who received CISB slept significantly longer than patients who received SISB or GA (P < 0.01) during the first 48 hours postoperatively. By the end of the study week, 26% of patients in the CISB group, 83% in the SISB group, and 58% of GA patients reported NRS ≥4 (both P-values ≤ 0.05). CONCLUSION: The analgesic benefits of CISB found in the PACU and immediately after discharge extend through the intermediate recovery period ending on postoperative day 7.

The effects of ultrasound-guided adductor canal block versus femoral nerve block on quadriceps strength and fall risk: a blinded, randomized trial of volunteers.

BACKGROUND AND OBJECTIVES: Adductor canal block (ACB) has been suggested as an analgesic alternative to femoral nerve block (FNB) for procedures on the knee, but its effect on quadriceps motor function is unclear. We performed a randomized, blinded study to compare quadriceps strength following adductor canal versus FNB in volunteers. Our hypothesis was that quadriceps strength would be preserved following ACB, but not FNB. Secondary outcomes included relative preservation of hip adduction and degree of balance impairment. METHODS: The ACB was performed in one leg and the FNB in the contralateral leg in 16 volunteers using a randomized block sequence. For all blocks, 15 mL of 3% chloroprocaine was injected under ultrasonographic guidance. Maximal voluntary isometric contraction of knee extension and hip adduction was measured at baseline and at 30 and 60 minutes after block. After 60-minute assessments were complete, the second block was placed. A test of balance (Berg Balance Scale) was performed 30 minutes after the first block only. RESULTS: Quadriceps strength and balance scores were similar to baseline following ACB. Following FNB, there was a significant reduction in quadriceps strength (95.1% ± 17.1% vs 11.1% ± 14.0%; P < 0.0001) and balance scores (56 ± 0 vs 37 ± 17.2; P = 0.02) compared with baseline. There was no difference in hip adductor strength (97.0% ± 10.8% vs 91.8% ± 9.6%; P = 0.17). CONCLUSIONS: Compared with FNB, ACB results in significant quadriceps motor sparing and significantly preserved balance.

Fascia lliaca block for analgesia after hip arthroplasty: a randomized double-blind, placebo-controlled trial.

BACKGROUND AND OBJECTIVES: Fascia iliaca block (FIB) is often used to treat pain after total hip arthroplasty (THA), despite a lack of randomized trials to evaluate its efficacy for this indication. The objective of this study was to assess the analgesic benefit of FIB after THA. Our primary hypothesis was administration of FIB decreases the intensity of postoperative pain (numeric rating scale [NRS-11] score) compared with sham block (SB) in patients after THA. METHODS: After institutional review board approval and informed consent, 32 eligible patients having THA were recruited. In the postoperative care unit, although all patients received intravenous morphine sulfate patient-controlled analgesia, patients reporting pain of 3 or greater on the NRS-11 scale were randomized to receive ultrasound-guided fascia iliaca (30 mL 0.5% ropivacaine) or SB (30 mL 0.9% NaCl) using identical technique, below fascia iliaca. The primary outcome was pain intensity (NRS-11) after FIB. RESULTS: Thirty-two patients (16 in each group) completed the study; all patients received an FIB. There was no difference in pain intensity (NRS-11 = 5.0 ± 0.6 vs 4.7 ± 0.6, respectively) after FIB versus SB or in opioid consumption (8.97 ± 1.6 vs 5.7 ± 1.6 mg morphine, respectively) between the groups at 1 hour. The morphine consumption after 24 hours was similar in both groups (49.0 ± 29.9 vs 50.4 ± 34.5 mg, P = 0.88, respectively). CONCLUSIONS: The evidence in these data suggests that the difference in average pain intensity after FIB versus SB was not significant (95% confidence interval, -2.2-1.4 NRS units).

Effective volume of ropivacaine 0.75% through a catheter required for interscalene brachial plexus blockade.

BACKGROUND: Ultrasound guidance during peripheral nerve blocks has allowed for reduction in dose and volume of local anesthetic required to accomplish successful blockade using multiple injections through a needle. The authors undertook this study to determine the minimal effective volume required to accomplish successful interscalene brachial plexus block (ISB) through the catheter. METHODS: After obtaining institutional ethics committee approval and written informed consent, patients aged 18-75 yr and scheduled for arthroscopic shoulder surgery under ISB were enrolled. All patients using a step-up/step-down method and the starting dose of 15 ml of 0.75% ropivacaine received an ultrasound-guided ISB catheter. The injection volume was increased or decreased by 1 ml in case of block failure or block success, respectively. RESULTS: The authors found that the proportion of patients with successful blockade increased sharply from approximately 57% at 6 ml to 100% by 7 ml, indicating that a small increase in volume of ropivacaine 0.75% markedly affects the success rate. A total of 12 ISB with injection volume less than 7 ml resulted in successful anesthesia within 30 min, yielding an ED95 of 7 ml (95% CI 6.8-7.2) ropivacaine 0.75%. For the group as a whole, the median (min-max) sensory block onset time was 5 (5-20) min, the median (min-max) motor blocks for the biceps and the deltoid muscles were 7.5 (5-15) min and 10 (5-15) min, respectively. The median (min-max) block duration was 8.9 (3-15) h. CONCLUSIONS: An injection of a minimum of 7 ml of ropivacaine 0.75% through the catheter is required for success rate and timely onset of surgical anesthesia with ISB.

The sequence of administration of 1.5% mepivacaine and 0.5% bupivacaine does not affect latency of block onset or duration of analgesia in ultrasound-guided interscalene block.

BACKGROUND: During peripheral nerve blockade, different local anesthetics may be sequentially administered. Typically, a short- or intermediate-acting local anesthetic is administered before a long-acting local anesthetic to achieve a block with rapid onset and long duration. However, there is a paucity of data on advantages of such sequencing. We hypothesized that when using a sequential mixture of mepivacaine and bupivacaine for ultrasound-guided interscalene block, the order of injection of the drugs does not influence the clinical characteristics of the block achieved. METHODS: Sixty-four patients undergoing arthroscopic shoulder surgery (aged 18-65 years; ASA physical status I-II) with a single-injection ultrasound-guided interscalene brachial plexus block as sole anesthetic were studied. The subjects were randomized to receive 1 of 2 local anesthetic sequences: 15 mL of mepivacaine 1.5% followed by 15 mL of bupivacaine 0.5% (group A), or the same local anesthetics in the reverse order (group B). The durations of sensory and motor block were the primary outcomes. Block onset was also assessed. RESULTS: Duration of motor block was similar between group A and group B (10.1 ± 4.7 hours vs 10.3 ± 5.1 hours, mean difference 0.2 hours, 95% confidence interval [CI] -3.3 to 2.9, P = 0.9). Duration of analgesia was also similar between group A and group B (9.5 ± 5.6 hours vs 10.2 ± 4.5 hours, mean difference 0.7 hours, 95% CI -3.2 to 1.9, P = 0.42). Onset of sensory block was similar between the 2 groups (15.9 ± 7.1 minutes for group A, 13.9 ± 7.0 minutes for group B, mean difference 1.9 minutes, 95% CI -1.4 to 5.2, P = 0.25). CONCLUSIONS: The sequence in which 15 mL mepivacaine 1.5% and 15 mL bupivacaine 0.5% are administered does not seem to have a clinically meaningful effect on duration or onset of ultrasound-guided interscalene brachial plexus block.

The effect of stimulating versus conventional perineural catheters on postoperative analgesia following ultrasound-guided femoral nerve localization.

STUDY OBJECTIVE: To test the hypothesis that, if the femoral nerve is correctly localized using ultrasound (US) guidance, the type of perineural catheter used has no effect on catheter success. DESIGN: Randomized controlled trial. SETTING: Post-anesthesia care unit of an academic teaching hospital. PATIENTS: 40 ASA physical status 1, 2, and 3 patients, ages 55-85 years, undergoing elective total knee arthroplasty. INTERVENTIONS: All patients received postoperative continuous femoral nerve blocks and a single injection sciatic nerve block. Nerve localization was accomplished using US guidance and electrical nerve stimulation so that the needle tip was visualized deep to the femoral nerve. Patients were randomized to receive either stimulating (Group SC) or nonstimulating catheters (Group NSC) in the usual manner for each device. Catheters were bolused with ropivacaine and an infusion commenced. MEASUREMENTS: The primary outcome was quality of analgesia (as measured by a numerical rating scale). Other outcomes included sensory block success rate, number of attempts and time required to localize the needle tip correctly, number of attempts and time required to place the perineural catheter, amount of local anesthetic and opioid use postoperatively, and degree of completion of preset postoperative rehabilitation goals. MAIN RESULTS: Quality of analgesia was similar at all time intervals. Rates of successful femoral block (95% vs 80%; P = 0.34) were similar between groups. Time required to position the catheter was greater in Group SC than Group NSC (3.45 ± 2.05 min vs 1.72 ± 0.88 min; P < 0.01). CONCLUSIONS: Ultrasound guidance for needle localization prior to catheter insertion for femoral nerve block results in similar block characteristics between stimulating and nonstimulating catheters. The use of nonstimulating catheters avoids the technical challenges of stimulating catheters and does not require additional helpers.

The minimum effective anesthetic volume of 0.75% ropivacaine in ultrasound-guided interscalene brachial plexus block.

BACKGROUND: The use of ultrasound to monitor needle placement and spread of local anesthetics (LA) has allowed reductions in the volume of LA required to anesthetize peripheral nerves. In the current study we investigated the minimal volume necessary to accomplish surgical anesthesia with interscalene brachial plexus block. METHODS: Twenty ASA physical status I-III patients, ages 18 to 75 years and scheduled for shoulder surgery under interscalene brachial plexus block, were enrolled. Using a previously validated step-up/step-down method, we determined the injection volume of 0.75% ropivacaine used for consecutive patients by the outcome of the preceding block. The starting volume was 15 mL (3 injections of 5 mL per each trunk); in the case of block failure, the volume was increased by 1 mL, whereas after successful block, the volume was reduced by 1 mL. The study was stopped upon achieving the secondary stopping rule of 10 consecutive successful interscalane blocks using 5 mL of ropivacaine 0.75%. Successful surgical anesthesia with the brachial plexus block was defined as presence of adequate motor block (motor score of ≤2 on 0 to 4 scale), absent sensation to cold and pinprick sensation within 30 minutes of injection, and absence of the need for general anesthesia for completion of surgery. Duration of sensory blockade was assessed by asking the patient to record the time of first pain sensation. RESULTS: Under our study conditions, successful surgical anesthesia for arthroscopic shoulder surgery can be achieved with 5 mL of 0.75% ropivacaine, or approximately 1.7 mL per each of the 3 trunks of the brachial plexus (superior, middle, and inferior). The study was stopped after 10 consecutive successful blocks with 5 mL of LA (100%, 95% confidence interval [CI]: 74.1%-100%). For the group as a whole, the median (range) sensory block onset time was 5 (5-20) minutes, the median (range) motor block for the biceps was 7.5 (5-15) minutes, and for abduction 10 (5-15) minutes. The median (range) block duration was 9.9 (5-19) hours, and the mean (SD) block performance time was 8.0 ± 3.2 minutes. Mean duration of analgesia was 9.9 ± 3.7 hours. Duration of analgesia was not associated with volume of LA (r = 0.05, P = 0.83). CONCLUSIONS: All patients in our study had successful surgical blocks with 5 mL of LA. However, the lower limit of the CI (calculated on the assumption of a single failure) does include the possibility of a 25% failure rate; thus studies using similar stopping rules for doses higher than 5 mL are nonetheless warranted.

A new tool measuring oral malodor quality of life.

A valid measure of oral malodor (halitosis) and associated quality of life is required for the complete assessment of treatment effectiveness. The purpose of this study was to analyze the psychometric and clinimetric validity of the Halitosis Associated Life-quality Test (HALT) questionnaire, a specific 20-item quality-of-life measure for halitosis. The HALT is a de novo designed tool based on patient interviews and literature review. The University Hospital was the setting for the prospective random non-controlled study design. The comparison between the evaluator' scales on organoleptic testing and HALT scores was performed during the patient's initial visit. HALT was completed by 33 and 16 patients at the initial visit and at 3 months after treatment commencement, respectively. Two treatment arms comprising an experimental arm including Caphosol rinse for xerostomia-associated halitosis, and an established treatment arm with laser cryptolysis were compared. Cronbach's α was 0.93; coefficient alpha with deleted variables was between 0.92 and 0.94; equal length Spearman-Brown coefficient is 0.95. The Cronbach's alphas of each split questionnaire were 0.85 and 0.88, respectively, and test-retest scores were highly correlated (r = 0.85). HALT scores were significantly associated with the scales of organoleptic test (F = 118, p < 0.001; r = 0.96, p < 0.001). HALT successfully measured each treatment arm and showed improvement (p < 0.002) in both arms. Although cryptolysis was more efficacious, the encouraging results of the Caphosol arm indicate that additional investigation is warranted. HALT proved a valid outcome measure for patients with halitosis, describes its burden and is sensitive to clinical change.

The effect of mixing 1.5% mepivacaine and 0.5% bupivacaine on duration of analgesia and latency of block onset in ultrasound-guided interscalene block.

BACKGROUND: Short- and long-acting local anesthetics are commonly mixed to achieve nerve blocks with short onset and long duration. However, there is a paucity of data on advantages of such mixtures. We hypothesized that a mixture of mepivacaine and bupivacaine results in a faster onset than does bupivacaine and in a longer duration of blockade than does mepivacaine. METHODS: Sixty-four patients undergoing arthroscopic shoulder surgery (ages 18 to 65 years; ASA physical status I-II) with ultrasound-guided interscalene brachial plexus block as the sole anesthetic were studied. The subjects were randomized to receive 1 of 3 study solutions: 30 mL of mepivacaine 1.5%, 30 mL of bupivacaine 0.5%, or a mixture of 15 mL each of bupivacaine 0.5% and mepivacaine 1.5%. The block onset time and duration of motor and sensory block were assessed. RESULTS: Onset of sensory block in the axillary nerve distribution (superior trunk) was similar among the 3 groups (8.7 ± 4.3 minutes for mepivacaine, 10.0 ± 5.1 minutes for bupivacaine, and 11.3 ± 5.3 minutes for the combination group; P = 0.21 between all groups). The duration of motor block for the combination group (11.5 ± 4.7 hours) was between that of the bupivacaine (16.4 ± 9.4 hours) and mepivacaine (6.0 ± 4.2 hours) groups (P = 0.03 between bupivacaine and combination groups; P = 0.01 between mepivacaine and combination groups). Duration of analgesia was the shortest with mepivacaine (4.9 ± 2.4 hours), longest with bupivacaine (14.0 ± 6.2 hours), and intermediate with the combination group (10.3 ± 4.9 hours) (P < 0.001 for mepivacaine vs. combination group; P = 0.01 for bupivacaine vs. combination group). CONCLUSIONS: For ultrasound-guided interscalene block, a combination of mepivacaine 1.5% and bupivacaine 0.5% results in a block onset similar to either local anesthetic alone. The mean duration of blockade with a mepivacaine-bupivacaine mixture was significantly longer than block with mepivacaine 1.5% alone but significantly shorter than the block with bupivacaine 0.5% alone.

Reversible association of ribulose-1, 5-bisphosphate carboxylase/oxygenase activase with the thylakoid membrane depends upon the ATP level and pH in rice without heat stress.

Ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) activase (RCA) in the thylakoid membrane (TM) has been shown to play a role in protection and regulation of photosynthesis under moderate heat stress. However, the physiological significance of RCA bound to the TM (TM-RCA) without heat stress remains unknown. In this study, it is first shown, using experiments in vivo, that the TM-RCA varies in rice leaves at different development stages, under different environmental conditions, and in a rice mutant. Furthermore, it is shown that the amount of TM-RCA always increased when the Rubisco activation state and the pH gradient across the TM (DeltapH) decreased. It was then demonstrated in vitro that the RCA bound dynamically to TM and the amount of TM-RCA increased during Rubisco activation. A high level of ATP and a high pH value promoted the dissociation of RCA from the TM. Both the RCA association with and dissociation from the TM showed conformational changes related to the ATP level or pH as indicated by the changes in fluorescence intensity of 1-anilinonaphthalene-8-sulphonic acid (ANS) binding to RCA. These results suggest that the reversible association of RCA with the TM is ATP and pH (or DeltapH) dependent; it might be involved in the RCA activation of Rubisco, in addition to the previously discovered role in the protection and regulation of photosynthesis under heat stress.

Intraneural injection with low-current stimulation during popliteal sciatic nerve block.

BACKGROUND: Prevention of an intraneural injection of a local anesthetic during peripheral nerve blockade is considered important to avoid neurologic injury. However, the needle-nerve relationship during low-current electrical nerve localization is not well understood. METHODS: We postulated that intraneural needletip location is common during low-current stimulation popliteal sciatic nerve blockade. Twenty-four consecutive ASA class I-III patients scheduled for foot or ankle surgery under popliteal sciatic nerve block using a combined ultrasound and nerve stimulator-guided technique were prospectively studied. The end point for needle advancement was predetermined to be either an elicited motor response between 0.2 and 0.5 mA (100 mus/2 Hz) or an apparent intraneural location of the needletip as seen on ultrasound, whichever came first. The injection occurred at either end points provided the injection pressure was <20 psi. The injection was considered intraneural when injectate resulted in both the swelling and compartmentalization of the nerve within the epineurium. RESULTS: Elicited motor response could be obtained only upon entry of the needle into the intraneural space in 20 patients (83.3%). In the remaining four patients (16.7%), a motor response with a stimulating current of 1.5 mA could not be obtained even after the needle entry into the intraneural space. An injection in the intraneural space occurred in all patients who had motor-evoked response at current 0.2-0.4 mA. All 24 blocks resulted in adequate anesthesia for foot surgery. No patient developed postoperative neurologic dysfunction. CONCLUSION: The absence of motor response to nerve stimulation during popliteal sciatic nerve block does not exclude intraneural needle placement and may lead to additional unnecessary attempts at nerve localization. Additionally, low-current stimulation was associated with a high frequency of intraneural needle placement.

Lumbar plexus block using high-pressure injection leads to contralateral and epidural spread.

BACKGROUND: The main advantage of lumbar plexus block over neuraxial anesthesia is unilateral blockade; however, the relatively common occurrence of bilateral spread (up to 27%) makes this advantage unpredictable. The authors hypothesized that high injection pressures during lumbar plexus block carry a higher risk of bilateral or neuraxial anesthesia. METHODS: Eighty patients undergoing knee arthroscopy (age 18-65 yr; American Society of Anesthesiologists physical status I or II) during a standard, nerve stimulator-guided lumbar plexus block using 35 ml mepivacaine, 1.5%, were scheduled to be studied. Patients were randomly assigned to receive either a low-pressure (< 15 psi) or a high-pressure (> 20 psi) injection, as assessed by an inline injection pressure monitor (BSmart; Concert Medical LLC, Norwell, MA). The block success rate and the presence of bilateral sensory and/or motor blockade were assessed. RESULTS: An interim analysis was performed at n = 20 after an unexpectedly high number of patients had neuraxial spread, necessitating early termination of the study. Five of 10 patients (50%) in the high-pressure group had a neuraxial block with a dermatomal sensory level T10 or higher. In contrast, no patient in the low-pressure group (n = 10) had evidence of neuraxial spread. Moreover, 6 patients (60%) in the high-pressure group demonstrated bilateral sensory blockade in the femoral distribution, whereas no patient in the low-pressure group had evidence of a bilateral femoral block. CONCLUSIONS: Injection of local anesthetic with high injection pressure (> 20 psi) during lumbar plexus block commonly results in unwanted bilateral blockade and is associated with high risk of neuraxial blockade.

Ultrasound examination of peripheral nerves in the forearm.

BACKGROUND AND OBJECTIVES: We examined in a volunteer population whether nerves in the forearm could be seen consistently using ultrasound imaging and whether this new information could have implications for the way we perform regional anesthesia of the median, radial, and ulnar nerves. METHODS: Eleven volunteers underwent ultrasound examination of both forearms. The median, ulnar, and radial nerves were followed and images were obtained at the elbow, proximal forearm, mid forearm, distal forearm and wrist levels. In addition the radial nerve was followed proximally to a point 5 cm above the elbow. Images were compared for consistency of location of the nerves and depth from skin and width was calculated for each nerve at each level. RESULTS: Anatomy of each nerve was consistent except for one forearm where the median nerve was lateral to the brachial artery at the elbow and one forearm where a superficial ulnar artery only joined the ulnar nerve at the wrist. A convenient location for blockade of both median and ulnar nerves is the midforearm combining ease of visualization, ability to block all terminal branches and minimal potential for vascular injury. The radial nerve is seen most easily at the elbow although blockade of the superficial radial nerve may spare radial motor function. CONCLUSIONS: Nerves in the forearm are consistently located using ultrasound. Further confirmation in clinical practice is required.

Relationship between grain yield and leaf photosynthetic rate in super hybrid rice.

In order to explore the relationship between grain yield and photosynthesis, the yield composition and leaf photosynthetic rate in some super hybrid rices and ordinary hybrid rice 'Shanyou 63' as control were measured in 2000-2005. The results were as follows. (1) The yield levels of the four super hybrid rices, 'Pei'ai 64S/E32', 'P88S/0293', 'Jin23A/611' and 'GD-1S/RB207', were significantly higher, being 108%-120% of 'Shanyou 63'. (2) These super hybrid rices had a better plant type with more erect upper layer leaves and bigger panicles or more spikelets per panicle, being 125%-177% of spikelets Shanyou 63 spikelets. (3) Net photosynthetic rates of these super hybrid rices were significantly higher in the second leaf but not necessarily in the first leaf or flag leaf than those of spikelets Shanyou 63 spikelets. (4) The removal of half flag leaf led to a decline in the seed-setting rate, while the removal of half panicle induced its increase in spikelets GD-1S/RB207 spikelets. Hence, higher yield in these super hybrid rices can be attributed to their bigger panicles, better plant type and higher light use efficiency of their canopies. Raising the photosynthetic capacity of each leaf, especially flag leaf, is the key to overcome the photosynthate-source restriction on grain yield and to make a new breakthrough of yield potential in future breeding of super hybrid rice.